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Java Interactive Virtual Environment System - POLITesi

1. 135 LIST OF CODE SNIPPETS 7 3 B 1 C 1 D 1 The Network Test Sender Script o 135 JiveScript Shell Demo a a eke Se a a 159 JiveScript jME Demo 0 ile od AE AA 167 Rendezvous directory active page o o 177 List of Tables 7 1 Start up experiment results i 26 4a 44 444 44 444 7 2 Performance comparison 7 3 Qualitative performances assessment Abstract This paper presents the design and implementation of Java Interactive Vir tual Environment System JIVES a Java based Multi user Modular Networked Virtual Environment framework for web and desktop applications The whole architecture is subdivided into three main layers ordered as follows the Core implements the abstract features that are commonly required in the creation of Virtual Environments the Implementors layer consists in modules that can be contributed as building blocks in order to realize such features the application layer that defines its own scripting language that allows the programmer to es trange from lower levels implementation details The current state of development offers a Peer To Peer network and a 3D visualization module along with these we present a demonstrative application script An innovative HotSpot based Item Inventory Management System integrates a meaningful way to combine Inventory items and allows JIVES to differentiate from its predecessors Finally we propose a reflective evaluatio
2. psn steso _namel getclassi _scriptingl amp getidal _usest amp getinterface echo invokel echol So amp nativeTojaval eval eval evall e eval o evall eval DialogueNodel getRequests setRequestsl Y NETWORKADDRESS_BROADCAST NetworkAddress NetworkAddress e equalsi e getPeeridi getPeerNamel getRemoteActiveNodeaddress e isBroadcasti isLocaladdress getinstancel receiveMessagel sendMessagel amp RemotebialogueRequesti freezel getactions getanswerl getidl getParentid getProperties getQuestion getRendererl getsourceldi getTargetidi islssued etactions setanswer setissued setParentid getid getNamel getSceneldi setidl setNamel tSceneld setRendereri setSourcel setTarget unbindRequesti unfreezel o Y TYPE_REMOTE ACTION int Y TYPE_REMOTE_ACTIVE_NODE_EXIT int Y TYPE_REMOTE_ACTIVE_NODE_UPDATE int Y TYPE_REMOTE_ACTIVE_NODE_UPDATE REQUEST int TYPE_REMOTE_DIALOGUE int NetworkMessagel equals getPavloadi getSceneldl getSenderAddressi gettypel IsForcedLocalDispatch setForcedLocalDispatch setPayloadl setSceneldi setsenderAddress setTypel BagGraphi BagGraphNodel e bindcombinationt addcat
3. OpenGL OpenAL OpenCL The main goal of the LWJGL 55 project is to provide a technology which allows Java 51 programmers to get access to resources that are otherwise unavailable or poorly implemented on the current Java 51 platform The jMonkeyEngine 31 uses LWJGL as its rendering system 2 6 OpenGL The Open Graphics Library OpenGL 32 is a standard specification defining a cross language cross platform API for writing applications that produce 2D and 3D computer graphics The interface consists of over 250 different function calls which can be used to draw complex 3D scenes from simple primitives OpenGL is a low level procedural API requiring the programmer to specify the exact steps required to render a scene This contrasts with descriptive APIs such as Java3D 48 where a programmer only needs to describe a scene and can let the library manage the details of rendering it 2 7 Direct3D Direct3D 38 is part of Microsoft s DirectX application programming interface API Direct3D is available for only Microsoft Windows operating systems Win dows 95 and above and Open Source software Wine 11 It is used to render 3D graphics in performance based applications such as games Direct3D uses hardware acceleration if available on the graphics card allowing for hardware acceleration of the whole rendering pipeline 2 8 jMonkeyEngine jMonkeyEngine jME 31 is a high performance Java based 3D graphics library
4. Open inventory action Once the items have been selected they will appear in the bottom left corner of the window In the Shop window the desired trade must be selected using the Select button if the needed items correspond to the ones selected by the user the trade can be performed by clicking the Trade button A box informing the user that the trade has been successfully completed will appear At the contrary if something is not set in the way that the trade requires a box will appear communicating that the trade has been aborted 120 Development and Usage The ME 31 Implementor offers in the same way as the Shell Implementor the possibility to save or load a snapshot of current state of the running JIVES application The user has to open the JiveScript Console by typing the F1 key of the keyboard and then launch the saveState command in order to save the snapshot or the loadState command in order to load a snapshot previously saved The argument to be passed to the commands is the name of the snapshot and it must be included into double quotes The locations where the snapshot is saved are exactly the same ones already described in the Shell User s Manual a folder called Roaming jives states in the AppData directory if the running OS is a Windows system userHome jives states if the application is executed in MAC OS X Environment or under a Linux OS All the save files are stored in
5. e Module Class Advertisement describes a module class a low level JXTA 54 abstraction e ModuleSpecAdvertisement defines a module specification e ModuleImplAdvertisement defines an implementation of a given mod ule e Rendezvous Advertisement describes a Peer that acts as a Rendezvous Peer e Peer Info Advertisement describes the Peer Info resource The primary use of this advertisement is to hold specific information about the current state of the Peer such as uptime inbound and outbound message count 40 Design and Implementation JXSEImplementor has been designed to take into consideration only three of the JXTA 54 advertisements the Peer Advertisement the Rendezvous Adver tisement and the Pipe Advertisement The first two are used by JIVES to define Peer resources inside the network of a JIVES Virtual Environment application while the last one is needed to properly define the pipe communication channel used by the running application An example of the Pipe Advertisement used by the JIVES applications is shown in Code Snippet 5 2 Code Snippet 5 2 JIVES Pipe Advertisement lt aml version 1 0 encoding UIF 8 gt lt DOCTYPE jxta PipeAdvertisement gt lt jxta PipeAdvertisement xml space default xmlns jxta http jxta org gt lt Id gt urn jxta uuid 59616261646162614E504720503250334A69766573424173A96384656D6F04 lt Id gt lt Type gt JxtaPropagate lt Type gt lt Name gt JXTA
6. technetwork java javase documentation index html Oct 2011 ORACLE Java SE Downloads http www oracle com technetwork java javase downloads index html Oct 2011 ORACLE java com Java You http java com en Aug 2011 ORACLE javax script Java Platform SE 6 http download oracle com javase 6 docs api javax script package summary html Oct 2011 ORACLE Jogl Java net http java net projects jogl Aug 2011 ORACLE Jxta Java net http java net projects jxta Sept 2011 ORACLE lwjgl org Home of the Lightweight Java Game Library http lwjgl org Aug 2011 ORACLE NetBeans IDE http ww netbeans org Nov 2011 PINHO M S BOWMAN D A AND FREITAS C M Cooperative object manipulation in immersive virtual environments framework and techniques In Proceedings of the ACM symposium on Virtual reality software and tech nology New York NY USA 2002 VRST 02 ACM pp 171 178 QUAX P MONSIEURS P JEHAES T AND LAMOTTE W Using au tonomous avatars to simulate a large scale multi user networked virtual en vironment In Proceedings of the 2004 ACM SIGGRAPH international con ference on Virtual Reality continuum and its applications in industry New York NY USA 2004 VRCAI 04 ACM pp 88 94 ROXR SOFTWARE LTD Clicky Web Analytics in Real Time http www getclicky com Nov 2011 190 BIBLIOGRAPHY 60 RUSSELL G DONALDSON A F AND SHEPPARD P Tackling onl
7. 54 defines three types of pipes e Point To Point Pipes connect exactly two endpoints together an input pipe on one Peer receives messages sent from the output pipe of another Peer e Propagate Pipes connect one output pipe to multiple input pipes mes sages flow from the output pipe the propagation source into the input pipes e Secure Unicast Pipes is a Point To Point Pipe that provides a secure and reliable communication channel JXSEImplementor has been designed to use a single pipe communication chan nel for each JIVES Virtual Environment application the choice to support a fully Design and Implementation 39 broadcast communication has led to choose the Propagate Pipe as the JIVES communication channel in order to propagate a message sent by a Peer running a given application to all the Peers running the same application In JXTA 54 all the network resources such as Peers Peer Groups Pipes and Services are represented as advertisements Advertisements are language neutral meta data structures represented as XML documents The JXTA 54 protocols define eight different types of advertisements e Peer Advertisement describes the Peer s resources such as the name and the ID e Peer Group Advertisement describes Peer Group specific resources e Pipe Advertisement describes a pipe communication channel and it is used by the Pipe Service to create the associated input and output pipe endpoints
8. Development and Usage Launcher Page for JivesApplet Mozilla Firefox x Firefox Y Launcher Page for JivesApplet db 53 v file usr src jme JivesApplet dist Applet run applet html ME o ev Launcher Page for JivesApplet Figure 6 9 Executing the JivesApplet 86 Development and Usage 6 2 User s Manual The JIVES framework at the moment lets the developer create both textual and 3D Virtual Environment applications Two different User s Manuals are proposed the first one related to applications built using the Shell Implementor the second one related to applications built using the ME 31 Implementor Obviously according to the different Implementors that a developer can create for the JIVES framework totally different User s Manuals must be created The Shell User s Manual and the ME 31 User s Manual proposed in this section teach the user how to start and use applications built with the Implementors provided by default in the JIVES framework A third User s Manual is related to how start a JIVES application in a Web Environment In order to run a JIVES Virtual Environment application the user needs a Java Virtual Machine installed If the user does not have a Java Virtual Machine installed he just needs to visit the Java SE Downloads official page 50 and download the Java Runtime Environment JRE or the Java Development Kit JDK setup packages for his operating system and then install
9. Development and Usage 101 proceed with the exchange In case of trading with a PC the user specifies which items wants to trade and in which quantity and sends a request to the other user the latter has the possibility to accept or reject the trade and select one or more items to trade or even no one Once both the traders agreed on the exchange the trade is performed A trade between two PCs is shown in Figure 6 21 at the beginning both the traders have two coins at the end of the trade the second user has received the two coins of the first one coming to have four coins while the latter no longer has any item Jives java 80x24 JivesUser Coffer JivesUser2 ASA wae a eooo Jives2 java 80x24 e Trading the following items Trading the following items coin x2 No items to trade To receive To receive No items to receive coin x2 d Yes 0 Yes 1 No 1 No Do you wish to continue Do you wish to continue Q Trade complete Ready Ready Trade complete activate bag0 activate bag0 0 Open 0 Open 1 Activate item 1 Activate item 2 Combine items 2 Combine items 3 Cancel 3 Cancel Which action to perform Which action to perform 0 Performing action Open Performing action Open 0 CATEGORY_DEFAULT 0 CATEGORY_DEFAULT 1 found n 1 received Which category Which category 1 coin x4 Ready Figure 6 21 Trade between two Playing Characters By using the sa
10. Jives registerEventListener inventoryListener The items combinations in the JiveScript Shell Demo are defined as shown in Code Snippet 6 8 each item is characterized by an ID the category to which it belongs its HotSpots and its model For each HotSpot if a combination is defined the item that will be created as a result of a correct combination is reported In the model definition is specified the description of the given item description that 124 Development and Usage appears to the user when he selects the Examine action from the Item Inventory Screen Code Snippet 6 8 Shell Items combinations Define bago bagO makeBag 4 bag0 id woodenStick categories found combines new org jives implementors engine shell HotspotRenderer bottom null new org jives implementors engine shell HotspotRenderer tip stickWithWire l model new org jives implementors engine shell BagItemRenderer A strong and flexible wooden stick commonActionsRenderer gui id nylonWire categories found combines new org jives implementors engine shell HotspotRenderer edge stickWithWire new org jives implementors engine shell HotspotRenderer middle null l model new org jives implementors engine shell BagItemRenderer A piece of nylon wire commonActionsRenderer gui bagModel bagModel In the JiveScript
11. Performance Metrics and Evaluation 147 Internet Explorer Mozilla Firefox Google Chrome Apple Safari Opera O Other Figure 7 4 Web browser usage ments have shown a certain difficulty in using the Shell Test Demo but this was expected and can be easily explained since a textual Virtual Environment application is far less intuitive than the graphical counterpart This has been demonstrated with the experiment that gave the possibility to the users to use the ME 31 Test Demo of which they were fully satisfied With respect to de veloping with JIVES the experiments have proven that the framework is aimed at a medium expert user that has good knowledge in terms of Operating Sys tems and owns at least the basics of Java programming This can be considered a success due to the fact that the user does not need to be a real developer to cre ate a JIVES application However JIVES may still be seen as attractive also by expert users since they have the possibility to face new challenges when creating additional Implementors and custom actions that will extend the JIVES features In order to efficiently test the qualitative performances the users who took part in usability experiments were asked to answer a short questionnaire expressing their degree of satisfaction according to some qualitative indicators The degree of satisfaction has been measured in a range from unsatisfactory to very satisfac tory
12. entry on the project tree visible in the Projects tab then select Add JAR Folder and add the newly extracted dependen cies to the project as shown in Figure 6 4 4 The project is now configured to use the JIVES Library Writing a JiveScript application Even if any text processor can be used to write a JiveScript the below procedure can be followed in order to install the JiveScript plugin 15 the plugin will enable 78 Development and Usage myJivesProject File Modifica Visualizza Vai Segnalibri Aiuto y z usr sre jmp myJivesProject test jives jar MANIFEST MF master application jnip 7 oggetti 119 3 GB dispazio libero Figure 6 3 JIVES Project Folder using ME SDK Projects 0 x Files Services Asset Packe NS myJivesProject gt KE Project Assets D GA Source Packages gt r Libraries DO Cerca in 2 myJives Project Gi Reference as Add JAR Folder x 9 Relative Path Pathfrom Variable lt no sultable variable _ Nom fe Tipo file lasspath Entry folder ZIP or JAR file lv Figure 6 4 Adding JIVES Dependencies in ME SDK Development and Usage 79 content assist when editing JiveScript files and is available only for Netbeans 56 and jMonkeyEngine 31 SDK 1 Download Rhino 40 content assist Netbeans plugin from http plugins netbeans org plugin 39133 2 From the IDE Tools menu select Plugins On the Downlo
13. op _GET op LI if _GET op add _GET op remove match false if empty _GET addr prec match ELO ESO SISSI SAO ONES _GETL addr match if empty _GET addr2 4 if validate_ipv6 _GET addr2 validating ipv6 echo IPv6 valid n else echo IPv6 null n 178 Server side Rendezvous directory active page Y if empty _GET port preg_match 0 9 1 5 _GET port match if match empty _GET addr empty _GET port empty _GET program 4 not inserted also ipv6 addr2 due to the fact that some peers may not have a IPv6 address _GET op HW if _GET op query if empty _GET program 4 _GET op uE switch _GET op case list doc new DOMDocument doc gt load rendezvous xml rendezvous_list doc gt getElementsByTagName rendezvous foreach rendezvous_list as rendezvous nl program rendezvous gt getAttributeNode program gt value MD5 rendezvous gt getAttributeNode md5 gt value IPv4S rendezvous gt getElementsByTagName ipv4 IPv4 IPv4S gt item 0 gt nodeValue IPv6S rendezvous gt getElementsByTagName ipv6 IPv6 IPv6S gt item 0 gt nodeValue ports rendezvous gt getElementsByTagName port p
14. while running 1 Adding the Rendezvous Relay as a Discovery listener discovery addDiscoveryListener this Tools sleep 1000 Publishing the peer advertisement JXSETools publishPeerAdvertisement netPeerGroup discovery Tools sleep 1000 Retrieving remote Advertisements looking for peers JXSETools retrieveRemoteAdvertisements discovery this null Tools sleep 1000 if XMLConfigParser getLanChoice amp amp XMLConfigParser getInternetChoice 4 Updating time only when we have a Internet connection FileManager getInstance updateTime IPv4 IPv6 tcpPort RendezvousRelayManager getRendezvousID RendezvousRelayManager getScriptName RendezvousRelayManager getScriptMD5 y Clear the interrupted status Thread interrupted Thread sleep 27000 The JXTA 54 technology is a Peer To Peer technology based on the pub lishing of Advertisements Advertisements are language neutral meta structures represented as XML documents and are used to describe and publish the existence of a Peer s resources JIVES implements three types of Advertisements the Peer 64 Design and Implementation Advertisement the Rendezvous Advertisement and the Pipe Advertisement The Peer Advertisement is used to hold specific information about a normal Peer the Rendezvous Advertisement describes a Peer that acts as a Rendezvous Relay and the Pipe Advertisement describes the pipe communication channel use
15. Code Snippet 6 10 presents how the scene models and the elements inside the scene are defined For each element in the scene are bound predefined actions 126 Development and Usage that are the ones shown to the user when he activates it In Code Snippet 6 10 Scene 2 is set with the scene2PortalTo1 Artefact To that element is bound the PortalAction action that lets the user to move from Scene 2 to the previous one Code Snippet 6 10 Scene Model Definition Define scene models scene2Model new org jives implementors engine shell SceneRenderState new org jives sim SceneModelIntf destroy function activate function 1 echo n nSCENE 2 n This room has a quiet pond with crystal waters onActiveNodeAdd function jivesActiveNode if jivesActiveNode getModelType equals org jives network RemoteActiveNode org jives implementors engine shell SceneRenderState setupTradeAction jivesActiveNode bag0 org jives implementors engine shell SceneRenderState setupRemoteDialogue jivesActiveNode onActiveNodeRemove function jivesActiveNode scene2 new org jives core JivesScene Scene 2 scene2Model Ue oo 5S SS SS SS SSS SSS S555 Secre Y ZAP ooo cneiiee n scene2PortalTol new org jives core JivesActiveNode scene2PortalToi new org jives implementors engine shell ActiveNodeRenderer org jives implementors engine shell ActiveNode
16. DEST COMMIT engMessagelNetworkAddress NetworkMessage receiveMessage NetworkAddfess String a INIT COMMIT sendMessage NetworkAddress NetworkMessagq receiveMessage NetworkAddress String mergel EST COMMITTED gt INIT AND DEST mT merge receiveMessage Networkaddress String INIT COMMITTED gt INIT AND DEST COMMITTE iT rollbackThread stopl Figure 5 3 TradeltemsAction Commit this period of time both peers must reach the INIT_AND_DEST_COMMITTED state which is reachable if e The initiator committed and received the confirmation of the destination commit e The destination committed and received the confirmation of the initiator commit If a peer commits and doesn t receive the confirmation from the counterpart within the roll back thread time out it sends an abort message and it compensate its commit At that point when the counterpart receives the abort message it compensate its commit too even if it had already gone into INIT_AND_DEST_ COMMITTED state The protocol works using TCP IP so that the messages are always delivered and the only issue is the time that can intercur from packet send to packet receive which depends mainly on network load In case that due to the Design and Implementation 35 high network load the confirmation message is not received before the expiration of the roll back countdown the transaction is
17. The constructor Oparam senderAddress the NetworkAddress of the sender Oparam type the type of the message it can be TYPE_REMOTE_DIALOGUE TYPE_REMOTE_ACTIVE_NODE_UPDATE TYPE_REMOTE_ACTION Oparam sceneld the ID of the current scene Oparam payload the content payload of the message public NetworkMessage NetworkAddress senderAddress int type String sceneld String payload this senderAddress senderAddress this type type this sceneId sceneld this payload payload this forcedLocalDispatch false As shown in Code Snippet 5 7 the NetworkMessage object includes informa tions about the sender of the message the type of the request and the scene currently visited by the sender JIVES provides different types of requests the TYPE_REMOTE_DIALOGUE message allows a user to start a dialogue with an other Peer the TYPE REMOTE ACTIVE NODE UPDATE message speci fies that the given message is an update message sent by a Peer to all the Peers Design and Implementation 67 connected to the same network in order to communicate some changes in the properties of the sender Peer such as the position the colour the ID of the cur rently visited scene the TYPE REMOTE_ACTI N message is used to perform actions between the Peers connected to the same network In particular when using a TYPE_REMOTE_ACTION message the payload of the serialized object NetworkMessage includes the gi
18. e One Stop Shop The complexity of VE involves the operation of several different sub systems such as rendering networking database Although modularity may influence the design of each subsystem their operation re mains tightly coupled to each other Consequently the result is a monolithic architecture albeit modular Introduction 5 e Not Invented Here and Reinventing The Wheel These syn dromes imply the expenditure of resources on the re emergence of existing technology in building a Virtual Environment system Consequently ex ploring new approaches becomes quite limited e Poor Scalability Most Virtual Environment systems aimed at collabo ration claim to support in theory thousands of users when in reality all documented experiments in Collaborative Virtual Environments CVEs do not go beyond a few dozens With the online game community the number of user base is reported to be larger at the expense of significant large bud gets to increase the network and computational resources This approach is less than ideal since notoriously the Client Server architectures do not scale Only recently the development of Virtual Environment systems is considering these issues adopting different solutions such as modularity peer to peer archi tecture scripting languages code re usability Chapter 2 illustrates the main technologies adopted in the development of a Virtual Environment system while Chapter 3 present
19. 98 Development and Usage application around the world As shown in Figure 6 16 now in the scene there are two PCs one NPC and the Portal that lets switch from the current scene to the next one The user can move around the scene by using the move command as shown in Figure 6 17 and choose the destination of his movement e0 Jives java 80x21 e Ready move 0 Portal to Scene 1 1 Guy in the southwest corner 2 Cancel Where do you want to move 1 You are now near Guy in the southwest corner Ready activate scene NPC0 0 Talk 1 Trade 2 Cancel Which action to perform 0 Performing action Talk JivesUser gt gt scene NPC0 Hello scene0NPCO gt gt JivesUser Nice to meet you d Where am I 2 Who are you 2 Have a nice day Which question to ask Figure 6 17 Moving around the Scene and Interacting with a NPC The user can interact with the elements of the scene by using the activate command passing as argument the ID string or the local variable representing the entity he wants interact with names that the user can retrieve by launching the lookAround command In Figure 6 17 the user interacts with a NPC element and executes one of the actions provided by the developer of the application The JIVES Shell Demo is an Inventory based Virtual Environment and let the user collect and combine items The user has the possibility to perform all the opera tions related to the Inventory by u
20. A Junt E xml B Jav vaScript File B JSON File wy E OpenGL amp INLP File E Other a Properties File CO gt Ta Cascading Style Sheet Description Add Tacatar hnma adriann imanbauniatfarm accatnarbe iMF2 Acc Figure 6 6 Creating a new JiveScript 7 Select Empty JiveScript file from the Other category Proceed until the creation is finished When done the new file will be enabled to be edited using the JiveScript Editor as in Figure 6 7 restart and check that the plugin is active if this doesn t happen immediately 6 1 2 Building the JIVES project Build guide for Eclipse Indigo 1 From the File menu select New then Other 2 In the CVS category select Projects from CVS then click next Configure the connection as reported in Figure 6 8 and proceed 3 In the Select Module chose the Use specified module name option and fill it with jives 4 Press finish to import the CVS project into the workspace Development and Usage 81 E newJiveScriptTemplate jives X WJ f ee alse 98 aalo nm 1 org jives sim ActiveNodeModelIntfi a n 7 getProperties function setProperties fl 3 gt EF Interface implementation org jives sim ActiveNodeModellntf Completion proposal a getProperties function setProperties function hashMap getActivationEvent function jivesAction onPropertyUpdate function render fu
21. Design and Implementation 33 mi execute UivesEvent i sendMessage NetworkAddress NetworkMessage DA receiveMessage NekygpkAddress String de Select il items to trade a T J INIT ACCEPTED nextState e mergel receiveMessage NetworkAddfess String Accept t INIT AND DEST ACCEPTED nextState endMessage NetworkAddress NetworkMessage Setert Select items to thd nextState isendMessage NetworkAddress NetworkMessape dest e DEST SELECTED endMessage Networkaddress NetworkMessapg onfirm Confirm incoming and outgoing items sgndMessage Networkaddress NetworkMessage receiveMessage NetworkAddress String mergel Pea INIT CONFIRMED gt INIT AND DEST sii sgndMessage NetworkAddress NetworkMessage INIT AND DEST SELECTED nextState mergel Confirm receiveMessage NetworkAddfess String Confirm incoming and ou oihg items p DEST CONFIRMED nextState isendMessage NetworkAddress NetworkMessa pa INIT CONFIRMED mergel lt DEST CONFIRMED gt INIT AND DEST CONFIRMED e Swap items COMMIT rollbackThread start ndMessage NetworkAddress NetworkMessage receiveMessage NetworkAddfess String 34 Design and Implementation receiveMessage NetworkAddress String
22. Jives Advertisement lt Name gt lt Desc gt Pipe Advertisement of JivesBasicDemo network lt Desc gt lt jxta PipeAdvertisement gt The management of the network connection in the JIVES framework is totally transparent to the user the JXTA 54 network starts automatically when the JIVES Virtual Environment application has been executed and stops when the JIVES Virtual Environment application exits JIVES provides also the useful command reset used to restart the JXTA 54 network without exiting the application 5 1 5 JiveScript grammars SIMs and inline instantiation One of the design objectives was making JIVES entities interoperable both by the system fixed ways and by the application arbitrarily and it appeared clear Design and Implementation 41 that this issue had to be resolved using JiveScript It is necessary to allow the application to define specific behaviours and mount those into the management of the entities the system does this need arises as soon as there is an application specific request that the system has to cope with from rendering to producing the effects of an activation from building application logic to defining those same entities The idea behind the solution is achieved by inline instantiation of Java 51 interfaces using JavaScript as Code Snippet 5 3 shows Code Snippet 5 3 Inline Instantiation activable bindAction new org jives actions ActivateNodeWithltemActi
23. JivesObjectintf Enginelmpl mentorintf ace EE JivesActionModelintf Figure 5 8 JIVES Component Diagram The Component Diagram shown in Figure 5 8 depicts at a high level the struc ture of the framework 5 2 1 Universal Platform The JIVES Universal Platform includes the core classes and all the basic fune tionalities of the framework In particular the Universal Platform is composed by the JIVES Core which represents the kernel of the framework the Structured 54 Design and Implementation Interactivity Models SIMs needed to define specific behaviours for a Virtual En vironment the Persistence Layer responsible to load and save the game state of the application the Actions and Events Management System in charge to manage all the actions and events that can occur in the Virtual Environment application the Dialogues Manager which lets the developer instantiate dialogues between Playing Characters PC and between Playing Characters and Non Playing Char acters NPC the Bag Graph related to the management of the objects available in the Virtual Environment and their relations JIVES core The Core classes represent those identified to be basic entities of the environment namely Actions Active Nodes Bags inventories Bag Items Dialogues Scenes Events and Event Listeners All of those implement the JivesObjectIntf interface that exposes an unique identifier string A working copy of a JIVE
24. apple org jives core JivesBagltem catalog new org jives implementors engine jme ShopCatalog catalog addEntry tradeItem 1 dialogueItem 2 org jives implementors engine jme SceneRenderState setupTradeAction scene0NPCO bag0 catalog aa nta SUOI 2222 SS AD Trigger entrance action on scene 0 entranceAction new org jives actions PortalAction entrancePortal null scene0 entranceAction execute null Prevent further scripting __scripting false Appendix D Server side Rendezvous directory active page Code Snippet D 1 Rendezvous directory active page lt php define APPLICATION_DIRECTORY apps function validate_ipv6 value has to contain at least twice like in 1 or 1234 abcd if Gs ubstrSco unt valio return false only 1 double colon allowed if substr count value gt 1 return false groups explode value num_groups count groups 3 8 groups of 0 4 digits 1 group has to be at least 1 digit if num_groups gt 8 num_groups lt 3 return false empty_groups 0 foreach groups as group group trim group if empty group amp amp is_numeric group amp amp group 0 if preg_match a fA FO 9 0 4 group return false else empty_groups the unspecified address is not valid in this case return empty_groups lt num_groups true false if empty _GET
25. from handwritten codexes to webtalk II a 3D collaborative virtual environment system In Proceedings of the 2001 conference on Virtual reality archeology and cultural heritage New York NY USA 2001 VAST 01 ACM pp 61 66 BELFORE II L A KRISHNAN P V AND BAYDOGAN E Common scene definition framework for constructing virtual worlds In Proceedings of the 37th conference on Winter simulation 2005 WSC 05 Winter Simula tion Conference pp 1985 1992 BIUK AGHAI R P AND SIMOFF S J An integrative framework for knowledge extraction in collaborative virtual environments In Proceedings of the 2001 International ACM SIGGROUP Conference on Supporting Group Work New York NY USA 2001 GROUP 01 ACM pp 61 70 BLASCOVICH J Social influence within immersive virtual environments Springer Verlag New York Inc New York NY USA 2002 pp 127 145 BLIZZARD ENTERTAINMENT World of Warcraft http eu battle net wow en Sept 2011 184 BIBLIOGRAPHY 7 BossER A G Massively multi player games matching game design with technical design In Proceedings of the 2004 ACM SIGCHI International Conference on Advances in computer entertainment technology New York NY USA 2004 ACE 04 ACM pp 263 268 8 BUYUKKAYA E AND ABDALLAH M Efficient triangulation for P2P net worked virtual environments In Proceedings of the 7th ACM SIGCOMM Workshop on Network and System Support for Games New Yo
26. 47 Directives Beside of commands there are three important directives that compose the Jive Script syntax in version 0 2 they must be used to instruct the interpreter about the environmental conditions into which the script runs e _name sets a name for the current script There can be no unnamed scripts in fact when the interpreter starts or it is reset a new name for the current script is automatically generated but this directive is suitable to assign an human readable name Setting a name is important because it will be used to register in the Rendezvous directory both the Peer and the application that it is running 1 Parameter name the script name e _uses declares a dependency upon a certain Implementor or action or generally a Java 51 class or package There can be multiple calls to this directive one for each dependency that a script expects to find when it is run When a script is loaded the interpreter first checks that all the dependencies are satisfied and then proceeds to its execution 1 Parameter dependency the fully qualified name of a dependency e _ scripting sets the flag to allow disallow scripting from the moment it is parsed on Once is set to false only reset will enable scripting again As scripting we considered any of the following operations Instance or make any JIVES objects Execute multi line commands Execute variable assignments 1 Parameter scripting a bool
27. CONSORTIUM Basic External Authoring Interface http www web3d org x3d content examples ExternalAuthoringInterface index html Aug 2011 70 WEB3D CONSORTIUM Web3D Consortium VRML Archives http www web3d org x3d vrml Aug 2011 71 WEB3D CONSORTIUM X3D for Developers http www web3d org x3d Aug 2011 72 WHITE W Koch C GEHRKE J AND DEMERS A Better scripts better games Queue 6 November 2008 18 25 73 WIKIMEDIA FOUNDATION Wikimedia org http www wikimedia org Nov 2011 74 WORKFLOW T COALITION M AND NUMBER D Workflow Manage ment Coalition White Paper Events ReVision 1999 75 ZWITSERLOOT R AND SPILKER R Project Lombok http projectlombok org index html Oct 2011
28. DB4O 67 is written in Java and NET and provides the respective APIs It can run on any OS that supports Java 51 or NET It is of fered under multiple licenses including the GNU General Public License GPL the DB40 Opensource Compatibility License AOCL and a commercial license for use in proprietary software DB40 67 represents an object oriented database model One of its main goals is to provide an easy and native interface to persistence for object oriented programming languages Development with DB4O 67 database does not require a separate data model creation the application s class model defines the structure of the data in DB40 67 database DB4O 67 aims to avoid the object relational impedance mismatch by eliminating the relational layer from a software project A very interesting project 13 uses DB40 67 for universal storage primarily for SceneNode persistence and Ling queries 2 14 Ozone Ozone 19 is a fully featured object oriented database management system imple mented in Java 51 and distributed under the LGPL Open Source license The Technological background 13 Ozone 19 project aims to evolve a database system that allows developers to build pure object oriented systems Ozone 19 does not depend on any back end database to actually save objects It contains its own clustered storage and cache system to handle persistent Java 51 objects Ozone 19 includes a fully W3C compliant DOM impl
29. Each X represents a user s opinion As shown in Table 7 3 the obtained results show that the framework allows to create applications in particular 3D 148 Performance Metrics and Evaluation Virtual Environments that can be easily used by non expert users Moreover the development of a new Virtual Environment application through JiveScript is feasible even for users who are not real developers Table 7 3 Qualitative performances assessment Shell Demo ME Demo Applet Shell Demo ME Demo Applet Shell Demo ME Demo Applet Shell Demo ME Demo Applet Shell Demo ME Demo Applet Shell Demo ME Demo Applet Chapter 8 Conclusions and Future Work This chapter provides a broad overview of the work which was undertaken through out the project and discusses the limitations which were encountered during the project process The final section suggests the direction of future research and development which could be taken on the basis of this work 8 1 Conclusions The JIVES framework achieves almost all the goals set during the design phase extensibility ease of use and re usability Scalability can be considered achieved only partially but in a satisfactory manner due to the fact that there is a sub stantial room for improvement From a technical point of view JIVES can be significantly enhanced by integrating different optimizat
30. Jives loop in another thread new Thread Override public void run Jives getEngine loop Jives getNetwork stopNetwork System exit 0 y J Start At the moment of writing the procedure that automatically builds the applet is not completely working thus it must be integrated with the following BASH script Code Snippet 6 2 works on Mac OS X too 84 Development and Usage Code Snippet 6 2 Applet builder Bash Script bin bash dir usr src jmp JivesApplet cd dir dist Applet mkdir code mv code jar code cd code jar xf code jar rm META INF BCKEY SF META INF BCKEY DSA code jar cp R dir assets jar cf code jar cd jarsigner keystore jivesks dir dist Applet code jar adriano rm R dir dist Applet code The steps performed by the script are the following 1 Sets the project directory It must point to the location where the applet under development is present 2 Removes duplicates from the jar file beside removing an invalid signature and copying the assets directory 3 Repackages the jar 4 Signs the jar assuming that exists a jivesks file that represent a keystore to use for the sign and the user adriano in the above script is able to sign it 5 Removes the temporary extraction directory After a clean build and the execution of the script the JME test is working as an applet as shown in Figure 6 9
31. Ready activate bag0 Open Activate item Combine items 3 Cancel Which action to perform 2 Performing action Combine items 0 CATEGORY_DEFAULT 1 found 2 received Which category 1 0 hook x2 nylonWire x1 2 woodenStick x1 Which item 1 Selected nylonWire 0 CATEGORY_DEFAULT 1 found 2 received Which category 1 hook x2 1 nylonWire x1 2 woodenStick x1 Which item 2 Selected woodenStick 0 edge 1 middle Which hotspots from nylonWire 8 0 bottom 1 tip Which hotspots from woodenStick 1 Built new item stickWithWire Ready Il Figure 6 19 Ready lookAround The following are the elements of Scene 0 scene0PortalTo1l scene NPCO JivesUser JivesUser2 Ready activate JivesUser2 0 Trade 1 Talk 2 Cancel Which action to perform 1 Performing action Talk Hello User2 How are you JivesUser gt gt JivesUser2 Hello User2 How are you Ready JivesUser2 gt gt JivesUser I m fine Thx Combining Two Items through HotSpots Portal to Scene 1 Guy in the southwest corner Undefined position Undefined position ava 80x23 Pa cene 1 outhwest corner ives ivesUser2 How are you activate JivesUser 0 Trade 1 Talk 2 Cancel Which action to perform 1 Performing action Talk I m fine Thx JivesUser2 gt gt JivesUser I m fine Thx Figure 6 20 Free Chat between two Playing Characters
32. advertisement indexes and assist Peers with advertisement searches Also handles message broadcasting 36 Design and Implementation Proxy used by Minimal Edge Peers to get access to all the JXTA 54 network functionalities JXSEImplementor takes possession of this Peers subdivision with some modifi cations in the JXSEImplementor there are only two kinds of Peers the Full Edge Peers and the Rendezvous Relay Peers The JIVES Full Edge Peers can send and receive messages and cache advertisements They reply to discovery requests with information found in their cached advertisements but do not forward any dis covery request The JIVES Rendezvous Relay Peers are Super Peers that have been designed to have both the functionalities of the Rendezvous Peer and the Relay Peer in such a way that a NATed Peer has to connect to only one Super Peer the JIVES Rendezvous Relay Peer instead of two different Super Peers a Rendezvous and a Relay Peer in order to have a fully working Internet connec tion Each JIVES Peer that is either a simple Peer or a Rendezvous Relay Peer exposes a public address and a private address This distinction is needed only when using an IPv4 connection and it is not necessary when using an IPv6 con nection The public address represents the IPv4 address provided by the router used to manage the connection while the private address is the LAN address of the network managed by the router Firewall Fi
33. already developed in the Presentation Implementor Because of the over abundance of projects related to Virtual Environments Motivations and targets 25 design issues such as the scalability consistency and persistency requirements JIVES is not meant to be specialized in the optimization of any particular require ment although this kind of optimizations could be added in the future but differs for other reasons Unlike the existing Virtual Environments frameworks JIVES offers a fully integrated Item Inventory Management System through which the developer can manage all the items of the virtual scene specifying their imple mentation and behaviour Through JIVES it is possible to create a Virtual World in which users have their own inventory exchange items with each others or with Non Playing characters and use items to interact with the scene This fea ture allows JIVES to be particularly suitable for the creation of Inventory based games such adventure games or simulations but nothing prevents the developer from creating any other kind of Virtual Environment or 3D application by us ing our framework The additional feature offered by JIVES is the possibility to combine different items together in a smooth and interactive way through the JiveScript language the developer can define the relations between the Inven tory items allowing the creation of new items from existing ones The novelty introduced by JIVES is the possibili
34. appendChild text_IPv6 rendezvous gt appendChild IPv6 port doc gt createElement port text_port doc gt createTextNode _GET port port gt appendChild text_port rendezvous gt appendChild port PID doc gt createElement pid text_PID doc gt createTextNode _GET pid PID gt appendChild text_PID rendezvous gt appendChild PID time doc gt createElement time text_time doc gt createTextNode _GET time time gt appendChild text_time rendezvous gt appendChild time doc gt save rendezvous xml echo Adding completed else echo Adding failed Token not corresponding Jp break case remove if strcemp _GET token md5 _GET pid _GET program 0 doc new DOMDocument doc gt preserveWhiteSpace false doc gt load rendezvous xml doc gt formatOutput true root doc gt documentElement rendezvous_list root gt getElementsByTagName rendezvous nodesToDelete array foreach rendezvous_list as rendezvous program rendezvous gt getAttributeNode program gt value MD5 rendezvous gt getAttributeNode md5 gt value IPv4 rendezvous gt getElementsByTagName ipv4 gt item 0 gt textContent IPv6 rendezvous gt getElementsByTagName ipv6 gt item 0 gt textContent port rendezvous gt getElementsB
35. it is the turn to select the items to exchange in order to do that each user has to open his inventory and select one or more items or even no one When the items have been selected the user has to confirm Development and Usage 115 Monkey Engine 3 0 Frames per second 58 Figure 6 35 A successful combination eo Monkey Engine 3 0 JivesUser2is requesting to trade Do you wish to accept Yes No Frames per second 38 Figure 6 36 A Trade Request 116 Development and Usage eon Monkey Engine 3 0 JiwesUser accepted your trade request Ok Figure 6 37 The Notification that Trade Request has been accepted the offer by clicking the Confirm button as depicted in Figure 6 38 When both the users have confirmed the trade the items to be exchanged are visualized in the application screen the items that the user sends appear in the left bottom corner of the window while the ones that the user receives in the left top corner of the window If the users are still willing to conclude the trade it is sufficient that both click the Trade button located in the right bottom corner of the application window as represented in Figure 6 39 Finally trade is complete and a notification will appear to both users Fig ure 6 40 shows the notification of trade complete In the example shown in the screen shots it is clearly visible that the trade has been successfully accomplished the first use
36. jivesActiveNode activatel freezel getCurrentScene getid getModelTypel getProperty getRendererl renderi setCurrentScene setRendereri toStringl unfreezel amp JivesBagitemi activate bindCommonactions freezel getchildren getRendereri setRendereri toStringi unfreeze freezel getid e unfreeze jivestvent executeAction freezel getaction getidt getPolicyFlags isProci setactionl setPolicyFlagst setProcessed unfr handleEvent de 0 JivesEventListenerin ActiveNodeModelint BagModelintf JivesActionModellnt Transactionintf aborti getid getRollbackThread getStatel getTransactionModell IsAborted isCommitted mergel nextState setRollbackThread setTransactionModell getActivationEventi getPropertiesi onPropertyUpdate setProperties BagitemModelintf e activateltem 9 getactivationeventi retrieveltemi TransactionModelin O executel e getbescriptioni getactivationeventi getPropertiesi renderQuantitySelectioni setPropertiesi DialogueModelint O getkeyboardinputi Figure A 1 e renderanswer e renderQuestionsl changeState SceneModelintf activ
37. made especially for modern 3D development since it uses shader technology ex tensively jMonkeyEngine 31 is written purely in Java 51 and uses LWJGL 55 10 Technological background as its default renderer for OpenGL 32 access OpenGL 2 through OpenGL 4 is fully supported It provides a 3D scene graph based API with the latest state of the art features jME 31 is completely Open Source under the BSD license The last graphics engines of the Massively Multiplayer Game Research Frame work Mammoth 33 and the Open Wonderland framework 47 are based on the jMonkeyEngine 31 2 9 Nifty GUI Nifty GUI 43 is a Java 51 Library that supports the building of interactive user interfaces for games or similar applications It utilizes LWJGL 55 for OpenGL 32 rendering The base GUI layout is defined in XML and controlled dynam ically from the Java 51 code Nifty GUI helps the developer to layout stuff display it in a cool way and interact with it Nifty GUI 43 the de lessvoid nifty package is well integrated with jME3 31 through the com jme3 niftygui package 2 10 Client Server The Client Server Network architecture involves multiple clients connecting to a single central Server Usually the file server on a Client Server network is a high capacity high speed computer with a large hard disk capacity This kind of technology is implemented in most of the professional 3D games in particular the Massively Multi pl
38. might be fired forking the program execution all the JIVES entities involved in this concurrent situation must be kept consistent from one thread to another In the Java 51 language each thread is 50 Design and Implementation awarded his own stack but all the thread share the same heap In other words changes applied during runtime to the values of statical allocations will not be reflected from one thread to another while in the case of dynamic allocations they will The Java 51 keyword synchronized is used to avoid race conditions on a block of code meaning that only one thread will be executing that code from the beginning to the end even if the operating system put the currently running thread to sleep and activate another thread that is queued for that same code execution Many methods of the Jives class are synchronized generateld so that there will always be a locally unique ID loadState and saveState to avoid concurrent changes in the entities when they are persisted or restored The doLoop internal behaviour which consists of network updates and processing of events the latter case is especially important because event actions can actually concurrently exe cute other events It happens that those actions are executed in separate threads but want to manage entities reflecting changes of an action to another in this case the only way to achieve the right result is checking out a copy of those entities from the JIV
39. of successful message delivery JIVES has proved to be very efficient Due to the choice of the JXTA 54 Architecture as basis for the Networking Layer all the messages are sent adopting the TCP protocol which guarantees delivery of messages without duplication or data loss When it comes to ME 31 Test Demo network traffic gained a great benefit from the introduction of an optimization such as the linear interpolation the number of messages sent per second decreased by a 90 From the point of view of executing JIVES as a Java Applet the framework has pleasantly satisfied there are no substantial differences between the performance as a Java Applet and the local counterpart Moreover the possibility to deploy a JIVES application as a Java Applet gives a fast and easy way to ensure that even less experienced users are able to run the application Another important aspect is the fact that the applet works on most of the existing browsers so that everyone can access it In particular as shown in Figure 7 4 the fact that the JIVES Applet can be used with Internet Explorer Firefox Chrome and Safari allows the framework to be properly executed by 92 8 of web browser users The graph shows data updated to September 2011 extracted as median values from different sources such as Net Applications 42 Statcounter 63 W3Counter 1 Wikimedia 73 Clicky 59 The qualitative performances obtained by means of the performed experi
40. port gt item 0 gt textContent PID rendezvous gt getElementsByTagName pid gt item 0 gt textContent time rendezvous gt getElementsByTagName time gt item 0 gt textContent if IPv4 _GET addr amp amp IPv6 _GET addr2 amp amp port _GET port amp amp PID _GET pid amp amp program _GET program amp amp MD5 _GET md5 amp amp time null rendezvous gt removeChild rendezvous gt getElementsByTagName time gt item 0 newtime doc gt createElement time text_newtime doc gt createTextNode _GET time newtime gt appendChild text_newtime rendezvous gt appendChild newtime response Update process completed New time timetoprint _GET time echo response timetoprint doc gt save rendezvous xml else 182 Server side Rendezvous directory active page response Update process not completed Token not corresponding echo response break case gettoken token md5 _GET pid _GET program echo token break default gt lt hi gt Rendezvous directory lt hi gt lt php Bibliography 1 Awio WEB SERVICES LLC W3Counter Free Realtime Web Analytics is Laat 3 os http www w3counter com Nov 2011 BARBIERI T AND PAOLINI P Reconstructing Leonardo s ideal city
41. second one is related to the web page in which is executed the algo rithm to obtain the secret key needed by a Rendezvous to correctly encrypt and decrypt save states Both the URLS are by default set to web spaces hosted by SourceForge 24 but the developer of a JIVES application may host the Ren dezvous directory and the secret key algorithm using a server of his choice In this case the developer has to include the correct URLs inside the networkConfig uration default xml file or communicate them to all the users The JIVES Network Configuration Settings Graphical User Interface lets the user manage also a connection that works under a Proxy In this case the user has to select the Use proxy box and then specify the URL of the Proxy server in the ProxyHost field the Proxy port in the Port field the credentials in the Username and Password fields All the fields related to the Proxy connection are the ones Development and Usage 105 included in the Advanced network settings tab JIVES offers also an experimental feature the possibility to create an account for each user through which it is possible to save and load the application state related to the user s avatar The Network Settings Graphical User Interface gives the possibility to specify the credentials of the account by filling the Account and Password fields located just below the Username field Once the user has modified in the right way all the netwo
42. st RS ER ea ii I 5 1 1 Inventory Data Structure a resa Ge ae Ga 30 5 1 2 Event Driven Architecture 31 5 13 TradeltemsAction Protocol 32 5 1 4 Networking Layer Architecture 39 5 1 5 Jiveseript grammars ads ia a do 40 5 1 6 Critical conditions and their resolution 48 5 2 lt I pre mentatiOn i i a ati ot a ghd cea hala gare 53 5 2 1 Universal Platform 42s 4 lt 2 24 gi face we Pe bk 53 5 2 2 Networking Layer os sa 4 4 mad bw Dek Po ad fas 61 5 2 3 Middleware Layer iii ds ek 67 5 2 4 Application Layer pei REALI Pr 8s T2 6 Development and Usage 75 6 1 Developers Mammalia a ie oe Bare ie a ee sd 75 6 1 1 Development using JIVES 75 6 1 2 Building the JIVES project 80 6 2 A a ia A e ER be oe e i ae a E 86 6 2 1 Shell User s Manual op aaa 87 CONTENTS III 6 2 2 JME Users Manual spo Ad ds ee ES 102 6 2 3 Java Applet User s Manual 120 6 3 Sample JiveScripts te EEE 122 7 Performance Metrics and Evaluation 129 7 1 Performance Metrics ot a e ee ces ad 129 AN o A IIA Bom Sete Boars 142 8 Conclusions and Future Work 149 A A A A i Tae ga Boot Nan ahd 149 8 2 HRCA OKs poli bw BG te dt AA 150 Appendices 155 A JIVES Class Diagram 155 B JiveScript Shell Demo 159 C JiveScript ME Demo 167 D Server side Rendezvous directory active page 177 Bibliography 183 List of Figures 1 1 Reality Virtuality Co
43. sub folder jxse in which is located the networkConfiguration xml file In the case of a ME 31 based JIVES application there is no need to modify manually the network configuration file because JIVES provides an easy to use Graphical User Interface to manage the network configuration settings Once JIVES has been started the ME 31 Display Settings windows will appear The user can set the resolution the colour depth the Anti aliasing parameter and the Full screen option Once set and confirmed the Display Settings parameters a totally black screen appears by typing the Esc key a short menu is shown or hidden through which the user may decide to configure the network settings or quit the application By choosing the Network settings button the Network Settings Graphical User Interface is visualized as shown in Figure 6 22 The network settings are exactly the same already seen in the Shell User s Manual The user can choose the name of its avatar by filling the Username field start the JIVES application using a LAN connection or a Internet connection by selecting the proper checkbox In the case ofa LAN connection the user may start the JIVES application acting as a Rendezvous by checking the Host the session box or connecting to a Rendezvous running the same JIVES application in the Development and Usage 103 6800 jMonkey Engine 3 0 Basic network settings User name Local LAN connection e Internet co
44. the testShell Demo the network can be instantiated directly issuing the command Jives getNetwork startNetwork test org jives implementors network jxse utils Tools md5Converter test Then the receiver has to be started simply running the script reported in Code Snippet 7 1 134 Performance Metrics and Evaluation Code Snippet 7 1 The Network Test Receiver Script bin bash file 0 output txt log 0 log txt path usr src eclipse jives out Path of the testShell build function bot echo Jives getNetwork startNetwork test org jives implementors network jxse utils Tools md5Converter test while true do echo lookAround sleep 1 cat file while read line do found echo line grep gt gt peer0 if n found then recv_time echo date 4s N 1000000 sender echo line cut d f4 send_time echo line cut d 5 let DIFF recv_time send_time echo sender DIFF gt gt log fi done echo gt file Ponder next move sleep 0 5 done cd path touch file echo gt file touch log echo gt log bot java jar testShell jar tee file At last the file 0 log tzt will contain the delivery time of all the messages received and the respective provenance 0 output trt instead is used as storage to parse the output buffer iteratively The output files are prefixed with a serial ID so that di
45. the JIVES Virtual Environment application that the second user wants to join is running on a LAN connection the Local LAN connection button must be selected while the Host the session check box deselected and the JP Address and Port fields must be correctly filled with the IP address and the port of the Rendezvous user If the JIVES Virtual Environment application is running using a Internet con nection it is only necessary to select the Internet connection button JIVES itself automatically retrieves from the Rendezvous directory the informations related to the user who acts as a Rendezvous in order to let the second user to join the application In Figure 6 25 are shown the settings of a user who joins a JIVES application which works using a LAN connection Once the second user has joined the application immediately its avatar ap pears in the initial scene as shown in Figure 6 26 The user can interact both with Non Playing Characters and Playing Charac ters and with the Artefacts of the scene by simply clicking the right mouse button on the element with which the user wants to interact a list of available actions is shown Figure 6 27 represents an interaction with a Non Playing Character 108 Development and Usage eN jMonkey Engine 3 0 Basic network settings Local LAN connection e Internet connection O Rendezvous connection Hostthe session E Advanced network settings Net interface Use proxy E
46. the JiveScript ME 31 Demo at the beginning of the scripts make use of two important directives the directive __uses and the directive _name As shown in Code Snippet 6 6 the uses directives will be checked by the system to ensure that all the Implementors needed by the JiveScript application are available In the JiveScript Shell Demo as argument of the directive is passed the Shell Implementor while in the JiveScript jME 31 Demo is passed the ME 31 Implementor The name directive is used to define the name of the JIVES application Code Snippet 6 6 __uses and __name directives JIVESCRIPT_VERSION 0 2 reset __uses org jives implementors engine shell __name Jives Basic Demo echo De echo E cena ase aerate Rea SSS SSeS See Sa Sar Se SS SS SSS SE SSS SSS SaaS SSeS LOT echo Welcome to Jives Basic Demo echo Ves gt soso o sos 52912 So ess osos sesos UO echo This is a textual adventure engine that uses Jives Shell implementor and JiveScript echo Say help for a list of available commands Prevent further scripting __scripting false At the end of the script the __scripting directive is defined Usually when the script is in its final version this directive is set to false as in the JiveScript Demo In this case the script can be only loaded and not modified any more Setting the directive __scripting to true allows the JIVES developer
47. the Rendezvous directory possible by a Rendezvous Relay are related only to the Rendezvous Relay itself because it is not possible to modify the informations of an other Rendezvous without knowing its own Token In order to manage a sudden disconnection of a Rendezvous Relay the JIVES implementation provides that the server monitors continuously the existence of the Rendezvous registered on the Rendezvous directory In particular each Rendezvous Relay sends to the server once per minute an update message if the server does not receive any communication from a given Rendezvous Relay for more than a minute and a half the server considers disconnected the Rendezvous and unsubscribes it from Design and Implementation 63 the Rendezvous directory Any Rendezvous Relay while registering on the Rendezvous directory trans mits also the MD5 of the whole JIVES script currently running This is an additional layer of security which permits to be sure that only the peers running the same JIVES application with the same MD5 are interconnected in the net work related to the application itself When a user starts a JIVES application the Internet modality JIVES checks if the there are already Rendezvous running the same application if so the user is connected to the network as a normal peer if not JIVES automatically makes the user a Rendezvous Relay and registers it on the Rendezvous directory Code Snippet 5 6 Rendezvous Relay run method
48. the downloaded file The sample JIVES applications have been successfully tested by using the Java SE 6 Update 29 Development Kit See the Java 51 SE Documentation 49 for further informations about installing the JVM When JIVES has been executed it creates automatically a hidden folder called jives in the home directory of the user s OS In a MAC OS X or Linux Environment the folder is located in userHome while in a Windows system the folder is named Roamingljives and is created in CA Documents and Set tings user Application Data Roaming jives or CA Users user AppData Roaming jives depending on the Windows version the folder jives Roam ingl jives contains two sub folders one is called config the another one states The config directory contains a subfolder called jxse in which are placed the default JIVES network configuration file networkConfiguration default xml and Development and Usage 87 the customizable networkConfiguration cml network configuration file The lat ter file includes all the custom network settings of the user who is running the JIVES application The states directory will contain all the user save files The states folder is created only when there is at least one save file The folder disposal is shown in Figure 6 10 al fe oer ai a FAVORITES E All My Files Folders Fol ers Folders Downloads E config
49. the necessary tools in order to build a new JIVES application due to the lack of any knowledge in programming failed to create a new JIVES application Both users once they became familiar with the JIVES framework were satis fied with the experience 7 2 Evaluation This section critiques the software solution that has been developed during the course of this project evaluating the JIVES framework from a performance and functionality perspective This will aim to determine whether the developed solu tion matches the requirements which were outlined in the Design section 5 1 and whether JIVES is performant enough to become a viable solution for the Deploy ment of Networked Java based applications A reflective analysis on the entire project as a whole will also be taken discussing the validity of the approaches adopted the reasoning behind these approaches and an appraisal of the fulfilment of the aims and objectives which were outlined in chapter 4 Adopting the VESLOM 45 approach it has been possible to build a frame work that avoids a monolithic architecture JIVES has been developed according to the VESLOM 45 Layers obtaining in that way a good extensibility Neverthe less JIVES is not totally extensible and modular it allows the developer to define new Presentation and Network Implementors while maintaining unchanged the Core If the developer community will show interest in JIVES the framework will greatly improve by m
50. the right way all the operations already tested in the first exper iment Unlike the Shell Demo in this case the trading between PC has been considered much easier and intuitive moreover they encountered no problem at all in performing the HotSpots combination thanks to the usability of the auto Performance Metrics and Evaluation 141 matic alignment Obviously if due to Implementor design the HotSpots were implicit the time taken and the reasoning effort would have been higher Both users were also asked to perform the combination without the combination helper due to the lack of a reference system they encountered some problems in manag ing the rotation and translation of the items in the Combination Screen The time taken by the newbie user to obtain a successful combination was a bit longer with respect to the other user In both cases however the combination has been performed A third experiment has been performed in which the users were asked to run the ME 31 Test Demo as a Java Applet In this case the experiment showed that the execution of JIVES using a browser is definitely the faster and easier one especially from the point of view of the newbie user The only difficulty that has been encountered by the latter user was creating properly the java policy file in the right directory in order to let the applet access the user s machine Note that users had free choice about which browser use both execu
51. them they had to read carefully both the Manuals and try to perform the same operations described in the documents In particular they had to set up correctly all the necessary settings to run the De mos start the JIVES applications by loading the scripts and execute some actions inside the Virtual Environment such as moving around managing the Inventory combining items chatting and trading with a NPC and a PC saving and loading the application state The first experiment has been done by asking to execute JIVES and load the Shell Test Demo Both users have no problem to start JIVES by launching the java jar testShell jar command in a terminal although of course the time taken is definitely different the newbie user took a few minutes to understand how to launch the terminal the Command Prompt in his case move into the right directory and start JIVES Before loading the JiveScript Shell Demo they were asked to configure the network settings to run the application as a simple Peer who wants to connect to a Rendezvous already running the same application Both users have encountered difficulties in properly configuring the networkConfigura 140 Performance Metrics and Evaluation tion zml especially in understanding the meaning and usefulness of the various field of the XML file The newbie user has also committed some mistakes in modifying the document according to the XML rules since he has no knowledge about th
52. to intercept any event and decide which reaction to undertake even inhibiting the execution of the action bound to the intercepted event is an option It s important to notice that firing an event is not always the same thing as saying that the event happened because every fired event can be kept in a pool while they wait to be processed but only when the logic of an event isHappened method is satisfied the action bound to it is executed There are different types of events namely e Generic events the default ones those introduced by the program logic to perform its own tasks e Activation events occur every time an activable entity is activated by mean of an action e Remote receive events used by the system to synchronize the distributed state occurs when the local peer receives an update from the network Any event can be repeated many times because it will stay in the pool of fired events as long as it s needed depending on its retention policy The possible values of this policy are e Discard always The event is discarded as soon as it is retrieved from the pool independently of the fact that it has actually happened or it is likely to happen in the future This is useful when it s necessary to pre emptively 58 Design and Implementation fire an event and it is only possible to tell in a second moment if the action bound to that event must be executed e Discard when happened The event stays in t
53. user s computer This happens because the applet is signed with a digital certificate This certificate claims that the applet comes from the party named within and contains the digital signature of a certificate authority In order to correctly run the applet the user must accept the certificate request A An applet from simonesegalini altervista org is requesting access to your computer 4 I lai gt The digital signature from LWJGL has been verified _ Allow all applets from simonesegalini altervista org with this signature L Show Details L Deny o Allow Figure 6 43 The Certificate Request Because the JMEImplementor is quite memory consuming to run as a Java Applet the user might have to increase the Java 51 Heap of its Java 51 Virtual Machine at least augmenting it to 300 Mb This is possible by defining in the JVM Settings of the user s OS the parameter Xmx300m See http java sun com performance reference whitepapers tuning html section4 1 2 for further informations about increasing the Java Heap size The first time that the user runs the JivesApplet it takes a long time to start because the Java 51 Web Start has to download all the necessary packets from the server These packets are then stored in the Java 51 Web Start cache this permits to load the JivesApplet in 122 Development and Usage a much shorter time 6 3 Sample JiveScripts Both the JiveScript Shell Demo and
54. with two fields the first is a BagGraphHotspotIntf the second is an ID of another Bag item In the bag graph will be bound a combination between two nodes the object being defined and the one whose ID is specified in the combination using the given HotSpot as an arc Either of the combination fields can be null as seen in Code Snippet 5 4 If the ID field is null the arc is dangling while if the HotSpot field is null the combination Design and Implementation 45 happens without need to specify any HotSpot simply selecting the right parent items d model a BagItemModelInif that will be used as model when this item is activated or represented e common ActionsRenderer if this property is set a set of com mon actions will be automatically bound to this item The avail able actions will be i Select Deselect allows to extract a certain quantity of this item from the Bag ii Examine allows to display a description for this item Note that the value of this property must be a JivesRendererIntf 2 Parameter model a BagModelIntf that will be used as model when this inventory is activated or represented 3 Parameter combiner a BagItemCombinerModelIntf that will be used as model when the end user tries to combine items from this inventory e makeDialogue given a dialogue definition return a new JivesDialogue object 1 Parameter definition the definition of the dialogue in JSON is ag
55. 4 Technological background by about three times 2 17 Lombok Project Lombok 75 is a small Java 51 library that can be used to reduce the amount of Java 51 boilerplate code that is commonly written for Java 51 classes Project Lombok 75 does this code reduction via annotations that can be added to the Java 51 class replacing desired common methods It is possible to an notate any field with Getter and or Setter to let Lombok 75 generate the default accessors automatically or with Delegate in order to generate delegate methods that forward the call to the given field any class definition may be an notated with ToString to let Lombok 75 generate an implementation of the toString method or with EqualsAndHashCode in order to obtain the Lombok 75 implementations of the equals Object other and hashCode methods or with NoArgsConstructor to generate a constructor with no parameters Chapter 3 Related work Over the last decade research efforts in the Virtual Environment middleware industry were targeted at improvement of scalability persistence and responsive ness capabilities while much less attempts 44 have been aimed at addressing the flexibility maintainability and extensibility requirements in contemporary Virtual Environment platforms ATLAS 35 is a Distributed Virtual Environment DVE system that allows users on a network to interact with each other by sharing a common view of their states Th
56. A 54 is the possibility to create a virtual overlay network which allows a Peer to interact with other Peers even when some of them are behind NATs and firewalls or use different network transports As explained in 68 the JXTA 54 Architecture is made of three logical layers e Platform Layer it is the base of JXTA 54 and contains the implementa tion of the minimal and essential functionalities required to perform Peer To Peer networking This layer is also know as the core layer e Services Layer it contains additional services that are not absolutely necessary for a Peer To Peer system to operate but which might be use ful searching and indexing storage systems file sharing distributed file systems resource aggregation and renting protocol translation authentica tion PKI Public Key Infrastructure 12 Technological background e Applications Layer it includes implementation of integrated applications Peer To Peer instant messaging document and resource sharing content management and delivery Peer To Peer email systems distributed auction systems In order to know the advantages and the disadvantages of the JXTA 54 technology it is interesting to read the performance study written by Halepovic and Deters 27 2 13 DB40 DB40 DataBase FOR Objects 67 is an embeddable Open Source object database for Java 51 and NET developers It is developed commercially licensed and supported by Versant
57. ANTAO J PINTO A AND WAZLAWICK R S Development of a collaborative virtual environ ment for educational applications In Proceedings of the sixth international conference on 8D Web technology New York NY USA 2001 Web3D 01 ACM pp 61 68 LEE D Lim M HAN S AND LEE K ATLAS A Scalable Network Framework for Distributed Virtual Environments Presence Teleoper Vir tual Environ 16 April 2007 125 156 MENCHACA R BALLADARES L QUINTERO R AND CARRETO C Software engineering HCI techniques and Java technologies joined to develop web based 3D collaborative virtual environments In Proceedings of the 2005 Latin American conference on Human computer interaction New York NY USA 2005 CLIHC 05 ACM pp 40 51 MICHELSON B M Event Driven Architecture Overview Originally Pub lished February 2 2006 Feb 2011 MICROSOFT CORPORATION Introduction to Direct3D 10 SIG GRAPH 2007 http www microsoft com download en details aspx displaylang en amp id 2858 Aug 2011 MORGAN G Lu F AND STOREY K Interest management middleware for networked games In Proceedings of the 2005 symposium on Interactive 3D graphics and games New York NY USA 2005 13D 05 ACM pp 57 64 188 BIBLIOGRAPHY 40 MoziLLa Rhino Javascript for Java http www mozilla org rhino Aug 2011 41 MYTHIC ENTERTAINMENT Ultima Online http www uoherald com Sept 2011 42 NETAPPLICATIONS C
58. ES registry and then check back in when the appropriate changes have been performed This is why often code does not refer to this when accessing even the protected fields of a class but uses the registry instead or an instance of the same class passed in as a parameter like it happens in TransactionIntf nertState method jME HotSpot Combinations helper A combination that involves HotSpots can be very straightforward to think be cause the user can visually identify the possible candidates However it can be extremely difficult to realize a 2D representation of a 3D space doesn t give the perception of depth and this is a major issue when it comes to aligning precisely two points in space To help the user in this situation the Implementor pro vides an automation that takes care of the orientation and position of the chosen Design and Implementation 51 HotSpots so that once they have been selected by a mouse click they become immediately aligned and at that point it s sufficient to get the two items close enough to perform the combination by means of the middle mouse button or the space bar The algorithm cannot perform the alignment in terms of a pure rotation because there are too many degrees of freedom to affirm if the rotation involves one two or perhaps all of the three axes Consequently the best approach involves one rotation and one translation arctan a X Figure 5 6 Rotation step of the
59. Frames per second 36 Figure 6 25 JIVES Peer jME Network Configuration Settings 8900 jMonkey Engine 3 0 JivesUser2 JivesUser Vertic Frames per second 49 Figure 6 26 A second user joins the Scene Development and Usage 109 eon iMonkey Engine 3 0 Figure 6 27 Interacting with a NPC By selecting the Talk action when interacting with a NPC it is possible to access to the predefined dialogue related to the given NPC A dialogue with a NPC is proposed in Figure 6 28 It is also possible to chat with Playing Characters by activating the PC with the right mouse button and selecting the Chat action from the actions list proposed to the user A chat between two Playing Characters is shown in Figure 6 29 The user can also chat with an other Playing Character by following a different procedure he has to activate his avatar by right clicking on it and selecting the Chat action In the chat window an Invite button permits to the user to invite one or more Playing Characters currently present in the same scene The invite menu is proposed in Figure 6 30 The user can interact also with the so called Artefacts the fixed elements of the scene In the JiveScript ME 31 Demo the starting scene has only one Artefact a portal that lets the user move from the current scene to the next one The portal has to be activated by right clicking the mouse and then select the Enter action Imm
60. GB 800 MHz DDR2 SDRAM and Graphics Card Nvidia Geforce 9300M 256 MB For each hardware the experiment is done on idle processor and averages taken over ten independent runs In order to test the performance of the network all the experiments have been reproduced by using a Wireless Local Area Network WLAN 802 11n 450 Mb s and an Internet ADSL connection with a 8128 kbps downstream connection speed and a 480 kbps upstream connection speed At start up a measure is done on the period of time it takes to initialize JIVES and start the ME 31 Test Demo in window mode with a 800x600 pixels 130 Performance Metrics and Evaluation resolution 24 bpp colour depth and anti aliasing filter disabled Table 7 1 Start up experiment results 18 92 T 2088 76 10 1720 107 51 15 05 EN nN w 00 In Table 7 1 are shown the results obtained from the start up experiment Us ing the MacBookPro the start up takes an average of 17 14 seconds to load JIVES and start the Demo ranging from a minimum of 16 4 seconds and a maximum of 19 3 seconds the iMac obtains an average of 20 78 seconds with a minimum of 20 3 seconds and a maximum of 21 6 seconds the MacBook performs the start up in an average of 25 54 seconds obtained from a range between 23 9 and 28 0 sec onds on the Sony Vaio the experiment reveals a minimum of 22 1 seconds and a maximum of 23 1 seconds reaching an average of 22 62 seconds As a result of this exper
61. Metrics and Evaluation 145 Peers execute the same application a huge number of messages are sent through the network In particular the main network performance problem resides in avatar movements and state updates that produce an high number of message exchanges Even when an avatar doesn t move for simplicity it sends an update message to the other users connected in the same scene Nevertheless experimental simulations showed up that the system scales up smoothly with ten users in a shared session This result does not fit well within expectations the goal was to be able to support at least 100 peers simultaneously This is not to be regarded as a failure by adopting the right network traffic reduction algorithms such as dead reckoning 9 the network scalability can significantly improve At the moment due to the lag observed in the performed experiments JIVES can not be considered capable of supporting the so called real time applications such as First Person Shooters with a lag that has to be below 150 ms By adopting network optimizations techniques it will be possible to reduce the network lag in order to extend the support also to this kind of applications But this is the only limitation from Inventory based games to training simulations such as simulations aimed to train the user in critical situations to collaborative E Learning Virtual Environments such as interactive 3D class rooms or professional working environmen
62. Model gui Bind dialogues to NPC sceneONPCO new org jives core JivesActiveNode scene0NPC0 new org jives implementors engine shell ActiveNodeRenderer org jives implementors engine shell ActiveNodeRenderer TYPE_NPC Guy in the southwest corner scene0 addActiveNode scene0NPCO scene0NPCO bindAction new org jives actions StartDialogueAction scene0NPCODialogue0RootAction scene0NPCODialogue0Root getId Bind trade to NPC tradeltem Jives get apple org jives core JivesBagltem catalog new org jives implementors engine shell ShopCatalog catalog addEntry tradeItem 1 dialogueItem 2 org jives implementors engine shell SceneRenderState setupTradeAction sceneONPCO bag0 catalog fatato Stami eRe e Z Trigger entrance action on scene 0 entranceAction new org jives actions PortalAction entrancePortal null scene0 entranceAction execute null Prevent further scripting __scripting false Appendix C JiveScript ME Demo Code Snippet C 1 JiveScript ME Demo JIVESCRIPT_VERSION 0 2 reset __uses org jives implementors engine jme __name Jives Basic Demo ao A Sepe o tet oh gui org jives implementors engine jme GUIState getInstance bagModel new org jives implementors engine jme BagRenderState bag0 bagCombiner new org jives implementors engine jme BagCombinerState Set the model to use for the playing characters org j
63. OM Net Applications Bringing Together Applica tions Services and Partners http www netapplications com Nov 2011 43 ss NirtY GUI Nifty GUI a Nifty GUI for your Java OpenGL LWJGL ap plication http nifty gui lessvoid com Oct 2011 44 OKANDA P AND BLAIR G OpenPING a reflective middleware for the construction of adaptive networked game applications In Proceedings of 3rd ACM SIGCOMM workshop on Network and system support for games New York NY USA 2004 NetGames 04 ACM pp 111 115 45 OLIVEIRA M Virtual environment system layered object model In Pro ceedings of the 2004 ACM SIGCHI International Conference on Advances in computer entertainment technology New York NY USA 2004 ACE 04 ACM pp 194 202 46 OLIVEIRA M CROWCROFT J AND SLATER M An innovative design approach to build virtual environment systems In Proceedings of the work shop on Virtual environments 2003 New York NY USA 2003 EGVE 03 ACM pp 143 151 47 OPENWONDERLAND FOUNDATION Open source 3D virtual collaboration toolkit Open Wonderland http openwonderland org Aug 2011 48 ORACLE Java SE Desktop Technologies Java 3D API http www oracle com technetwork java javase tech index jsp 138252 html Aug 2011 BIBLIOGRAPHY 189 49 50 51 52 193 5 4 55 56 57 58 59 ORACLE Java SE Documentation at a Glance http www oracle com
64. POLITECNICO DI MILANO V Facolta di Ingegneria Master of Science in Computer Engineering Dipartimento di Elettronica e Informazione Java Interactive Virtual Environment System JIVES a Java based Multi user Modular Networked Virtual Environment framework Relatore Prof Thimoty BARBIERI Tesi di Laurea di Adriano DALPANE Matr 736581 Simone SEGALINI Matr 739362 Anno Accademico 2010 2011 The computer programmer is a creator of universes for which he alone is responsible Universes of virtually unlimited complexity can be created in the form of computer programs Joseph Weizenbaum Contents 1 List Ob Figures ol it td E ale A hos V List ofCGodeSmiippelo a sies ae pala e ae at IX Lishot Tables 2 0 32 we OPE a di Ab alain XI Abstract XIII Estratto XV Introduction 1 1 1 Development of a Virtual Environment system 3 Technological background 2 VRME Li AH ea a pieno die ae diet N IS cy O GI E O O O 00 00 00 Nn N 2 8 jMonkeyEngine ia sali i slides tibia ei 20 NINY GUL he oa il aaa eg 10 2 10 Chent Scivef suo gina Aaa rl a 10 Pese To Lech ci sita da en ent i 11 A E sane e Ein ein VE te O 11 II CONTENTS DIAC Se A ia a ue nds are tie A S 12 Du O Cx eee es rice dirti ee A Pee BI Pee Bs Pa 12 DIO CFF Sii le ieri ii 13 2 10 Java a DI ARA il LA ALLA ai 13 A sc leali phi ht nd et ie e fia 14 3 Related work 15 4 Motivations and targets 23 5 Design and Implementation 27 oil Desi eit
65. Renderer TYPE_PORTAL Portal to Scene 1 scene2 addActiveNode scene2PortalTo1 scene2PortalToi bindAction new org jives actions PortalAction scene2PortalTolAction scene2 scenel In the initial scene of the JiveScript Demo there is also a Non Playing Char acter defined with a preset dialogue The whole dialogue is reported before the definition of the NPC and then bound to it by using the StartDialogue Action ac tion The dialogue requests are structured into three main parts the question the answer and the actions related to that answer In Code Snippet 6 11 a part of the dialogue related to the NPC of the first scene is presented Development and Usage 127 Code Snippet 6 11 A predefined Dialogue AND leer Dialogue 0 sceneONPCODialogueORoot makeDialogue 4 sceneONPCODialogueORoot question Hello answer Nice to meet you actions new org jives actions StartDialogueAction scene0NPCODialogue0RootReq0Action scene0NPCODialogue0Intro dialogueModel gui makeDialogue 4 sceneONPCODialogueOIntro question Where am I answer You are in Jives basic demo actions new org jives actions StartDialogueAction Jives generateld scene0NPCODialogue0Dialogues question Who are you answer I m a non playing character I m here to demonstrate the dialogue system Ask your questions actions new org jives actions Sta
66. S object can be checked in or out from the JIVES registry using its identifier The purpose of using the registry is that of creating logical references instead of pointers to memory which would incur in cyclic references and the ability to retrieve an object that is needed at any time anywhere in the code without having to propagate widespread and intricate references Furthermore being JIVES by nature a distributed system it arises the need to store user data from the volatile memory into a persistent secure location for each and every peer This way it is possible to restore a consistent state later on Accordingly the objects in the JIVES registry represent the state of the application The security is a crucial aspect to bare in mind due to the fact that external modifications of the persistent location would lead to an incoherent situation or perhaps would advantage one part at the expenses of the others Of course a server side double check of the user data integrity can be introduced on top of the minimal but efficient mechanism that the universal platform guarantees which consist in an encrypted local object database Design and Implementation 55 All of the JIVES object share a common pattern an internal management that the system deals with to put the rails on the object behaviour and the exter nal implementation which resolves to the methods the implementor defines or the programmer code injected by scripting This dual na
67. a JIVES di differenziarsi dai sis temi finora sviluppati Infine proponiamo una valutazione dell intero progetto e discutiamo le possibili direzioni di sviluppo futuro JIVES punta ad essere una soluzione di trade off ad un problema complesso completamente Open Source estensibile flessibile riutilizzabile e caratterizzato da un design sperimentale pu essere considerato un buon risultato di ricerca nel panorama dei Virtual Environ ment frameworks Chapter 1 Introduction An exact definition of a Virtual Environment VE is difficult to find A common definition denotes a Virtual Environment as a computer based simulated environ ment intended for its users to inhabit and interact via avatars This habitation usually is represented in the form of two or three dimensional graphical repre sentations of humanoids or other graphical or text based avatars Blaskovich 5 defines a Virtual Environment as synthetic sensory information that leads to perceptions of environments and their contents as if they were not synthetic po Mixed Reality MR 7 i_r _ Real Augmented Augmented Virtual Environment Reality AR Virtuality AV Environment Figure 1 1 Reality Virtuality Continuum According to the definition of the Reality Virtuality continuum shown in Fig ure 1 1 in which the range scales between the completely virtual a Virtuality and the completely real a Reality Virtual Environments lie on the right side of the
68. ack countdown reaches zero so the transaction is aborted Persistence of complex classes All JIVES core classes are heavily dependent on the other parts of the framework even more important not all their fields are serializable thus it s simply not possible to store them as data being that an XML representation a serialization or a database entry To overcome this limitations JivesObjectIntf exposes a freeze method to save the entity and an unfreeze method to restore it What happens in this methods is that an apposite storage implementing PersistenceIntf is used to store on freeze then restore on unfreeze the state critical fields of the entity instead of storing the whole entity This approach allows to use the setProperties method of JivesRenderableIntf to produce right results in even more specific cases For example let s consider the case that self active node is restored that one is actually a RemoteActiveNode that has a network address The persisted network address though is no longer consistent and only a fine grained filter allows the old state to be appropriately merged with the new state Concurrency and thread safety issues A JIVES application cannot be restricted to a single thread design It s indeed convenient that Implementors rely on their type specific threads like the render thread in a Presentation Implementor or the network messages dispatcher in a Network Implementor but also JIVES events
69. ad the binaries of the JIVES library and of the test Implementors The Javadoc of the project is accessible from http jives sourceforge net javadoc jives The guide will propose a step by step procedure to follow in order to develop with JIVES both using Eclipse 64 and MonkeyEngine 31 SDK which is built upon the Netbeans 56 Platform There are different areas of development here briefly explained e Applications the most common developer will need to setup the project with the JIVES library the right Implementors then just focus on writing 76 Development and Usage the application using JiveScript e Implementors and extensions a developer can also configure the project only using the JIVES library and write by himself the Implementors needed and maybe even customized actions that are not available by default This code might also be exported with a built target and made available to other projects e Contributing to the Core new features and bug fixes can be contributed to the Core by either committing directly to the JIVES CVS or submitting a patch For this kind of development read further in 6 1 2 Next this guide will show how to setup the development application using JIVES library If you wish to use one of the test Implementors beside the library repeat exactly the same steps shown below using the Implementor binaries instead Setup guide for Eclipse Indigo 1 From the File menu select New then Ja
70. aded tab click the Add Plugins button 3 Select the downloaded file It will be added to the list of downloaded plugins as reported in Figure 6 5 When ready press the Install button follow the installation instructions and restart the IDE Y Tools Window Help Plugins x Y z r Updates Available Plugins 26 Downloaded 1 Installed 41 Settings Add Plugins Search Instau_JName _________ b z wa F pt Rhino co s Javascript Rhino content assist Remove en Community Contributed Plugin sd Version 0 1 2 Author Adriano Dalpane Date 15 06 11 Source 1308 137940_org netbeans modules jsrhinocontext TD Install 1 plugin selected Figure 6 5 Installing JavaScript Rhino Content Assist 4 Download the JiveScript editor Netbeans plugin 15 5 Install the JiveScript editor Netbeans plugin 15 following the same pro cedure shown at steps 1 2 3 for the Rhino content assist Netbeans plugin installation 6 From the Projects tab right click on the previously configured project name 80 Development and Usage myJivesProject in this example then select New Other The window depicted in Figure 6 6 will appear New File x Steps Choose File Type 1 Choose File Type Project myJives Project Zi se Categories File ET E Material e 5 EXE Empty JiveScript file Scene HTMLFite i aya E XHTMLFite JavaBeans Obje
71. ain a single property with value where the property is the ID of the dia logue and its value a collection of dialogue requests 46 Design and Implementation Code Snippet 5 5 Dialogue definition dialogueId id URLA className question answer actions Actions examples myActionObject new org jives actions JivesActionIntf do Each dialogue request is defined in JSON too Advantage of this design is the possibility of reusing objects in the definitions or even instancing entities inline as it can be seen in the actions definition of Code Snippet 5 5 The properties defined in each dialogue request are a id Optional The ID of the dialogue request useful to refer to it will be generated if omitted b className Optional class name of the request instance one of DialogueRequestIntf Defaults to org jives dialogues DialogueRequest c question a string for the dialogue initiator to present as question d answer a string to receive as corresponding answer e actions performed when the request being defined is issued If the dialogue should go on it must explicitly define a StartDialogue Action here Parameter model a DialogueModelInif that will be used as model when this dialogue is activated Parameter renderer a JivesRendererIntf that will be used for the dialogue request representation Design and Implementation
72. al to Scene 1 DE scene2 addActiveNode scene2PortalTo1 scene2PortalTo1 bindAction new org jives actions PortalAction scene2PortalTolAction scene2 scenel DE a ro ron rr rirrorrccrrDrrcorDio crono icona scene2Pond new org jives core JivesActiveNode scene2Pond new org jives implementors engine shell ActiveNodeRenderer org jives implementors engine shell ActiveNodeRenderer TYPE_NPC nA pond scene2 addActiveNode scene2Pond scene2Pond bindAction new org jives actions ActivateNodeWithItemAction useFishingRodAction bag0 scene2Pond new org jives sim JivesActionModelIntf 1 execute function jivesEvent action jivesEvent getAction if action getBag getSelectedItens size 1 gui notification Select exactly one item from bag to ap Ocean else selectedItem action getBag getSelectedItems get 0 getId if selectedItem equals fishingRod gui notification Fishing else gui notification selectedItem doesn t work here yp getDescription function return Fish render function jivesRenderableIntf gui notification this getDescription RO DS OQ sas Ses SSsS 33S 56555 6 5 SS 5 59S SS SS SS SS SS SSS SS SSS SSS sceneiPortalToO new org jives core JivesActiveNode sceneiPortalTo0 new org jives implementors engine shell ActiveNodeRenderer org jives implementors engine shell ActiveNodeRenderer TYPE_PORTAL Portal to Scene 0 DE
73. an only work with their respective implementor this means the same script should be ported to differ ent implementors because it simply won t work with all possible implementors out of the box However to demonstrate the validity of the generic and versatile 68 Design and Implementation design over the rigid full portable statical presentation structure two very differ ent implementors are proposed and discussed further on and the same JiveScript application was ported to both of them Shell Implementor This implementation is a MUD Object Oriented MOOs that resembles those of early eighties adventure computer games in which the player would read descrip tions of the situation his avatar was into and would react by typing commands in a shell to move around interact operate the virtual environment and the inventory and so on A list of instructions can be stored as a program and then executed The command line interface is equipped with code completion and suggestions to ease the rapid writing Although a complete list of commands is available entering the help command three main commands allow the end user to interact with the virtual environment this is a huge simplification of all the underlying complexity Those commands are e lookAround returns the list of surrounding entities e activate perform activation of the activable whose id is passed as param eter e move allows the avatar to move around in t
74. anism of account authenti cation secret key retrieval and snapshot encoding can be completed This is the first step to allow the exploitation of JIVES in commercial applica tion because until now the unencrypted save state is open to fraudulent modifications that will corrupt the distributed application state e Cheat engine protection although not easy to exploit the software is as any resident application exposed to direct and fraudulent RAM access in order to try to modify in game variables values Even if a correct syn chronization with the persistence layer would greatly reduce this flaw it might be reasonable to think about a possible server side checkpoint system to memorize and confront the client coherence states e Network traffic reduction this is actually an Implementor issue due to the fact that JXSElmplementor largely resorts to the use of broadcasting and due to the frequent update messages that the JMEImplementor needs in order to synchronize state and position of the peers Actually the test Conclusions and Future Work 151 implementors were not studied deeply for performance optimization as this is absolutely in scope of a commercial application but not a must have for our framework test A linear interpolation of the Playing Character s movements has already been implemented allowing to reach a significant reduction in terms of network traffic rate the number of messages per second sent by each Peer has
75. ased network lag depending on the Internet connection speed Using an ADSL with a 8128 kbps downstream connection speed and a 480 kbps upstream connection speed the lag increased to a maximum of 3 seconds In this specific case the distance that the signal had to run through was about 30 km In order to test the JXSE network on higher traffic loads it has been neces sary to simulate it due to the impossibility to provide an adequate number of hardware machines This kind of testing has been achieved through the Shel lImplementor A BASH 21 script has been used to automatically interact with a running instance actually performing like a bot Through this setup we were able to perform the network performance analysis The objective of the experiment was the examination of the worst possible case as many Peers as possible con nected to a single Rendezvous simultaneously talking to a single receiver Peer connected to the same Rendezvous The experiment took place as follows all senders sent a message containing the current timestamp once every ten seconds when the receiver received the message it measured the time occurred in between delivery The whole procedure involves many scripts listed below they must be lo cated in the same directory of the testShell build along with them several output files are created one for each Peer plus one that contains the logged experiment results Once the Rendezvous has been started by launching
76. ate destroy onActiveNlodeAdd onActiveNodeRemovel JIVES Class Diagram Appendix B JiveScript Shell Demo Code Snippet B 1 JiveScript Shell Demo JIVESCRIPT_VERSION 0 2 reset __uses org jives implementors engine shell __name Jives Basic Demo eie hora gt 2 cn El echo Welcome to Jives Basic Demo echo Ves gt ss soso snass soso soso sesos Wes echo This is a textual adventure engine that uses Jives Shell implementor Tana VESCICA echo Say help for a list of available commands SI I a e a O a UL gui org jives implementors engine shell GUIState getInstance dialogueModel org jives implementors engine shell SceneRenderState getDialogueModel bagModel new org jives implementors engine shell BagRenderState bag0 Define a listener inventoryListener new org jives events JivesEventListenerIntf handleEvent function jivesEvent action jivesEvent getAction if action instanceof org jives actions PortalAction if action getCurrentSceneId equals scene0 amp amp action getNextSceneId equals scenei org jives core JivesScene getMyself getProperties puti Gipiosiit onto Pomtian to scene O if action getCurrentSceneld equals scenel amp amp action getNextSceneld equals scene0 action getCurrentSceneId equals scenei amp amp action getNextSceneId equals scene2 org jiv
77. ature was not 152 Conclusions and Future Work a primary objective for the test Implementors Although not impossible to understand and use a command line interface is not what is generally considered friendly by a common user A better maybe graphical interface for loading script saving and restoring states and performing other common user operations would be preferable Concurrent activation action at present there is no way in which two Peers can concur to the activation of an Activable entity this is useful in the case that the distributed application state evolves differently according to who was able to perform the activation first for instance he or she might be the only user to receive a certain item from the entity Usually the application evolves according to the logic of the script which is the same on all the Peers but it s not shared among all the Peers Ideally a solution would be to include the information about the time of the entity activation in the RemoteActiveNode properties and handle the concurrency locally among all the playing character This would require sharing a timestamp and keeping every Peer synchronized JiveScript generation tool the Netbeans plugin 15 to ease JiveScript editing is only a starting point JiveScript entities definition apart from the SIMs implementation is very rigid A possible line of development would consist in writing a Netbeans plugin that exposes a purely graphical i
78. ayer Online Games MMOG 7 in which the huge number of Clients connected requires a high computational powered server architecture responsible to manage all the game state computations The drawback of this model is its non scalability as the number of participants in a Virtual Environ ment increases the server works as a bottleneck Even if additional Servers are used the delay due to additional communication overhead in servers is inevitable 35 Technological background 11 2 11 Peer To Peer Peer To Peer networks involve two or more computers sharing individual resources These resources are available to every computer in the network Each computer acts as both the Client and the Server meaning that all the computers on the network are equal not requiring any additional coordination entity such a cen tral Server and not delaying transfers by routing via Server entities Recently Virtual Environment middlewares such as ATLAS 35 Mediator 20 and Hydra 10 implemented a Peer To Peer architecture in order to face the scalability issues related to the Client Server architecture 2 12 JXTA Juxtapose JXTA 54 is an Open Source Peer To Peer protocol specification working through a set of XML messages which allow any device connected to ex change messages and collaborate independently of the underlying network topol ogy Implementations of JXTA 54 are available for Java SE C C C and Java ME The peculiarity of JXT
79. be Client Server based or a Hybrid architecture in order to meet all the requirements of the application in development In addition one of the most important reasons that led us to the realization of this new version of the JIVES framework is the fact that by analysing the existing products on the market we realized most of them are aimed at very expert users It is precisely for this reason that we decided to introduce in the realization of JIVES the possibility of using a scripting language the JiveScript through which also those who are not expert in programming have the possibility to create their own 3D application using our framework JIVES lets the developer choose to code an application directly in the Java 51 language or by using our scripting language The best choice is obviously somewhere in between by coding in the Java 51 language the developer can create new Jives modules called Implementors in which there is the actual implementation of some features needed by his application such as a Presentation implementor and a Networking implementor while the whole logic of the application can be coded directly in JiveScript In that way JIVES benefits from a large re usability the next time that it is necessary to develop an application that should handle similar virtual worlds for example any art gallery the developer will need to write only the application logic using JiveScript since the art gallery visualization code has been
80. bine them In order to do so the underlying data structure of a bag known as the Bag Graph not only must carry the information about combina tions but must also define if a combination is accepted thus we introduce the concept of HotSpot HotSpots are physical locations or descriptive attributes or eventually other entities that are attached to bag items and the combination of two items is defined by mean of matching an hotspot from the first item with an HotSpot from the second one Figure 5 2 shows a simple Bag Graph that defines three bag items a nylon wire a wooden stick and a hook and the necessary combinations to obtain a fishing rod Please note that while bag items are nodes of the graph HotSpots are the arcs A node can have many outgoing arcs but either zero or two incoming Design and Implementation 31 fishingRod L S stickWithWire S lt nylonWire woodenStick hook Figure 5 2 Bag Graph Example arcs in the case it has incoming arcs those identify the two parent nodes and the previously mentioned node is the result of their combination Also some arcs are dangling they are useless in terms of combination definition but yet they are present so that the puzzle solver has to include them in his her reasoning Each arc in Figure 5 2 is labelled with a textual attribute describing which part of the object is physically interested in the combination for example the wire edge with the stick tip
81. can even make use of a specific application to write the code instead of writing it directly In order to facilitate the developer we published a NetBeans plugin 15 so that it is possible to take advantage of the instant code auto completion feature As mentioned by White Related work 21 in 72 the choice of adopting a scripting language provides an additional layer of security JiveScript can be executed in a sandbox in which the developer is free to test his application changing several features and properties of the entities by means of scripting When the script is complete and not modifiable anymore the developer can block the sandbox mode in order to avoid that other users change the script even minimally Chapter 4 Motivations and targets Building a Virtual Environment is an extremely challenging and resource consum ing task Indeed many of the discussed related work are thesis per se involving on the whole years of research and teams composed by several people that co operate in order to create a commercially exploitable software Our approach to the problem cannot be seen as an universal solution fully working and efficiently performing this would require much higher costs in terms of time and human and hardware resources than we could afford in the immediate The main objective of this thesis can be found in achieving a general simple and versatile solution We perceived this objective as a design challenge and pu
82. cially the mouse input In particular due to the fact that the mouse pointer cannot be captured there is no longer the possibility to correctly manage the camera by using the mouse The user however has the possibility to manage the rotation by means of the arrow keys of the keyboard so as to overcome this issue In the Combination Screen the items can be correctly manipulated by holding the left mouse button on the desired object and rotating it using the arrow keys Same applies to translation when the right mouse button is pressed In order to test the network strength an experiment has been done by using both a LAN connection and an Internet connection In the first case a Rendezvous has started the ME 31 Test Demo incrementally at one minute interval a new peer executed on a physical machine has been set up to connect to the Ren dezvous up to obtain a scene shared between a Rendezvous and nine peers Up to a Rendezvous and five peers the network has performed well maintaining a low lag level while increasing even more the number of connected users results in a degradation of the network that can also lead to have a network lag of more than a second In particular the minimum lag observed was 0 6 seconds while the maximum one 2 1 seconds In the second case the execution of the experi ment using an Internet connection the network behaviour is very similar except Performance Metrics and Evaluation 133 of course an incre
83. combination helper algorithm The rotation represented in Figure 5 6 reaches the objective of putting the HotSpots on the 22 plane ME 31 reference system is right handed by having the chosen HotSpots face each other toward the origin which is set to be the median point of the two objects pivot on the axis In order to accomplish this it infers the angle of rotation from the y coordinate of the HotSpot in its local object space because this value is the arctangent of the unknown angle in the case that the coordinate is negative it takes the opposite of the result There is uncertainty whenever the rotation brings the HotSpot to face outward from the centre to resolve to the right placement the rotation is performed two times taking in account the resulting z coordinate of the HotSpot the second time a rotation angle of 7 is applied to the Y axis The right rotation is the one that 52 Design and Implementation minimizes the distance from the centre on the 7 axis in Figure 5 6 de is preferred to di At this point the situation is that one depicted in Figure 5 7 where there might be an offset on either or both the 7 and the Z axis A compensating translation 0 OF 07 is applied so that the two HotSpots lie exactly on 7 Ay Ny Figure 5 7 Translation step of the combination helper algorithm Overcoming JXSE v2 6 single Peer limitation By design prior to v2 7 there was no possibility of restarting the netw
84. continuum Between the two extremes of the continuum the pure Real Environment and the pure Virtual Environment there exist numerous variations both theoretical and applicative which mix to various degrees the elements of both the Real and Virtual Environments the spectrum in which this takes place 2 Introduction is commonly referred to as Mixed Reality Mixed Reality applications can be based on real elements with the addition of a number of synthetic ones generated by the computer in which case the talk is of Augmented Reality Alternatively the application can be almost entirely based on a synthetic environment with a number of real elements supporting it in which case it is referred to as Augmented Virtuality Virtual Environments applications can be extremely different from each other leading to a categorization into four main classes e Collaborative Virtual Environments CVEs describe Virtual Envi ronments that involve more than one user with avatars interacting with each other With high bandwidth and Internet access Virtual Environ ments that allow for greater multi user interactivity have become widely available in recent years e Immersive Virtual Environments IVEs increase the user s sense of presence actually being within it IVEs typically require special equipment such as a head mounted display or a project equipment situated in a room IVEs track a user s head and body position facial expressions and
85. ction to perform 0 Performing action Open 0 CATEGORY_DEFAULT 1 received Which category 1 coin x2 Ready I Figure 6 18 Managing the Item Inventory HotSpot through which it is possible to bind the item to another one If the combination is the one provided by the JIVES developer the user will receive a new item obtained from the combination of the two original items The whole procedure is shown in Figure 6 19 It is possible also to freely chat with one or more other users by activating them and selecting the Talk action Note that in order to activate a PC differ ently from the elements that are predefined in the scene the user has to use the activate command by defining the name of the PC enclosed in double quotes because there is no local variable that refers to them Figure 6 20 represents a chat between two PCs The JIVES Shell Demo let the user also trade items with NPCs and PCs this is possible by activating the other user or the NPC with the activate command and selecting the trade action In the case of trading with a NPC the user has to select before requesting the trade the items that he wants to exchange and then 100 Development and Usage Where do you want to move 2 You are now near Coffer Ready activate scenelCoffer 0 Open coffer 1 Cancel Which action to perform 0 Performing action Open coffer Received a wooden stick a nylon wire and two hooks
86. d in short models Implementing those interfaces the programmer defines the appropriate behaviour for his virtual environment Both Java 51 and the scripting API javaz script 52 JavaScript support inline instantiation of interfaces and using this approach it becomes possi ble to inject programmer s code into the system architecture For example models of any Activable present the getActivationEvent virtual method where it s pos 56 Design and Implementation sible to specify which kind of event will by fired by the activation being this a crucial step for the application logic One could write the whole models in JiveScript but this gets rapidly infeasible as the complexity of the application raises The typical approach is to encapsulate the most of the application features into the implementors and rely on the methods they expose when writing the application logic in JiveScript By doing so the same good written general enough implementors can be use to create a huge amount of different application scripts Persistence Layer JIVES allows to save and load state snapshots of its register Under the hood ev ery registered object extracts its field data into a proxy object one of the package org jives core persistence not the whole object is extracted due to serialization and redundancy issues but a subset of the fields that characterize its state Then the proxy object is saved in an object database The way back
87. d by the JIVES Peers to exchange messages Each Peer both a normal Peer and a Ren dezvous Relay cycle constantly publishing its own Advertisement and looking for Advertisements of other peers as shown in Code Snippet 5 6 Messages are sent through a pipe communication channel This channel brings messages without any kind of filtering operation when a Peer sends a message all the Peers listening the given communication channel receive that message Obviously the developer can choose to use this kind of configuration or implement a specific Interest Management Interest Management is the term commonly used to describe restricted message dissemination between objects or avatars using Virtual Environment division According to Morgan 39 Interest Management is classified into two main categories e Region based Approach the Virtual Environment is divided into well defined regions that are static in nature The recipient of a message is lim ited to only interested participants within the same or neighbouring region as the sender When an object traverses a region boundary region member ship must be updated JIVES is particularly predisposed to implement this kind of approach when developing a JIVES Inventory based Virtual En vironment application the developer by creating a new Networking Layer Implementor has the possibility to implement a division of the whole logic of application according to a specific number of scenes or rooms whic
88. d content creation In some cases the particular requirements of each game usually involves significant changes in the code leading to total re development of the game engine The main problems mentioned by Oliveira 46 which have affected the development of Virtual Environment systems during the last decade are here reported e Non Extensibility The design of most Virtual Environment systems is tightly coupled with the initial requirements thus resulting in monolithic architectures where any changes or modifications are infeasible The ar chitectures of more recent versions of some systems do present a modular design but continue to make it difficult to extend the core functionality if it was not foreseen in the original design Thus any changes require signif icant if not total re engineering of the underlying system In most cases the most cost effective solution is the creation of a new system e Steep Learning Curve The complexity of a Virtual Environment sys tem with its tightly coupled nature makes it difficult for a developer to haul any benefits without becoming an expert Unfortunately the learning curve associated to a system is traditionally exponential This results in a selected few being sufficiently proficient with a particular system normally the creators and maintainers Recently the adoption of different scripting languages has improved Virtual Environment development making it more efficient and accessible
89. d the Scene and Interacting witha NPC 98 6 18 Managing the Item Inventory 004 99 6 19 Combining Two Items through HotSpots 100 6 20 Free Chat between two Playing Characters 100 6 21 Trade between two Playing Characters 101 6 22 Network Settings Graphical User Interface 103 6 23 JIVES JiveScript Console cada sla do fab e 105 6 24 JiveScript ME Demo Starting Scene 106 6 25 JIVES Peer ME Network Configuration Settings 108 6 26 A second user joins the Scene 108 6 27 Interacting with a NPC 2364 d cil SARS eae eS eS 109 6 28 Dialogue with a NPC ri la elke Pe elke Pod 110 O20 ha bine witha a e A pa Ap ela 110 6 30 Inviting POG s a a ee Ra eda ala 111 6 31 Activating the Artifact lo o Sa a Dee Dea 111 6 32 JIVES Item Inventory Graphical User Interface 112 6 33 Selecting the Items from the Inventory 113 6 34 JIVES Combination Screen urli a falena ata eta 114 6 35 A successful combination pi A A Ae A Ee a 115 6 36 A Trade Request ax aa alk e483 Rava aaa 115 6 37 The Notification that Trade Request has been accepted 116 6 38 Trading the selected Item cra ar a 117 6 39 Confirming the Trade vids ale te ea aa SAR 117 6 40 Trade is complete ppi Wei Wes aliene are ROE 118 LIST OF FIGURES VII 6 41 The user has received the new Item 118 6 42 Trading with a NPC bg ety lan a ke
90. de Snippet 6 3 JIVES Network Configuration Default Settings lt zml version 1 0 encoding UTF 8 standalone no gt lt network gt lt jives gt lt jivesUsername gt JivesUser lt jivesUsername gt lt jives gt lt user gt lt proxyHost gt lt proxyPort gt lt proxyUsername gt lt proxyPassword gt lt user gt lt server gt lt urlHost gt http jives sourceforge net rendezvous lt urlHost gt lt urlSecretKey gt http jives sourceforge net access getSecretKey php lt urlSecretKey gt lt httpsUsername gt lt httpsUsername gt lt httpsPassword gt lt httpsPassword gt lt server gt lt lan gt lt rendezvous_ipv4 gt lt rendezvous_ipv4_port gt lt rendezvous_ipv6 gt lt rendezvous_ipv6_port gt lt lan gt lt interface gt lt netInterface gt lo lt netInterface gt lt interface gt lt internet_lan gt lt choice gt lan lt choice gt lt proxy gt false lt proxy gt lt ipv6 gt false lt ipv6 gt lt internet_lan gt lt network gt The user has the possibility to modify the name of his avatar in the Vir tual Environment by modifying the jivesUsername field or setup the kind of connection by typing in the choice field lan if the user wants to execute the application in a LAN network or internet if the user wants to use the Internet connection In the first case the LAN connection the user has the possibility to choose if he wants to start the JIVES application ass
91. decreased from 10 to 1 Even better results can be obtained by integrating in the JIVES framework some important message exchange reduction optimizations such as an Aura based Interest Management 39 or a Predictive Interest Management 39 or a revisited version of the Delaunay triangulation 8 e Scalability improvement in order to extend the support of the JIVES framework also for massively multiplayer applications and improve its scala bility some further optimizations can be explored such as Dynamic Broad cast Tree technique 10 e Middleware structure at the moment the Implementors code is not sub ject to any guideline There is simply the need of an engine and of a network interface actually there can be more rigid approaches that will allow a pol ished Middleware structure that needs to be defined at the expense of a bit of the programmer s freedom This should bring some advantages like reducing the time of coding of new Implementors and keeping their code as much clear and integrated with the system as possible thing this one that does not really apply to the test Implementors With respect to this point there will be the need to introduce an Audio Implementor in order to have a text to speech feature for in game dialogues and sounds in the 3D Environment jME 31 can be extended to this but this work implies to define a better Middleware structure e User friendliness even if undoubtedly important this fe
92. derer gui id stickWithWire categories found combines new org jives implementors engine jme HotspotRenderer com jme3 math Vector3f 0 42 5 38 2 59 1 Ho Aaa l model new org jives implementors engine jme BagItemRenderer Models stickWithWire stickWithWire mesh xml 0 05 A nylon wire tied to a wooden stick JiveScript ME Demo 171 commonActionsRenderer gui id fishingRod categories fishing 1 combines model new org jives implementors engine jme BagItemRenderer Models fishingRod fishingRod mesh zml 0 05 A hand crafted fishing rod commonActionsRenderer gui Jr bagModel bagCombiner Define actions bag0 bindCommonActions gui dialogueltem Jives get coin org jives core JivesBagltem ii DOOR BO GOGE i 2 02 2 22220209 see ana Sa oS SSeS SSS SSS Sas scene2PortalTol new org jives core JivesActiveNode scene2PortalToi new org jives implementors engine jme PortalRenderer Models portal portal mesh aml new com jme3 math Vector3f 60 6 70 DE scene2 addActiveNode scene2PortalTo1 scene2PortalTo1 bindAction new org jives actions PortalAction scene2PortalTolAction scene2 scenel DE A enni scene2Pond new org jives core JivesActiveNode scene2Pond new org jives implementors engine jme WaterNPCRenderer Models pond pond mesh axml new com jme3 math Vector3f 190 7 4 10 12 scene2 addAct
93. derive a stick with an attached wire and also nodes are represented by a textual description But this is only a possible model of this bag graph because in a visual environment for instance the nodes would be 3D models while HotSpots would be predefined volumes located in the models space 5 1 2 Event Driven Architecture The struggle for generality implies that the system must provide a certain degree of flexibility toward application specific behaviours as long as it is not possible nor convenient to foresee each and every possible scenario directly in the framework design This is the main reason why we introduce the events the most basic feature of a work flow management system 74 Actions are not simple tasks or routines that get executed unconditionally and immediately after an activation 32 Design and Implementation has been issued but events triggered by the activation of any activable entity instead The advantage that this design bring is immediately comprehensible events can be intercepted delayed conditionally evaluated and consumed concatenated inhibited perhaps while the correspondent action is executed or trashed accord ingly The top level application can exploit the event based approach to implement its own logic upon every activation both issued by the end user or by the sys tem itself without breaking the encapsulation of the lower levels and remaining completely agnostic about the internal handling
94. during state re store the proxy object is read from the database and the respective registry entry is updated The advantage of this approach is the decentralization of the distributed ap plication state Of course the main issue is that of avoiding local and extraneous modifications to the database so that the integrity of this distributed state is kept The most obvious solution is that of encrypting the database and to reach this objective the system must obtain a secret key that cannot be generated locally and that the peer must not be aware of To achieve this the Network Implemen tor must contact a remote location identify the peer with his credentials account and password and return a secret key to be used for encryption As security measure this connection must happen in HTTPS so that it is possible to avoid man in the middle attacks Design and Implementation 57 Actions and Events Management System JIVES performs event processing and other network related operations every time the doLoop method is called in the application main loop Actions and events are tightly coupled because every time an activable entity is activated by mean of an action an activation event is fired But events can also by fired independently from entity activation at any time to tell to the program logic that something has happened and consequently the action bound to the fired event must be executed Event listeners can be registered in order
95. e gt 60000 nodesToRemove rendezvous programFilesToKeep program Server side Rendezvous directory active page Server side Rendezvous directory active page 181 foreach nodesToRemove as node node gt parentNode gt removeChild node files scandir APPLICATION_DIRECTORY foreach files as index gt file foreach programFilesToKeep as programFile if strcmp file rendezvous_ programFile xml 0 4 unset files index Ip foreach files as file if is_file APPLICATION_DIRECTORY file unlink APPLICATION_DIRECTORY file doc gt save rendezvous xml echo Query inactive rendezvous completed break case updatetime if strcemp _GET token md5 _GET pid _GET program 0 doc new DOMDocument doc gt preserveWhiteSpace false doc gt load rendezvous xml doc gt formatOutput true root doc gt documentElement rendezvous_list root gt getElementsByTagName rendezvous foreach rendezvous_list as rendezvous program rendezvous gt getAttributeNode program gt value MD5 rendezvous gt getAttributeNode md5 gt value IPv4 rendezvous gt getElementsByTagName ipv4 gt item 0 gt textContent IPv6 rendezvous gt getElementsByTagName ipv6 gt item 0 gt textContent port rendezvous gt getElementsByTagName
96. e Activate me using the Trade action actions new org jives actions StartDialogueAction Jives generateld sceneONPCODialogue0Dialogues Aw question Can I trigger any action during a dialogue answer Of course Here an action ts triggered and then the dialogue continues actions new org jives core JivesAction inDialogueAction new org jives sim JivesActionModelIntf execute function jivesEvent gui notification Light blinks and walls tremble OO e DI getDescription function return In dialogue Uco Es render function jivesRenderableIntf gui notification this getDescription DDE new org jives actions StartDialogueAction Jives generateld scene0NPCODialogue0Dialogues question I ve understood thank you answer You re welcome actions new org jives actions StartDialogueAction Jives generateld scene0NPCODialogue0Intro dialogueRenderer dialogueRenderer Bind dialogues to NPC sceneONPCO new org jives core JivesActiveNode scene0NPC0 new org jives implementors engine jme NPCRenderer Models 0to 0to mesh axml new com jme3 math Vector3f 160 11 8 35 JiveScript ME Demo 175 scene0 addActiveNode scene0NPCO sceneONPCO bindAction new org jives actions StartDialogueAction scene0NPCODialogue0RootAction scene0NPCODialogue0Root getId Bind trade to NPC tradeltem Jives get
97. e a aa lieta 119 6 43 The Certificate Request LL 121 TL Start up experiment ostia id bla dic epa arpa era 131 7 2 Network Load Performance Measurement 136 7 3 Total number of message transmissions for number of nodes 137 7 4 Web browser usage 2 2 2 2 00 ee ee 147 Pool cd Vie Class Lae A A a 157 List of Code Snippets 5 1 Proxy connection cs a Lili ahh een 37 5 2 JIVES Pipe Advertisement 40 5 3 Inline Instantiation a a dd inte i E 41 5 4 Bag definition eci cu ia fed E dee Eee Da 44 5 5 Dialogue definition o Lu alloro ia dt leale 46 5 6 Rendezvous Relay run method 63 5 7 NetworkMessage constructor o oo a 66 5 8 Nifty GUI Multithreading y ss a dele dia 71 Galt TestJMEApplet tte da dt a Ae ce 83 6 2 Applet builder Bash Script dado ie e dota 84 6 3 JIVES Network Configuration Default Settings 91 6 4 JIVES Peer Network Configuration Settings 97 6 5 SNe Policy Filen as dug Mags EMA La A A 121 6 6 uses and name dileGtivesi causi ee n eR ROP 122 0 Event listener a aiig da a ia ira eet 123 6 8 Shell Items combinations 5 ede e e a e heb OR 124 6 9 jME Items combinations e es E Sue aa YR 125 6 10 Scene Model Definition ee ar I e we OS 126 6 11 A predefined Dialogue ada are a 127 6 12 Trad witka NPO e pacsi da ds Na tes ale A 128 7 1 The Network Test Receiver Script 134 7 2 The Network Test Starter of Sender Scripts
98. e application has been loaded the user s avatar will be in the opening scene as shown in Figure 6 24 The statistic nodes that appear in the left bottom corner of the application window can be hidden by typing the F11 key of the keyboard 800 jMonkey Engine 3 0 JivesUser Frames per second 59 Figure 6 24 JiveScript ME Demo Starting Scene The ME 31 Implementor provides all the operations available in the Shell Implementor The user can move his avatar by using the WASD keys of the Development and Usage 107 keyboard as typically in First Person Games and interact with the elements in the scene by using the right mouse button The camera can be rotated around the avatar by left clicking the mouse and dragging it in the desired direction or by using the arrow keys of the keyboard The user can also zoom in or out by using the middle mouse button If an other user joins the same JIVES Virtual Environment application his avatar will appear in the initial scene The procedure to join a running JIVES application is similar to the one al ready seen for the Shell Implementor but in this case the user has a comfortable Graphical User Interface to set up correctly the network settings From the point of view of the joiner user once JIVES has been started the JIVES Network Con figuration Settings have to be accessed by typing the Esc key of the keyboard and selecting the Network settings button If
99. e code instead of machine code specific to the computer system the user is executing The Java 51 compiled code is executable on any processor and system it is sufficient to have the Java 51 Virtual Machine installed Because of this JIVES reaches a great portability it has been successfully executed on Windows MAC OS X and Linux Actually it can also be considered a Web VE when running as an applet From a technical point of view the matter is a bit less enthusiastic Prior to reducing the number of classes loaded by the MultiInstanceEndpoint JXSE 54 class loader unless the start up time the mean value of the measured times was 21 52 could be considered very good the 3D visualization engine required big amounts of memory to run a 3D Virtual Environment application developed by using the JIVES framework The optimization improved both the start up time the average time now is 15 56 and the memory consumption reducing the latter by 50 Nevertheless an high number of concurrent Peers can lead to system degradation Such heaviness in the execution is not to be ascribed to JIVES but to the ME 31 visualization engine Using a medium high performance hardware JIVES runs optimally along with ME 31 In particular minimum requirements are 1 GB RAM and a 512 MB graphics card while recommended requirements are 2 GB RAM and a 1 GB graphics card Another problem regards the network scalability when an high number of Performance
100. e syntax of the language Both users have loaded the script without any particular problem Once loaded the script they were asked to perform some operations inside the Virtual Envi ronment The actions that were performed correctly are moving around the Virtual Environment chatting with a NPC and a PC obtaining items from the NPC managing the Inventory trading with a NPC saving and loading the state application When it came to combine two items both users were in difficulty to understand the combination mechanism but both have completed successfully the combination Also trading with a PC was found to be unintuitive and difficult to properly execute The newbie user in this case failed in executing correctly the trade Another factor that results from the experiment is the fact that the users had some difficulties in remembering the different commands needed to use the application The second experiment consisted in executing JIVES and load the jME 31 Test Demo Thanks to the experience gained during the first experiment both users have proven immediately to be much more responsive Once started JIVES they were asked to configure the network settings in order to start the Demo as a simple Peer Both the medium expert and the newbie users were able to configure the network settings by means the Nifty Graphical User Interface without any particular problem When executing the ME 31 Demo both users performed in
101. eONPCODialogueODialogues question Can you give me an item to put in inventory answer I can but for demonstration the limit has been set to two items only actions new org jives actions BagItemAction Jives generateld dialogueltem bag0 E new org jives actions StartDialogueAction Jives generateld scene0NPCODialogue0Dialogues question Can I trade items from my inventory answer Yes we can trade Activate me using the Trade action actions new org jives actions StartDialogueAction Jives generateld sceneONPCODialogue0Dialogues 166 JiveScript Shell Demo question Can I trigger any action during a dialogue answer Of course Here an action is triggered and then the dialogue continues actions new org jives core JivesAction inDialogueAction new org jives sim JivesActionModelIntf execute function jivesEvent gui notification Light blinks and walls tremble AO O MOORE a me OER getDescription function return In dialogue action F render function jivesRenderablelntf 4 gui notification this getDescription DOE new org jives actions StartDialogueAction Jives generateld sceneONPCODialogue0Dialogues question I ve understood thank you answer You re welcome actions new org jives actions StartDialogueAction Jives generateld scene0NPCODialogue0Intro y dialogue
102. eScript v 0 2 Shell ox 123 MB memory 66 MB free This script name is script MTMxOTAOMDUWNjE1NQ Ready Figure 6 12 Shell Implementor Starting Screen Linux distribution Once a terminal has been started the commands the user has to type are the same ones used in MAC OS X the cd command must be used to reach the JIVES directory and the command java jar jives jar to launch JIVES The procedure has been successfully tested using a Linux Fedora 15 distribution virtualized by Parallels Desktop in a MAC OS X Lion Environment Under a Windows operating system the procedure is almost the same The user has just to click the Start button then digit the cmd command under the run option This command executes the Command Prompt a terminal for Windows operating systems Once the Prompt has been started the user has to move to the right directory in which JIVES is located using the cd command and then execute JIVES typing the command java jar testShell jar where testShell is the name of JIVES application file The whole procedure is reported in Figure 6 13 This procedure has been successfully tested using a Windows Seven Professional 64 bit operating system When running a JIVES Shell Virtual Environment application in order to 90 Development and Usage Figure 6 13 Starting JIVES from Windows Command Prompt set the network configuration the user has to set it manually This means that the user has to open with any te
103. ean flag telling to enable or disable script ing 48 Design and Implementation 5 1 6 Critical conditions and their resolution This section briefly describes many situations that put the design under stress and how those issued were managed or resolved confirming the validity of the work done so far TradeltemsAction Peer disconnection When a Peer disconnects during a trade action it can return to a persistent state right before the transaction happened on its reconnection if the application wishes this to happen So there s no problem of data loss on the disconnecting part but the counterpart should revert the transaction locally Figure 5 5 is a sequence diagram that describes this automatic procedure Swap items COMMIT rollbackThread start endMessage NetworkAddress NetworkMessag i ndMessage NetworkAddress NetworkMessage Dest disconnected receiveMessage NetworkAddress String DEST COMMIT endMessage NetworkAddress NetworkMessag Lg Rollback sendMessage NetworkAddress NetworkMessage abort Figure 5 5 TradeltemsAction rollback Design and Implementation 49 Initiator part might or might not have received destination commit acknowl edgement DEST_COMMIT before destination disconnected what matters is that destination will not send back the INIT COMMIT acknowledgement and this means that Initiator cannot go into INITAND_DEST_COMMITTED state before rollb
104. eans of the addition of new Implementors and custom Performance Metrics and Evaluation 143 actions in the Middleware Layer One of the key points specified in the design phase was the will to create a scripting language that would allow to develop easier JIVES applications As seen in the test experiments and in our personal experience we can assert that this goal was largely achieved if the developer is not interested in creating new Implementors he can develop a JIVES application making use of the JiveScript only Once he becomes familiar with the scripting language he will be able to write the application in an easier and faster way Another feature of which JIVES can be proud is the possibility to define the whole logic of an application in the script without having the need to write a single line of Java code Since the design phase we set out to build a framework that could be dis tinguished from the others This was possible thanks to the implementation of a fully integrated Item Inventory Management System which permits to manage and combine the Inventory items in a way never seen before Through the defi nition of several HotSpots for each item JIVES offers the possibility to combine items in a more complete and meaningful way compared to other Virtual Envi ronment systems The test experiments have shown that combining the items together in a 3D Environment thanks to the HotSpot combination helper requires no practice at a
105. ective child and the model of the item Then using the makeBag JiveScript command the inventory is created empty with the appropriate underlying Bag Graph 5 2 2 Networking Layer The Networking Layer has the responsibility to retrieve resources across the net work and to manage all the functionalities pertaining networking operations The Networking Layer implementation provided by default in the JIVES framework is completely based on the JXTA 54 Peer To Peer technology JXSE The JIVES Networking Layer is implemented using the Open Source Peer To Peer JXTA 54 technology in particular its Java 51 version JXSE Being JXTA a Peer To Peer technology its functioning is based on the distinction between Rendezvous Relay and Peer A Rendezvous is a super peer with the responsi bility to assist normal peers and handle message broadcasting a Relay is a peer used to store and forward messages between peers that do not have direct con nectivity because of firewalls or NAT a Peer participates in the Peer To Peer network implementing only the basic JXTA functionalities The JIVES imple mentation provides a breakdown of Peers into two main categories normal Peers and Rendezvous Peers with Relay capabilities In that way in order to have a fully working network it is sufficient that there are at least two peers one of which is a Rendezvous Relay peer The JXSE Implementor has been designed 62 Design and Implementation to ful
106. ediately the user s avatar will be teleported in the next scene Figure 6 31 shows the activation of an Artefact of the scene 110 Development and Usage en Monkey Engine 3 0 Can Itri understood thank you 1 Frames per second 25 Figure 6 28 Dialogue with a NPC jMonkey Engine 3 0 wind JivesUser2 enters the chat JivesUser JivesUser enters the chat JivesUser2 JivesUser Hi Howare you Monkey Engine 3 0 JivesUser2 I m fine Thanks Chatwindow x yr 3 JivesUser enters the chat JivesUser JivesUser2 enters the chat JivesU ser2 se r2 Trio JivesUser JivesUser Hi How are you JivesUser2 I m fine Thanks Invite Figure 6 29 Chatting with a PC Development and Usage 111 Figure 6 30 Inviting a PC eoo jMonkey Engine 3 0 JivesUser Figure 6 31 Activating the Artifact 112 Development and Usage Being JIVES an Inventory Based Virtual Environment system the user has the possibility to collect items from the scenes and manage them inside his inventory In order to open the inventory the user s avatar must be activated by clicking the character with the right mouse button and selecting the Open inventory action The Item Inventory Management Graphical User Interface will appear as shown in Figure 6 32 The user has the possibility to scroll through the various items examining or selecting them 800 jMonkey Engine 3 0 Combine IO woodenStick x1 h
107. eed to be implemented so that it s possible to activate the Bag and the items contained in it The graph is first built by defining each node of the combinations tree then it gets queried when trying to combine two items represented by two respective nodes in the graph The final shape of the Bag Graph is a forest of directed graphs in which each node that represent a combination of two parent items has either zero or two incoming arcs the parent items If the node has no parents it is defined to be a root while every child which is not parent for any other combination is said to be a leaf A BagGraphHotspotIntf is associated to each arc of the graph this information is useful during interactive combination to give a more realistic scenario in which not only two coherent items must be selected to be combined but they can present many hotspots that match a combination result Moreover the nodes of the graph are tagged with one or more labels that Design and Implementation 61 subdivides Bag Items in different categories to improve searching and indexing operations At any time new nodes can be added to the graph as well as bound nodes can be removed in cascade to fully support the dynamic changes in the inventory structure Just like dialogues Bag Graph is defined in JiveScript using JSON For every Bag one defines a list of Bag Items specifying their id the categories they belong to every possible hotspot and the id of the resp
108. egory e bindNodel e addchildi e getcategories freezel e getcombinationResulti getcategoriesi e getcombinationresult getchildren e getNodeParents getHotspotForchild e getNodesinCategorvi e getttotspotsi e isNodeDefinedi getido e unbindNodel e isincategoryi removeCategoryi e removechildi e unfreezel amp NetworkSenderReceiver amp DialogueRequesti freezel getactions getansweri getidl getParentidi getPropertiesi getQuestion getRendereri getSourceldi getTargetidi islssuedt setActionst setansweri issued setparentidi setPropertiesi setQuestioni setRendereri setSourcel setTarget unbindRequesti unfreezel Remotelivesactioni executel getDescriptioni getMessage getReceiverNamel getReceiverPid render jivest doLoopl fireevent flushRegisters generateldl geti lt T gt amp getEnginel amp getNetwork0 getrransactioni getversionl amp listkegistryt loadSnapshot puti amp putt registerEventListener registerTransactioni removel amp removel removeEventListener removeTransaction S saveSnapshot setenginel setNetworkl JivesDialoguel freezel getidi getRequest toStringl unfreeze RemoteactiveNode getactivationEvent getProperties isActivablel onPrapertyUpda
109. ementation that allows to store XML data It is possible to use any XML tool to provide and access these data Support classes for Apache Xerces J and Xalan J are included 2 15 C C 12 is a statically typed free form multi paradigm compiled general pur pose programming language Today because it is object oriented and compiles to binary the most popular game development language is C 12 Because of this the majority of commercial computer and video games are written primarily in C 12 2 16 Java Java 51 is a platform independent object oriented language that aims to the development of applications to run in network environments and the Internet Nowadays Java 51 can be executed by most of the existing browsers 34 47 through the Java Web Start technology Most of the Virtual Environment VE middlewares 47 45 36 33 make use of Java 51 as the primary language Nev ertheless Java 51 has always been considered slower than other development languages such as C nowadays the performance offered by Java 51 when a 3D accelerated graphics card is used is fully comparable to C Ingles 30 investigated Java s performance for game programming showing that by the in troduction of the full screen exclusive mode in J2SE version 1 4 programs using Java 51 are able to access graphics hardware more directly The addition of full screen exclusive mode alone has increased Java s graphics performance speed 1
110. es core JivesScene getMyself getProperties ACASO AOS Mons cene ivi if action getCurrentSceneId equals scene2 amp amp action getNextSceneId equals scenei org jives core JivesScene getMyself getProperties PUDO Sai tono mt alos cene 2u 160 JiveScript Shell Demo if action instanceof org jives actions BagltemAction 4 if bag0 getQuantity coin lt 2 4 gui notification Listener Received action getItem Berico se 7 49 8 return false else Y gui notification Listener You already have enough coins return true if action getId equals openCoffer LEVA cofferOpened Jives get cofferOpened java lang String catch e cofferOpened Garsen if cofferOpened false Jives put cofferOpened true return false else gui notification Listener The coffer is empty return true return false dep getId function return inventoryListener Ip 8 Jives registerEventListener inventoryListener Define bago bag0 makeBag 4 bag0 it id apple categories received combines model new org jives implementors engine shell BagItemRenderer An apple received trading with that strange guy commonActionsRenderer gui A categories received combines new org jives implementors engine shell HotspotRenderer Useless hotspot null 1 model new org jives implementors e
111. essible in the directory Applications Utilities Terminal Once the Terminal has been started the user has to start the JIVES application by reaching the right directory where the application is located In order to explore the directories in the Terminal the user has to use the command cd followed by the name of the folder in which he desires to move For example if the pre compiled jar file is located in a folder called Jives on the Desktop the user has to type in the Terminal the command cd Desktop Jives Once the Terminal points to the desired folder the user has only to start JIVES by launching the command java jar testShell jar where testShell is the name of the jar file as shown in Figure 6 11 The procedure is successfully tested using a MAC OS X Lion operating system eoo Gives bash 80x24 e Last login Sat Oct 29 17 22 58 on ttys002 Simones MacBook Pro simonesegalini cd Desktop Jives Simones MacBook Pro Jives simonesegalini java jar testShell jar l Figure 6 11 Starting JIVES from Mac OS X Terminal Once JIVES has been started the Terminal appears as shown in Figure 6 12 Under a Linux operating system the procedure is quite similar to the one proposed for MAC OS X Because the number of Linux distributions is quite huge there is no reason to explain here how to start a shell or terminal for each Development and Usage 89 e090 LJ Jives java 80x24 2 eee JIVES v 1 0 0 Jiv
112. etween agents that share an Environment According to the MRIC model 66 modern Net VEs display little if any integration with the real environment while their degree of Released Reality and Immersivity differs according to the type of application 1 1 Development of a Virtual Environment sys tem A Virtual Environment presents a challenging problem with regard to the devel opment of an underlying system The problem domain presents itself being vast requiring diverse areas of expertise which may range from networks to psychol ogy This complexity makes the development of a Virtual Environment system a difficult task to achieve with a high cost in resources Oliveira 46 asserts that the wide applicability of a Virtual Environment such as scientific visualization socializing training gaming produce a set of requirements that make it very dif ficult to build a single system to fit all needs Traditionally the result has been the creation of monolithic systems that are highly optimized to a particular ap plication without possibility of re usability with a different purpose In the last decade the main trend in the Virtual Environment community has been for a new Virtual Environment system to be developed every time it was necessary to use one The trend in the games development industry is even worse where the 4 Introduction production cycles of each application traditionally involve game design technol ogy development an
113. etwork propagation is immediate However from Linux Kernel 2 6 the netem 136 Performance Metrics and Evaluation network emulation 28 was introduced as kernel module Thanks to netem 28 it is possible to simulate a network delay of 100ms 10ms having a random distribution issuing the command tc qdisc add dev lo root handle 1 0 netem delay 100ms 10ms To revert emulation just run tc qdisc del dev lo root As a side note it must be said that the same procedure can run on a Mac OS X if opportunely adapted In this environment the graphic user interface to the network module is called Network Link Conditioner The results obtained by the network load experiment are shown in Figure 7 2 50000 45000 40000 35000 Q S o 25000 Mi if ee Measured Delay ms 10000 e 4 5000 rag af r Number of Peers Measured Delay ms Sony Vaio Experiment Trend 1 Measured Delay ms MacBookPro Experiment Trend 2 Figure 7 2 Network Load Performance Measurement In order to decrease the number of messages per second sent by each peer a linear interpolation related to avatar movements has been coded in the Implemen tor Figure 7 3 shows the total number of message transmissions as the number of joining nodes grow comparing the results obtained before and after the opti Performance Metrics and Evaluation 137 mization It is important to remark that the statistics shown in Figure 7 3 do not
114. fferent Peers won t overwrite each others files Also senders are executed programmatically once every while and instructed to send messages to the receiver named peer0 Code Snippet 7 2 shows how they are started one after the other calling the testnet send sh script which actually executes the sender job as can be seen in Code Snippet 7 3 Performance Metrics and Evaluation 135 Code Snippet 7 2 The Network Test Starter of Sender Scripts path usr src eclipse jives out Path of the testShell build cd path for iin s100 do echo Starting peer nA i sh testnet send sh i amp sleep 30 done Code Snippet 7 3 The Network Test Sender Script bin bash ic SA then echo Specify index param exit fi arg 1 file arg output txt path usr src eclipse jives out function bot echo Jives getNetwork startNetwork test org jives implementors network jxse utils Tools md5Converter test while true do Search dest peer echo gt file echo lookAround sleep 1 found echo cat file grep c peer0 if found 1 then Dest peer found talk echo activate peer0 echo 0 time date s N 1000000 echo arg time fi Ponder next move sleep 9 done i cd path touch file echo gt file bot java jar testShell jar tee file Testing on localhost however does not give meaningful results because the n
115. function 4 activate onActiveNodeAdd function jivesActiveNode if jivesActiveNode getModelType equals org jives network RemoteActiveNode org jives implementors engine jme SceneRenderState setupRemoteDialogue jivesActiveNode org jives implementors engine jme SceneRenderState setupTradeAction jivesActiveNode bag0 function O 4 onActiveNodeRemove function jivesActiveNodeArray scene2 new org jives core JivesScene Scene 2 scene2Model Define a listener inventoryListener new org jives events JivesEventListenerIntf handleEvent function jivesEvent action jivesEvent getAction if action instanceof org jives actions PortalAction if action getCurrentSceneId equals Scene 0 amp amp action getNextScenelId equals Scene 1 4 position sceneiPortalTo0 getProperties get position if action getCurrentSceneId amp amp action getNextSceneld position scene0PortalTol if action getCurrentSceneId amp amp action getNextSceneld position scene2PortalTol if action getCurrentSceneId amp amp action getNextSceneld position sceneiPortalTo2 equals Scene 1 equals Scene 0 4 getProperties get position equals Scene 1 equals Scene 2 4 getProperties get position equals Scene 2 equals Scene 1 4 getProperties get position org jives core Jive
116. gestures and other information thereby providing a much information about the zone or the item of the Environment in which the user is focusing the attention e Massively Multiplayer Online Role Playing Games MMORPGs describe multi player games which are capable of supporting thousands of players simultaneously They are often based on fantasy themes 6 41 62 e Multi user domains MUDs are primarily text based environments that were the predecessors of modern graphical Virtual Environments In particular Collaborative Virtual Environments include a category of sys tems in which individuals cooperate in a network according to the paradigms of released reality placing these applications into a category referred to as desktop Introduction 3 virtuality or semi immersive virtuality in which the only two items that are necessary are a good graphics card and a good personal computer The advent of standards such as VRML for 3D representation on the Web have allowed to also develop other types of applications that are entirely Web based This category is often termed Net VE Networked Virtual Environments and also includes a sub group called Web VE Web Based Virtual Environments which consists solely of Environments that use Web technologies instead of own technologies The salient characteristic of these systems is that they are network based and therefore are essentially concerned with establishing strong collaboration b
117. gure 5 4 JIVES Networking Layer Architecture JXSEImplementor When JIVES runs a Virtual Environment application in the LAN mode only the private address is needed to connect Peers belonging the same LAN while Design and Implementation 37 in the Internet mode both addresses are needed the public address is used to reach the router the private address is used to reach the Peer behind the router If a user has a direct connection to Internet without passing through a router or when an IPv6 address is used there is no need of the distinction between the public address and the private address they coincide The basic functioning of the JXSEImplementor is shown in Figure 5 4 The JXSElmplementor does not take into consideration the JXTA 54 Proxy Peers because it has been designed to support Proxy connections in a different way in Java 51 there is the need to set only some system properties as shown in Code Snippet 5 1 Code Snippet 5 1 Proxy connection Reading networkConfiguration XMLConfigParser readProxyConfiguration Enabling the properties used for Proxy support System getProperties put prozrySet true System getProperties put prozyHost XMLConfigParser proxyHost System getProperties put prozyPort XMLConfigParser proxyPort Removing inactive Rendezvous queryInactive Querying the Rendezvous file queryFile scriptName scriptMD5 URL url new URL remote_url URLConnect
118. h can represent the regions of the Region based approach In that kind of config uration only peers participating the same room can message each other A variant of the Region based approach came to the attention within the last years with the growth of satellite technologies the management of the Design and Implementation 65 Peers of a Virtual Environment may be implemented through a geolocation mechanism in order to allow a specific Peer to interact with others Peers only if they are geographically close to him improving in that way the quality of the online experience or to allow a user to perform a certain action in the Virtual Environment only if he is physically at a given place on earth To achieve this result it would be possible to exploit the Rendezvous directory for the logical separation of Peers when they connect e Area Of Interest Approach each object or avatar is associated with an Area Of Interest or Aura that defines an area of the Virtual Environment over which an object or avatar may exert influence An Area Of Interest or Aura may be simply modelled as a sphere that shares its centre with the positional vector of the object or avatar it is associated with Nevertheless this kind of approach is more difficult to implement with respect to the Region based approach the developer may add this functionality to the JIVES framework by developing a new Networking Layer Implementor that encloses this feature A
119. he choice of MonkeyEngine 31 as the Presentation technology of the JIVES frame work is dictated by the fact that the MonkeyEngine 31 is a completely free and Open Source Java based game engine this means that it offers a lot of features that can be useful to JIVES such as collisions particle systems shaders terrain system and renderer abstractions An additional implementation of the Presen tation module has been done in order to have all the functionalities of the JIVES framework running also in a textual mode through the Shell Implementor the user can create a fully working textual Virtual Environment In addition to the Presentation module the Middleware layer includes also all the possible exten sions introduced by the JIVES developers such as new events and actions In that way JIVES can be expanded offering new customizations that also other developers can use in writing their Virtual Environment applications The VESLOM approach 45 defines the Application layer as a representation of the final Virtual Environment system that the user interacts with it contains all the components that are tightly coupled with the specific functionality and instantiation of the Virtual Environment For this reason the Application layer of the JIVES framework has been designed having in mind the idea to offer a new smooth and interactive way to write 3D Virtual Environment applications this is possible through the use of the JiveScript scrip
120. he JIVES framework is completely based on the Virtual Environment System Layered Object Model VESLOM approach 45 depicted in Figure 5 1 Universal Platform Networking Middleware Figure 5 1 Virtual Environment System Layered Object Model 28 Design and Implementation The choice to follow the VESLOM approach is due to the will to avoid the mono lithic design used by the Virtual Environment systems of the last decade in which each time a new set of requirements are specified a new Virtual Environment sys tem is designed and implemented At the contrary the VESLOM approach offers a novel methodology to develop Virtual Environment systems based on a strong layered component design The approach underlying VESLOM is to reduce the complexity in creating a new Virtual Environment system by dividing this com plexity into different layers each of them provides a specific functionality of the overall system As described in the VESLOM approach 45 the core functionality of JIVES lies in the so called Universal Platform module There is no need to adopt an entire system but only the Universal Platform and select the appropriate compo nents or build new ones to have a fully working Virtual Environment middleware In particular JIVES Universal Platform has been designed with specific function alities in mind in addition to the JIVES Core which represents the kernel of our framework the Universal Platform includes the Pe
121. he event pool as long as it s not happened then its action gets executed and the event is discarded e Keep always The event will be processed and possibly its action will be executed as long as its execution policy doesn t change The event processing usually happens immediately when the event is fired but as mentioned above this is not always the case because this behaviour can be influenced Moreover it s not always desirable to wait for the event process to complete before the main thread execution continues Those cases are regulated by the following flags e Execute As Soon As Possible ASAP The fired event will stay in the events pool until JIVES loop starts and it will be processed in that loop e Fork and execute The fired event will execute its action in another thread so that the main thread will not be kept waiting This comes handy while waiting the user input which is a blocking operation in some calls to the SIMs When it comes to actions JIVES offers a minimum set of common actions and a hierarchy of Activable Objects like Active Nodes Bags Bag Items extends this class that allows actions to be performed on them and that keeps trace of their kinship like the case of activable items in an activable inventory One could possibly extends himself this hierarchy to define other types of activable entities that have not been covered so far Common actions are those expected features like activation of a
122. he virtual environment Of course one is allowed to write as many SIMs Structured Interactivity Mod els as needed directly in the script however for ease of use and reuse the fol lowing built in SIMs are made available to the JiveScript by this implementor e ActiveNodeRenderer instanced when generating individuals and arte facts e BagItemRenderer model of the bag items Design and Implementation 69 e BagRenderState model of the inventory GUIState used to output notifications and to acquire user input HotSpotRenderer model of the Bag Graph HotSpots SceneRenderState model of the scene that allows to quickly setup re mote dialogues and trade transactions for the avatars in the scene e ShopCatalog used to setup trade transactions with NPCs The Shell Implementor extends the JiveScript internal engine based on the scripting API javaz script 52 and introduces its own commands but it is ac tually not much more than a textual user interface that delegates the work to its superclass Once this implementor is introduced every sort of command line MUD MOOs adventure computer games or textual simulations are ready to be produced simply by writing the appropriate JiveScript but its real purpose remains mostly that of development and debugging of new features for JIVES jME Implementor Being the objectives of this thesis focused on 3D Virtual Environments there was the need to code an Implementor that wou
123. iPortalTo2 sceneiPortalTo2 bindAction new org jives actions PortalAction scenelPortalTo2Action scenel scene2 VAR sceneiCoffer new org jives core JivesActiveNode scenelCoffer new org jives implementors engine jme NPCRenderer Models coffer coffer mesh aml new com jme3 math Vector3f 180 5 10 0 2 scenel addActiveNode sceneiCoffer scenelCoffer bindAction new org jives core JivesAction openCoffer new org jives sim JivesActionModelIntf 1 execute function jivesEvent 4 bag0 addBagItem Jives get woodenStick org jives core JivesBagItem 1 bag0 addBagIten Jives get nylonWire org jives core JivesBagItem 1 bag0 addBagIten Jives get hook org jives core JivesBagItem 2 gui notification Received a wooden stick a nylon wire and two hooks leo getDescription function return Open coffer render function jivesRenderableIntf gui notification this getDescription ID JiveScript ME Demo 173 LA Doon to scene ee _ _ c ee scene0PortalTol new org jives core JivesActiveNode scene0PortalToi new org jives implementors engine jme PortalRenderer Models portal portal mesh zml new com jme3 math Vector3f 100 6 10 DE scene0 addActiveNode scene0PortalTo1 scene0PortalTo1 bindAction new org jives actions PortalAction scene0PortalTolAction scene0 scenel 4A NPC 2 DTS ei dialogueRenderer new org jives
124. iddle button of the mouse In order to make the Combina tion System more user friendly a HotSpot Combination Helper is provided The user can directly select the desired HotSpots by clicking them and they will be automatically aligned ready to be combined The user has only to conclude the combination by using the space bar or the middle mouse button The combination will succeed only when the right HotSpots have been merged In Figure 6 34 is 114 Development and Usage represented the Combination Screen while in Figure 6 35 the result of a successful combination eo Monkey Engine 3 0 Figure 6 34 JIVES Combination Screen Trading is possible both with Non Playing Characters and Playing Characters Trading with Non Playing Characters is predefined by the JIVES developer while trading between Playing Characters is totally at discretion of the users it can consist in an exchange of items or even in a gift by a user to another one In both cases trading is activable by right clicking the character of interest and selecting the Trade action When the two traders are Playing Characters once a user has requested a trade to another user the trade request will appear to the latter one as shown in Figure 6 36 If the user who received the request accepts the trade a notification will appear to the first trader Figure 6 37 represents the moment in which the notification is received After the trade has been accepted
125. iment it has been decided to try to improve the start up performances by reducing the number of classes that the MultiInstanceEndpoint JXSE 54 class loader has to load while starting the network The start up experiment has been repeated after the implementation of that optimization leading to have different performance results The MacBookPro start up average time is 11 23 seconds with a worst time of 12 6 seconds and the best one of 10 2 seconds the iMac per forms the start up in a range from 14 0 and 21 4 seconds with an average of 15 85 the MacBook achieves an average of 17 34 seconds with a minimum of 15 8 and a maximum of 28 4 seconds the Sony Vaio starts JIVES in a best time of 15 05 and a worst time of 20 88 seconds obtaining an average value of 17 82 seconds Performance Metrics and Evaluation 131 The start up experiment has been done varying the connection type from LAN connection to Internet connection but the application is not affected in terms of boot speed the average times are similar in both cases The comparative graph depicted in Figure 7 1 visualizes the performances computed from the first exper iment with a dashed line and the performances from the second experiment with a solid line a a eS ini gt terrer Ore Qr O O Seconds lt gt MacBookPro 1 MacBookPro 2 iMac 1 iMac 2 MacBook 1 MacBook 2 Sony Vaio 1 Sony Vaio 2 Figure 7 1 Start up experiment The optimi
126. implementors engine jme nifty DialogueController Dialogue 0 sceneONPCODialogueORoot makeDialogue 41 sceneONPCODialogueORoot question Hello answer Nice to meet you actions new org jives actions StartDialogueAction scene0NPCODialogue0RootReq0Action scene0NPCODialogue0Intro dialogueRenderer dialogueRenderer makeDialogue 4 sceneONPCODialogueOIntro question Where am I answer You are in Jives basic demo actions new org jives actions StartDialogueAction Jives generateld scene0NPCODialogue0Dialogues question Who are you answer I m a non playing character I m here to demonstrate the dialogue system Ask your questions actions new org jives actions StartDialogueAction Jives generateld scene0NPCODialogue0Dialogues question Have a nice day answer Goodbye 174 JiveScript ME Demo dialogueRenderer dialogueRenderer makeDialogue 4 sceneONPCODialogueODialogues question Can you give me an item to put in inventory answer I can but for demonstration the limit has been set to two items only actions new org jives actions BagItemAction Jives generateld dialogueltem bag0 new org jives actions StartDialogueAction Jives generateld scene0NPCODialogue0Dialogues question Can I trade items from my inventory answer Yes we can trad
127. include the number of transmissions produced by the propagation mechanism of the underlying network layer pare o o 90 80 70 60 50 40 30 20 10 0 O 00 00 0 1 2 3 4 5 6 7 8 9 10 Number of nodes Before Linear Interpolation After Linear Interpolation Number of message transmissions Figure 7 3 Total number of message transmissions for number of nodes In terms of FPS frames per second the execution of the ME 31 Test Demo in a Fullscreen exclusive display mode reveals to be quite variable about performance the MacBookPro runs the Demo ranging from 23 FPS to 71 FPS on the iMac and the MacBook the FPS vary from 1 to 20 and from 3 to 9 respectively the Sony Vaio executes the jME 31 Test Demo up to 11 FPS When more than 4 5 users are connected to the same scene the performance degradation in the execution of the Demo is clearly visible only using the MacBookPro the difference was not so noticeable In Table 7 2 are specified the performances in terms of FPS obtained varying the display resolution The experiment has been performed running the jME 31 Test Demo in a shared LAN session with three participants During the execution of the tests it has happened that the application crashed in a couple of occasions in the first one the event has occurred thirty minutes after the application has been started the jME 31 Test Demo quit unexpectedly in the second case there was not a real crash but a freeze related t
128. ine game development problems with a novel network scripting language In Proceedings of the 7th ACM SIGCOMM Workshop on Network and Sys tem Support for Games New York NY USA 2008 NetGames 08 ACM pp 85 90 61 SECOND LIFE Virtual Worlds Avatars free 3D chat online meetings Second Life Official Site http secondlife com Aug 2011 62 SONY ONLINE ENTERTAINMENT EverQuest II Online Game Official Game Site http everquest2 com Sept 2011 63 STATCOUNTER StatCounter Free Invisible Web Tracker Hit Counter and Web Stats http www statcounter com Nov 2011 64 THE ECLIPSE FOUNDATION Eclipse The Eclipse Foundation Open Source community website http www eclipse org Nov 2011 65 VANI V AND MOHAN S Interactive 3D class room a framework for Web3D using J3D and JMF In Proceedings of the 1st Amrita ACM W Celebration on Women in Computing in India New York NY USA 2010 A2CWiC 10 ACM pp 24 1 24 7 66 VERNA D AND GRUMBACH A Can We Define Virtual Reality The MRIC Model In Virtual Worlds 1998 J C Heudin Ed vol 1434 of Lecture Notes in Computer Science Springer pp 29 41 67 VERSANT CORP DB4O Java amp NET Object Database Open Source Object Database Open Source Persistence OODB http www db4o com Oct 2011 68 VERSTRYNGE J The JXTA Java Standard Edition Implementation Pro grammer s Guide 2011 BIBLIOGRAPHY 191 69 WEB3D
129. ing the whole logic of the application the virtual objects their relations and behaviours JiveScript Being Java 51 based there is no problem in writing a Java 51 application that relies on JIVES compile it and execute it The proposed alternative in any case is to stick to VESLOM in coding all the necessary implementors then write the final applications directly in JiveScript The advantage of this approach is the internal management of scripted applications because it s guaranteed that every participant of a session is executing the same application and the intrinsic exploitation of the reusability of the middleware so that a lot of different working application scripts can rely on a small set of good written implementors This vision derives from the fact that learning a strict syntax interpreted language like JiveScript is much more easy than entering the low level details of the system in order to hook in the application code JiveScript is based on Sun s javaz script package 52 from the JDK This choice was preferred over Mozilla Rhino 40 not to introduce another dependency in the project and because of their built in management of security when it comes to accessing private or protected scopes while in Rhino 40 it s not impossible it s harder to achieve A trade off in this solution is that Sun s javaz script package 52 does not give the full access to native JavaScript object and where needed this access is
130. ion techniques However this aspect had been widely expected since JIVES was never meant to be spe cialized in the optimization of any particular requirement Our aim was not to compare JIVES with other existing frameworks at a technical level but was to provide something new in the Virtual Environment systems panorama this aspect was largely achieved by creating a totally Open Source product which of fers a network architecture based on a Peer To Peer technology its own scripting language and provides an important HotSpot based Item Inventory Management System JIVES can thus be considered without a doubt a success and a signifi 150 Conclusions and Future Work cant starting point in the direction of creating a Virtual Environment framework that includes all the features and the optimizations needed in the development of such applications and that may be of interest to the developer community 8 2 Future Work Even if the project already looks promising and it is overall stable there are many feature implementations and improvement possibilities many of those would probably require a partial recoding but the very basic structure of the software is not likely to change The following list propose some key point that can make the project better ordered from the one that is considered the most urgent to the least e Encryption of the local database as soon as an XTEA encryption adapter for DB40 67 will be released the mech
131. ion urlConn url openConnection Entering the Proxy username and password String password XMLConfigParser proxyUsername XMLConfigParser proxyPassword base64 encoding of the password String encoded Base64 encodeBase64String password getBytes Setting up the connection urlConn setRequestProperty Prozy Authorization encoded JXTA 54 provides a Core set of services e EndPoint Service used to send and receive messages between Peers e Resolver Service used to send generic query requests to other Peers In addition to the Core services JXTA 54 defines additional standard services 38 Design and Implementation e Discovery Service used by Peers to search for Peers resources e Membership Service used by Peers to securely establish identities and trust within a Peer Group e Access Service used to validate requests made by one Peer to another e Pipe Service used to create and manage pipe connections between the Peers e Monitoring Service used to allow one Peer to monitor other members of the same Peer Group JXSEImplementor takes possession of all the Core set of services while with respect to the Standard set of services only the Discovery Service and the Pipe Service are used in the JIVES Networking Layer Architecture With regard to the exchange of messages between Peers JXTA provides this communication through communication channels called pipes In particular JXTA
132. is system is designed with the scalability requirement in mind Several techniques are adopted such as the subdivision of the virtual world into several logical regions in order to reduce message exchange or a prediction based concur rency control implemented in order to allow real time interaction for users Inter est management and scalability requirement are faced also in the Message Oriented Middleware 39 through which the traditional interest management techniques such as the region based technique and the aura based technique are improved by a new predictive interest management scheme Move 23 and the Joint Hierarchical Nodes based User Management JoHNUM are another efforts in creating a mid dleware that is completely scalable consistent and high performance based with particular attention given respectively to data extraction and region based interest management Reducing bandwidth use and latency optimization are other design problems in the construction of a Virtual Environment Fabre 18 faced this kind 16 Related work of issues by creating a new Virtual Environment middleware based on VRML X3D and Java 51 languages The new important feature introduced by this framework is the possibility to embody in the Virtual Environment autonomous creatures called mobile agents whose behaviour is easily defined through the mid dleware Also Quax 58 addressed the use of autonomous avatars inside a Virtual Environment Through
133. ive Script as shown in Code Snippet 6 12 specifying which items the NPC has to receive in order to accomplish the trade and which items the NPC gives to the user In the proposed example the NPC will receive two coins in order to give a apple to the user Code Snippet 6 12 Trade with a NPC Bind trade to NPC tradeltem Jives get apple org jives core JivesBagItem catalog new org jives implementors engine shell ShopCatalog catalog addEntry tradeltem 1 dialogueltem 2 org jives implementors engine shell SceneRenderState setupTradeAction scene0NPCO bag0 catalog The whole JiveScript Shell Demo and JiveScript jME 31 Demo are reported in Appendices B and C Chapter 7 Performance Metrics and Evaluation 7 1 Performance Metrics The performance metrics discussed in this section are both quantitative and qual itative In order to evaluate the quantitative performance metrics an experiment based on the execution of the ME 31 Test Demo has been set up using different hardware machines The hardwares involved are a MacBookPro 2 3 GHz Intel quadCore i7 with 8 GB 1333 MHz DDR3 and Graphics Card AMD Radeon HD 6750M 1024 MB an iMac 2 66 GHz Intel dualCore 2 Duo with 4 GB 800 MHz DDR2 SDRAM and Graphics Card ATI Radeon HD 2600 Pro 256 MB a Mac Book 2 26 GHz Intel dualCore 2 Duo with 2 GB 1067 MHz DDR3 and Graphics Card Nvidia Geforce 9400M 256 MB and a Sony Vaio 2 10 GHz Intel dualCore 2 Duo with 4
134. iveNode scene2Pond scene2Pond bindAction new org jives actions ActivateNodeWithItemAction useFishingRodAction bag0 scene2Pond new org jives sim JivesActionModelIntf 1 execute function jivesEvent 4 action jivesEvent getAction if action getBag getSelectedItems size 1 gui notification Select exactly one item from bag ae Wine proeect Dg else selectedItem action getBag getSelectedItems get 0 getId if selectedItem equals fishingRod gui notification Fishing else gui notification selectedItem doesn t work here getDescription function return Fish 172 JiveScript ME Demo render function jivesRenderableIntf gui notification this getDescription it DOOR BO Sesma 2 2 20 2 22 220 SSS Ses 2299209222 SS SS SRS SSS aS sceneiPortalToO new org jives core JivesActiveNode sceneiPortalTo0 new org jives implementors engine jme PortalRenderer Models portal portal mesh aml new com jme3 math Vector3f 170 6 90 DIE scenei addActiveNode scenetPortalTo0 sceneiPortalTo0 bindAction new org jives actions PortalAction scenelPortalTo0Action scenel scene0 WARD A Sa i scenelPortalTo2 new org jives core JivesActiveNode sceneiPortalTo2 new org jives implementors engine jme PortalRenderer Models portal portal mesh aml new com jme3 math Vector3f 160 6 50 DE scenel addActiveNode scene
135. ively Multi player Online Games although this could still be done The Virtual World model adopted by JIVES follows the one proposed by Men chaca 36 The Virtual Worlds that can be created by using our framework are composed by three main elements Individuals Artefacts and Decorations Men chaca 36 defines the Individuals as users avatars that interact within the Virtual World JIVES allows the developer to define the actions that users are able to perform within the Virtual Environment Artefacts are elements Individuals can interact with while Decorations are static objects or animated with determin istic time or event based behaviour that are visible within the Virtual World but do not have collaboration interfaces as Menchaca 36 explains in his study Unlike projects mentioned before which face specific Virtual Environment design issues JIVES wants to be as simple and general as possible allowing the devel oper to build a new Virtual World in a fast and simple way In order to meet this requirement JIVES provides its own scripting language called JiveScript JiveScript is a structured scripted Java 51 language based on the scripting API javax script 52 package available in the Java SE 6 platform Through JiveScript the developer can create efficiently a new 3D Virtual Environment specifying the whole logic of the application the virtual objects and their behaviours Being JiveScript a structured language the developer
136. ives implementors engine jme PlayingCharacterRenderer setModelPath Models 0to 0to mesh axml scene0Model new org jives implementors engine jme SceneRenderState new org jives sim SceneModelIntf destroy function activate function onActiveNodeAdd function jivesActiveNode if jivesActiveNode getModelType equals org jives network RemoteActiveNode org jives implementors engine jme SceneRenderState setupRemoteDialogue jivesActiveNode org jives implementors engine jme SceneRenderState setupTradeAction jivesActiveNode bag0 onActiveNodeRemove function jivesActiveNodeArray H scene0 new org jives core JivesScene Scene 0 scene0Model sceneiModel new org jives implementors engine jme SceneRenderState new org jives sim SceneModelIntf destroy function activate function onActiveNodeAdd function jivesActiveNode if jivesActiveNode getModelType equals org jives network 168 JiveScript ME Demo RemoteActiveNode org jives implementors engine jme SceneRenderState setupRemoteDialogue jivesActiveNode org jives implementors engine jme SceneRenderState setupTradeAction jivesActiveNode bag0 onActiveNodeRemove function jivesActiveNodeArray H scenei new org jives core JivesScene Scene 1 sceneiModel scene2Model new org jives implementors engine jme SceneRenderState new org jives sim SceneModelIntf destroy
137. jME 31 Demo the only differences are that for each HotSpot are defined in space using 3D coordinates for positioning and a radius for sensi bility and the item model refers to the mesh through which the item is visualized in a 3D Virtual Environment Code Snippet 6 9 shows how the items are defined in the jME 31 Demo script Development and Usage 125 Code Snippet 6 9 ME Items combinations S Define bag0 bagO makeBag 4 bag0 id woodenStick categories found combines new org jives implementors engine jme HotspotRenderer com jne3 math Vector3f 3 42 3 08 0 19 1 Yo sula l new org jives implementors engine jme HotspotRenderer com jme3 math Vector3f 9 5 7 8 0 03 1 stickWithWire l model new org jives implementors engine jme BagItemRenderer Models woodenStick woodenStick mesh zml 0 05 A strong and flexible wooden stick commonActionsRenderer gui id nylonWire categories found combines new org jives implementors engine jme HotspotRenderer com jne3 math Vector3f 10 29 1 0 91 1 stickWithWire l new org jives implementors engine jme HotspotRenderer com jme3 math Vector3f 2 54 1 25 6 24 2 4 null l model new org jives implementors engine jme BagItemRenderer Models nylonWire nylonWire mesh zml 0 016 A piece of nylon wire commonActionsRenderer gui bagModel bagCombiner E
138. just to start JIVES and load the right JiveScript In order to correctly load the script the file must have the jives extension Once the user has started JIVES in a console environment some commands are available to perform specific operations These commands can be shown by typing in the console the command help As shown in Figure 6 14 the command help let the user see two kinds of commands the first ones are specifically related to the Shell Implementor and 94 Development and Usage JIVES v 1 0 0 JiveScript v 0 2 Shell ore 123 MB memory 66 MB free This script name is script MTMxOTI4NjQ30DE20A Ready help Implementor commands exit reset creen and memory help clearScreen move activate lookAround JiveScript commands name load me reset emory help version echo echo ut line break eval memstats __scripting __name __uses entities implode saveState loadState makeBag makeDialogue Ready Terminate the execution of the environment and exit Revert the system to the initial state cleaning up s Display this help Clear the console screen Move to a point in the scene Activate an activable object of the scene Print a list of surrounding active nodes Display the script name Load and executes a JiveScript file Reference to your alter ego Revert the system to the initial state cleaning up m Display this help Di
139. lability in a cost effective manner In order to reduce the amount of message traffic several techniques have been proposed such as the subdivision of the virtual world into portions commonly known as Area of Interest AOT allowing the user to interact Related work 19 only with entities within his AOI or the Delaunay Triangulation 8 a technique for dramatically decreasing maintenance overhead by reducing the number of con nection changes due to users insertion and movement Recently Virtual Environment systems were affected by the growing interest in the use of scripting languages Powerful scripting languages improve applica tion performance while making the development more efficient 72 60 These languages allow developers to easily specify how an object or character is sup posed to behave without worrying about how to integrate this behaviour into the application itself User created content is another reason for Virtual Environment applications to support scripting Virtual Worlds such as Second Life 61 have made player scripting a common topic of conversation Besides scripting allow players to modify application behaviour without having access to the code base They provide a sandbox that unlike a traditional programming language limits the types of behaviour the player can introduce Our aim is to provide a new Java based Multi user Modular Networked Vir tual Environment framework the Java Interactive Vir
140. ld allow the graphical representation of JIVES entities The MonkeyEngine 31 turned out to be a good product to easily integrate JIVES with There are two main issues to deal with when introducing this kind of imple mentation of the Presentation Layer The first is the actual rendering of geometry the second the need to display and operate a Graphical User Interface GUI ME 31 can resolve both issues within itself offering a scene graph approach to ren der geometry and an internal integration with Nifty GUI 43 The work that needed to be done was translating the Shell Implementor models into their ME 31 equivalent thus many of the available SIMs share at least the name The complete list is the following 70 Design and Implementation BagCombinerState state enabled when the user has to combine different items interactively if they define a combination that requires HotSpots The items can be rotated using the left mouse button translated with the right mouse button and an attempt to combine them is realized pressing the middle mouse button or the space bar The combination item is obtained if the right HotSpots get close enough For demonstration HotSpots are represented by blue transparent spheres but of course can be implicit BagItemRenderer model of the bag items BagRenderState model of the inventory GUIState used to encapsulate Nifty 43 interface and common GUI re lated operations like notification
141. leIntf gui notification this getDescription Udi DOOR BO HETO SoSeso n scene0PortalToi new org jives core JivesActiveNode scene0PortalToi new org jives implementors engine shell ActiveNodeRenderer org jives implementors engine shell ActiveNodeRenderer TYPE_PORTAL Portal to Scene 1 DE scene0 addActiveNode scene0PortalTo1 scene0PortalToi bindAction new org jives actions PortalAction scene0PortalTolAction scene0 scenel NPC Dialogue 0 sceneONPCODialogueORoot makeDialogue 4 JiveScript Shell Demo 165 sceneONPCODialogueORoot question Hello answer Nice to meet you actions new org jives actions StartDialogueAction scene0NPCODialogue0RootReq0Action scene0NPCODialogue0Intro dialogueModel gui makeDialogue 4 sceneONPCODialogueOIntro al question Where am I answer You are in Jives basic demo actions new org jives actions StartDialogueAction Jives generateld scene0NPCODialogue0Dialogues question Who are you answer I m a non playing character I m here to demonstrate the dialogue system Ask your questions actions new org jives actions StartDialogueAction Jives generateld scene0NPCODialogue0Dialogues question Have a nice day answer Goodbye dialogueModel gui makeDialogue 4 scen
142. ll in order to be performed with ease the user has only to se lect by clicking them the proper HotSpots and complete the combination The combination system has been implemented with a HotSpot combination helper in order to make it more user friendly the goal has been largely achieved Even when the users were forced to perform the combination without assistance of the combination helper although with some difficulties the task has been completed It is important to remark that the choice to use a combination helper is strictly related to the design of the Presentation Implementor The decision of a Peer To Peer architecture as the basis of the JIVES Network ing Layer can be considered an innovative choice due to the fact that the most 144 Performance Metrics and Evaluation of the existing Virtual Environment frameworks implement the network function alities using a Client Server technology Thanks to the Peer To Peer technology integrated in the JIVES framework a developer can create new Virtual Environ ment applications running on Internet at no server costs Despite some difficulties in implementing the Network Implementor using the JXTA 54 Peer To Peer ar chitecture we can be satisfied due to the proper functioning of the JIVES network both when using a LAN connection and an Internet connection The choice of adopting the Java 51 language has proved to be the right one the Java 51 compiler generates Java Virtual Machin
143. locally on the same hardware machine without having the possibility to run JIVES in a LAN or in the Internet any traffic that a JIVES application sends to the loopback interface is immediately received on the same interface The user has to change the netInterface field by specifying the name of the interface through which it is possible to use a work ing connection For example if the enabled working inteface is called en1 the netinterface field has to be set in that way lt netInterface gt en1 lt netInterface gt In order to discover which is the working interface running on the user s com puter it is sufficient to run the command ifconfig in a terminal under a Linux or MAC OS X Environment or the command ipconfig if the OS is Windows based These commands will show to the user all the network interfaces available on his computer the right one is the interface which is correctly connected to a LAN network or Internet and to which the router has assigned a valid IPv4 or IPv6 All the fields belonging to the server tag are related to the server in which is hosted the directory of Rendezvous These fields are useful only if the user wants to execute the JIVES application using an Internet connection In order to show the proper functioning of the Demo using an Internet connection a Ren Development and Usage 93 dezvous directory is hosted on the Sourceforge 24 JIVES web space Obviously the developer has to provide the co
144. ly working both in a LAN network and a Internet network The JIVES user has the possibility to choose this modality by correctly set up the JIVES Network Settings Both in the LAN modality and the INTERNET modality the network has to be started by a Rendezvous Relay In the LAN modality Peers who want to connect to the network have to know the external IP of the Ren dezvous Relay and insert it into the JIVES network settings Differently in the Internet modality Peers do not have the possibility to know in advance the ex ternal IP of the Rendezvous Relay connected at the time In order to overcome this issue JIVES provides a mechanism whereby any Rendezvous relay running a JIVES application is registered in a Rendezvous directory hosted by a dedicated server A Rendezvous directory sample is fully reported in Appendix D The default server adopted by JIVES is provided by sourceforge net 24 but the developer is encouraged to use any other hosting server just specifying the URL in the JIVES network settings Associated to each Rendezvous Relay registered on the server there is a Token composed by the Peer ID of the Rendezvous Relay and the name of the JIVES application currently running Through the use of the Token JIVES ensures that only the legitimate Rendezvous Relay is able to perform writing operations on the Rendezvous directory such as updating the in formation status or unsubscribing from the list Obviously the writing operations on
145. mechanisms The event driven architecture 37 is described further on in section 5 2 1 5 1 3 TradeItemsAction Protocol This paragraph explains in detail one of the possible actions designed to be per formed in the environment Specifically the trade action allows to exchange items between inventories and has transactional behaviour the whole operation has to be either committed on both sides or rolled back on both sides eventually com pensating the temporary changes that has been introduced on the inventories Even though trading is not the only possible transaction to be defined in the JIVES Environment it s provided by default among with some other basic actions thus its practical study is presented here as a sequence diagram in Figure 5 3 The steps before transaction goes into INIT_AND_DEST_CONFIRMED are handshaking steps and allow both users to select which items to give from their bag and to see which item will be received from the counterpart Note that each time a transaction is dispatched by the NetworkDispatcher class the local copy of the same transaction is merged with the remote one so that its internal state can be synchronized When the transaction goes in INIT_AND_DEST_CONFIRMED state on the two peers symmetrically the commit is performed and a roll back thread starts The roll back thread has a time out of ten seconds at the end of which the transaction is aborted and the previous commit is compensated During
146. ment Sys tem Official Web Site http sourceforge net projects jives Sept 2011 DE OLIVEIRA J C AHMED D T AND SHIRMOHAMMADI S Perfor mance enhancement in mmogs using entity types In Proceedings of the 11th IEEE International Symposium on Distributed Simulation and Real Time Applications Washington DC USA 2007 DS RT 07 IEEE Computer Society pp 25 30 FABRE Y A framework for mobile agents embodied in X3D networked virtual environment In Proceedings of the eighth international conference on 3D Web technology New York NY USA 2003 Web3D 03 ACM pp 113 122 FALKO BRAEUTIGAM Ozone Java OODBMS http sourceforge net projects ozone Oct 2011 FAN L TAYLOR H AND TRINDER P Mediator a design framework for P2P MMOGs In Proceedings of the 6th ACM SIGCOMM workshop on Network and system support for games New York NY USA 2007 NetGames 07 ACM pp 43 48 FREE SOFTWARE FOUNDATION Bash GNU Project http www gnu org software bash Nov 2011 FREE SOFTWARE FOUNDATION Welcome to GPLv3 GPLv3 http gplv3 fsf org Sept 2011 186 BIBLIOGRAPHY 23 Garc a P MONTALA O PAIROT C RALLO R AND SKARMETA A G MOVE component groupware foundations for collaborative virtual environments In Proceedings of the 4th international conference on Collab orative virtual environments New York NY USA 2002 CVE 02 ACM pp 55 62 24 GEEKNET INC SourceFo
147. n Active Node using a Bagltem adding and removing items from the inventory traversing por tals starting dialogues and trading items The TradeltemsAction is not the same Design and Implementation 59 as the other actions because exchanging objects between different peers on the network implies the concept of transaction which is supported at a very low level because of the high abstraction every transaction simply implements the TransactionIntf interface which is just a guideline however e Atomicity can be guaranteed by a timed out roll back if commit is not confirmed by both parties e Consistency is assured for every transaction the distributed state of the application remains consistent as long that each and every Bag Item traded from one peer to another is respectively given from the former and received by the latter e Isolation is enforced by mean of an EventListener to prevent other JIVES Actions to occur on the requested activable while the transaction is going on e Durability is guaranteed in the moment that the registry is persisted which is a good idea after an important transaction occurred Dialogues Manager JIVES dialogues can be divided in two categories Playing Characters PC dia logues which are chat like interactions between the avatars of human users and Non Playing Characters NPC dialogues that allows an human user to acquire informations from the environment in a multiple choice in
148. n of the entire project and we discuss possible future develop ment directions JIVES aims at being a trade off solution to a complex problem completely Open Source having an experimental design being extensible flexible and reusable it can be considered a good research result in the world of Virtual Environment frameworks Estratto Questa tesi presenta il design e l implementazione del Java Interactive Vir tual Environment System JIVES framework un sistema multi utente modulare basato su Java che offre funzionalita di rete attraverso il quale si possono realiz zare applicazioni per web e desktop L intera architettura suddivisa in tre livelli principali ordinati come segue il Core implementa le caratteristiche astratte co munemente ritenute essenziali nella creazione di ambienti virtuali il livello degli Implementors consiste in moduli che contribuiscono alla realizzazione di tali carat teristiche il livello applicativo definisce il proprio linguaggio di script in maniera tale che il programmatore rimanga completamente estraneo ai dettagli implemen tativi dei livelli inferiori Allo stato attuale JIVES offre un modulo di rete basato su architettura Peer To Peer ed un motore di visualizzazione 3D assieme ad essi viene fornito lo script di un applicazione dimostrativa Un sistema innovativo di gestione dell inventario basato su HotSpots integra una modalit significativa per combinare oggetti dell inventario e permette
149. nction jivesRenderableIntf object Output Application Tasks Rhinc newJiveScriptTemplate jives press successfully Figure 6 7 JiveScript Editor Netbeans plugin Checkout from CVS Enter Repository Location Information CVS Define the location and protocol required to connect withan existing CVS repository Location Host jives cvs sourceforge net Repository path cvsroot jives v Authentication User anonymous v Password Connection gt Connection type pserver 8 Use default port O Use port C Save password could trigger secure storage login To manage your password please see Secure Storage Configure connection preferences lt Back Next gt Cancel Finish Figure 6 8 Configuring the CVS connection in Eclipse 82 Development and Usage Build guide for MonkeyEngine SDK Netbeans 1 From the Team Menu select CVS then Checkout 2 Specify the following connection string pserver anonymousQjives cvs sourceforge net cusroot jives 3 In the Module to Checkout section write jives then click Finish to import the project into the workspace Build targets Once the project is setup in your favourite IDE you can use the predefined build targets to generate the different parts of the JIVES project Those are e clean cleans the output direc
150. ngine shell BagItemRenderer A coin received talking to that strange guy commonActionsRenderer gui id woodenStick categories found combines new org jives implementors engine shell HotspotRenderer bottom null new org jives implementors engine shell JiveScript Shell Demo 161 HotspotRenderer tip stickWithWire l model new org jives implementors engine shell BagItemRenderer A strong and flexible wooden stick commonActionsRenderer gui id nylonWire categories found combines new org jives implementors engine shell HotspotRenderer edge stickWithWire new org jives implementors engine shell HotspotRenderer middle null l model new org jives implementors engine shell BagItemRenderer A piece of nylon wire commonActionsRenderer gui id hook categories found combines new org jives implementors engine shell HotspotRenderer eye fishingRod new org jives implementors engine shell HotspotRenderer hook null l model new org jives implementors engine shell BagItemRenderer A metal hook commonActionsRenderer gui id stickWithWire categories found combines new org jives implementors engine shell HotspotRenderer wireEdge fishingRod l model new org jives implementors engine shell BagItemRenderer A nylon wire tied to a wooden stick c
151. nheriting the Activable abstract class like JivesActiveNode JivesBag and JivesBagltem classes do Transactions are very generic because they are defined by an interface the TransactionIntf as also the Implementors are respectively defined by EnginelmplementorIntf and NetworkImplementorIntf Events and Event Listeners are JivesObjectIntf too Implementing the EventListenerIntf the handleEvent method is served with every JivesEvent processed Network receive events are handled this way by NetworkSender Receiver class Representations of remote entities implement this class to send and receive messages like RemoteActiveNode does Messages are specified by the NetworkMessage class It has a sender address realized by the NetworkAddress class and a payload which can be any serializable entity like an HashMap or maybe a dialogue containing one RemoteDialogueRequest Other rel evant packages are org jives jivescript which includes the JiveScript interpreter org jives bg that contains the Bag Graph JIVES dialogue classes are restrained in org jives dialogues while SIMs are contained in org jives sim and implemented by the respective JIVES Core class that delegates to them 156 JIVES Class Diagram getFILENAME getinternalEngine getliVESCRIPT_VERSIONI getmosl helpl Implodel istoadingl load loadstate mel memstats namel setContext setinternalEngine version 0
152. nnection Rendezvous connection Hostthe session Ri Advanced network settings Netinterface loo ld Use proxy 100 P Frames per second 59 Figure 6 22 Network Settings Graphical User Interface 104 Development and Usage same LAN network by deselecting the Host the session box and specifying the JP Address and Port fields with the IPv4 and the port of the Rendezvous to which he wants to connect It is also possible to check the Use Pv6 box in order to use an IPv6 connection Note that JIVES offers the IPv6 connection as an experimental feature In the case the Use IPv6 box is selected obviously the user has to fill the IP Address field with the IPv6 address of the Rendezvous to which he wants to connect In the case the user chooses the Internet connection to run the JIVES application all the parameters included in the Rendezvous connection tab are not modifiable any more because it is JIVES itself to check the Rendezvous directory on the server and decide to start the user as a Rendezvous or a simple Peer The user has to specify the working network interface by selecting it in the Net interface list all the network interfaces of the machine on which JIVES is running are listed the user has only to select the right one Advanced features are represented by the Rendezvous Directory URL and the Account confirmation URL fields the first one is related to the URL in which is stored the Rendezvous directory the
153. notation Those methods will be parsed when the engine context is created and will be put available in JiveScript global scope as commands The following list presents the commands introduced until JiveScript v 0 2 e name display the current script name set by the __name directive e load load a JiveScript application start the network and register this peer in the rendezvous directory 1 Parameter path the path to the local resource e me returns a reference to the representation of self as a JivesActiveNode e reset reverts the system to the initial state cleaning up memory e echo prints the textual representation of any object 1 Parameter object the object to print 2 Parameter keepLine Optional true to avoid line break Defaults to false e eval evaluates a JiveScript The result of the evaluation are put in the current scope so writing a 2 for instance equals writing eval a DI 1 Parameter script the script to evaluate Design and Implementation 43 e memstats prints the current state of memory usage and availability e entities outputs the list of the contents of the JIVES registry e version displays JiveScript version e implode returns a JavaScript array of the Java objects passed as pa rameters This is useful because there is no direct cast from a Java array to a JavaScript array 1 Parameter params Vararg the Java objects to implode in an ar
154. nterface The CVE VM system is developed according to the Client Server model in which the Server is responsible for managing the communication among the users and maintaining the consistency of the database allowing the clients to use a browser to navigate and manipulate objects in the Virtual World Specific efforts 57 have been made in order to define several collaborative manipulation techniques through which multiple users simultaneously can manipulate an ob ject in a Virtual Environment CVEs have been created also for Data Knowledge Extraction this is the case of the LiveNet system 4 developed at the University of Technology Sidney Virtual collaboration systems do not provide any support for data collection aimed at knowledge discovery while the LiveNet 4 framework embeds knowledge discovery by applying data mining algorithms through which 1t is possible to discover useful patterns in the data An other important aspect of the Virtual Environment middlewares is the choice of the network architecture Most of the professional Virtual Environment tools adopt the Client Server architecture while recently Peer To Peer architec ture was taken in consideration by more and more projects 35 20 10 or even hybrid architectures 35 In Peer To Peer based Networked Virtual Environments system and data management is distributed among all the participating users By sharing users resources Peer To Peer architectures achieve high sca
155. nterface which would allow the developer to choose which JIVES object to instantiate and parametrize while the underlying code is procedurally generated Native resolution of JavaScript objects using the javaz script API allows to avoid taking care of security issues like accessing protected Java scopes in Javascript but given that it does not expose JavaScript objects this implies that native objects access has to be obtained using the Reflection Conclusions and Future Work 153 API In the remote hypothesis that the low level of the scripting API will change there is going to be some small recoding to be done e Android support officially confirmed the stable release of the ME3 31 will support Android development At the moment the beta version of the SDK includes already the possibility to deploy an Android application This feature can be exploited to extend the support of the JIVES framework also to Android by creating a new Presentation Implementor that gives the possibility to run a JIVES application on a mobile device Appendix A JIVES Class Diagram Figure A 1 is the UML diagram of the most important classes inheritance show ing public methods only Core classes inherit the JivesObjectIntf interface al lowing them to exploit the JIVES registry Jives class is static and does not need any instance All actions extend JivesAction class as RemoteJivesAction class does The hierarchy of activables is defined i
156. ntinuum La al 1 5 1 Virtual Environment System Layered Object Model 27 5 2 Bag Graph Example sy ue is AAA EA 31 5 3 TradeltemsActi n Commit ooo a ad 34 5 4 JIVES Networking Layer Architecture JXSElmplementor 36 5 5 TradeItemsAction rollback Le ls dde ete A 48 5 6 Rotation step of the combination helper algorithm 51 5 7 Translation step of the combination helper algorithm 52 5 8 JIVES Component Diagram 4 e as dele Bw he Se owe he ok BOR 53 6 1 JIVES Project Folder using Eclipse 76 6 2 Adding JIVES Dependencies in Eclipse TT 6 3 JIVES Project Folder using jME SDK 78 6 4 Adding JIVES Dependencies injME SDK 78 6 5 Installing JavaScript Rhino Content Assist 79 6 6 Creating a new JiveScript o 80 6 7 JiveScript Editor Netbeans plugin 81 6 8 Configuring the CVS connection in Eclipse 81 6 9 Executing the JivesApplet 00 85 6 10 JIVES Folder Disposal ooa a a 87 6 11 Starting JIVES from Mac OS X Terminal 463 88 6 12 Shell Implementor Starting Screen 89 VI LIST OF FIGURES 6 13 Starting JIVES from Windows Command Prompt 90 6 14 List of Shell Implementor and JiveScript Commands 94 6 15 JiveScript Shell Demo Starting Scene 96 6 16 A New Entry in the Scene a 96 6 17 Moving aroun
157. o the visualization 138 Performance Metrics and Evaluation Table 7 2 Performance comparison Fullscreen 1680x1050 32bpp Windowed 1024x768 24bpp Windowed 640x480 24bpp Fullscreen 1680x1050 32bpp Windowed 1024x768 24bpp Windowed 640x480 24bpp Fullscreen 1280x800 32bpp Windowed 1024x768 24bpp Windowed 640x480 24bpp Fullscreen 1280x800 24bpp Windowed 1024x768 24bpp Windowed 640x480 24bpp Performance Metrics and Evaluation 139 of the 3D Environment through the Monkey Engine it has not been possible to restore the proper functioning of the application Alongside the quantitative performances also qualitative performances were deduced by involving two third party users The first user can be considered a medium expert user 27 years old he is not new to use a shell to run com mands is familiar with Windows and some Linux distributions knows how to juggle between the different settings of an OS has basic knowledge about Java programming The second user can be targeted as a newbie 26 years old he only knows the Windows Operating System is unfamiliar with the command line knows absolutely nothing in terms of programming The two users were subjected to the same experiment the testShell jar and the testJME jar the JiveScript Shell Demo and the JiveScript ME 31 Demo the User s Manual 6 2 and the Devel oper s Manual 6 1 have been provided
158. obtained through the Java Reflection API The JiveScript indeed can act in a sandbox mode where there is no restriction Design and Implementation 73 on input commands and it s possible to exploit all the power of the scripting lan guage to create and modify JIVES objects and interact with them This behaviour can be inhibited by the __scripting directive A comfortable way to write JiveScript code is by mean of the NetBeans Jive Script plugin 15 It features the same rapid writing features of the JiveScript Shell but it s fully integrated with the NetBeans 56 IDE it provides a textual editor for jives files assuming that the project classpath is appropriately con figured with the JIVES library and all the necessary Implementors Chapter 6 Development and Usage 6 1 Developer s Manual JIVES is Open Source software Anyone could branch it or contribute to the baseline as long as all the changes made are subject to the GNU General Public License 3 0 GPLv3 22 The JIVES development server is sourceforge net There is no need to be registered users to download or browse the code and the binaries while if you wish to contribute to the baseline you are encouraged to contact the JIVES project developers on sourceforge net 6 1 1 Development using JIVES Every release made publicly available for download is situated at http sourceforge net projects jives files From this location it will be possible to downlo
159. ommonActionsRenderer gui sb id fishingRod categories fishing combines model new org jives implementors engine shell BagItemRenderer A hand crafted fishing rod commonActionsRenderer gui bagModel bagModel Define actions bag0 bindCommonActions gui dialogueltem Jives get coin org jives core JivesBagltem Define scene models scene2Model new org jives implementors engine shell SceneRenderState 162 JiveScript Shell Demo new org jives sim SceneModelIntf destroy function activate function echo n nSCENE 2 n This room has a quiet pond with crystal ae Umane We onActiveNodeAdd function jivesActiveNode if jivesActiveNode getModelType equals org jives network RemoteActiveNode org jives implementors engine shell SceneRenderState setupTradeAction jivesActiveNode bag0 org jives implementors engine shell SceneRenderState setupRemoteDialogue jivesActiveNode onActiveNodeRemove function jivesActiveNode scene2 new org jives core JivesScene Scene 2 scene2Model sceneiModel new org jives implementors engine shell SceneRenderState new org jives sim SceneModelIntf destroy function activate function echo n nSCENE 1 n This room has a door and there s a coffer in the middle We onActiveNodeAdd function jivesActiveNode if jivesActiveNode getModelType equals org jives net
160. on useltemOnActivable inventory activable new org jives sim JivesActionModelIntf execute function jivesEvent 4 Do something getDescription function return Use item on activable render function jivesRenderablelntf 4 Li Render the action Regardless of the actual code meaning in the above code it s possible to see that the application assign a new action to an activable entity This action is par tially implemented by default in the system because activating an entity using an item is something you would expect to find in a Virtual Environment definition language But then there is something that the system doesn t know the con tent of the execute function that actually performs the activation job which is very clear instead to the writer of the application logic Functions like this one are methods of inline instanced interfaces called Structured Interactivity Models SIMs 42 Design and Implementation Commands As mentioned before JiveScript is scripted Java 51 Which in turn means that it has the complete grammar and semantic of JavaScript extended to instantiate and access Java 51 classes As an addition it defines a few simple commands to help the development of JiveScript application anyone could extend this set of commands simply by inheriting the JiveScriptEngine class and creating new static methods in its subclass marking them with the JiveScriptCommand an
161. onActionsRenderer gui id woodenStick categories found combines new org jives implementors engine jme HotspotRenderer com jme3 math Vector3f 3 42 3 08 0 19 1 null l new org jives implementors engine jme HotspotRenderer com jme3 math Vector3f 9 5 7 8 0 03 1 170 JiveScript ME Demo stickWithWire l model new org jives implementors engine jme BagItemRenderer Models woodenStick woodenStick mesh xml 0 05 A strong and flexible wooden stick commonActionsRenderer gui id nylonWire categories found combines new org jives implementors engine jme HotspotRenderer com jne3 math Vector3f 10 29 1 0 91 1 stickWithWire l new org jives implementors engine jme HotspotRenderer com jme3 math Vector3f 2 54 1 25 6 24 2 a RUEL J 1 model new org jives implementors engine jme BagItemRenderer Models nylonWire nylonWire mesh zml 0 016 A piece of nylon wire commonActionsRenderer gui id hook categories found combines new org jives implementors engine jme HotspotRenderer com jne3 math Vector3f 1 8 0 5 1 6 1 fishingRod 1 ll new org jives implementors engine jme HotspotRenderer com jme3 math Vector3f 0 5 0 5 0 0 5 y owl l model new org jives implementors engine jme BagItemRenderer Models hook hook mesh zml 0 05 A metal hook commonActionsRen
162. ook x2 coin x2 p nylonWire x1 Frames per second 52 Figure 6 32 JIVES Item Inventory Graphical User Interface If two items are selected JIVES offers the possibility to combine them in an original and significant way each item has been previously defined by the devel oper of the JIVES application as an item characterized by the presence of one or more HotSpots key points through which the item is available to be combined The possible combinations of the ME 31 Demo have been defined in the Jive Script ME 31 Demo In order to access the Combination Screen the user has to select two items by right clicking them and choosing the Select action JIVES Development and Usage 113 will ask the user in which quantity he wants to select the item by showing a slider menu The selected items are shown in the left bottom corner of the window as depicted in Figure 6 33 800 jMonkey Engine 3 0 Combine TT woodenStick x0 hook x2 coin x2 e nylonWire x0 Figure 6 33 Selecting the Items from the Inventory Once the user has selected the items he wants to combine the combination can be started by clicking the Combine button at the top of the window The Combination Screen will appear the user can rotate and translate each item and try to combine the items by joining their HotSpots When two HotSpots are correctly aligned the user can accost them by using the space bar button of the keyboard or the m
163. ork without restarting the virtual machine JXSEImplementor uses JXSE 2 6 54 the stable version at the time of its writing so it had a huge problem in dealing with JIVES reset and restart dynamics because only a single instance of a World Peer Group could be instantiated at a single time in the same JVM The solution was hiding each peer behind its own multi instance endpoint class loader so that in the same virtual machine they all had the opportunity to make a fresh start Of course dead Peers must be subject to de initialization and garbage collection appro priately while running Peers cannot have their method invoked directly because they reside in different class loaders but the multi instance endpoint deals with the issue using Java Reflection API to communicate The class loader implements a static cache so all the classes are loaded once the first time a peer is initialized Design and Implementation 53 then every time a new peer starts they are all immediately available from memory 5 2 Implementation The implementation of the JIVES framework is accurately described in the fol lowing sections by following the order dictated by the VESLOM Design Firstly the Universal Platform and all its components secondly the Networking layer thirdly the Middleware layer and finally the Application layer are explained and analysed in their implementation x x x x x 1 x n s 1 E
164. ort ports gt item 0 gt nodeValue PIDS rendezvous gt getElementsByTagName pid PID PIDS gt item 0 gt nodeValue times rendezvous gt getElementsByTagName time time times gt item 0 gt nodeValue echo IPv4 IPv6 port PID program MD5 time r n echo lt br oa break case add if strcemp _GET token md5 _GET pid _GET program 0 doc new DOMDocument doc gt preserveWhiteSpace false doc gt load rendezvous xml doc gt formatOutput true root doc gt documentElement rendezvous_list root gt getElementsByTagName rendezvous rendezvous doc gt createElement rendezvous root gt appendChild rendezvous program doc gt createAttribute program rendezvous gt appendChild program Server side Rendezvous directory active page programValue doc gt createTextNode _GET program program gt appendChild programValue MD5 doc gt createAttribute md5 rendezvous gt appendChild MD5 MD5Value doc gt createTextNode _GET md5 MD5 gt appendChild MD5Value IPv4 doc gt createElement ipv4 text_IPv4 doc gt createTextNode _GET addr IPv4 gt appendChild text_IPv4 rendezvous gt appendChild IPv4 IPv6 doc gt createElement ipv6 text_IPv6 doc gt createTextNode _GET addr2 IPv6 gt
165. pecify the path using the double backslash expression with respect to the previous example in a Windows environment the load command becomes load file C Usera user Desktop basic demo shell jives Once the script has been loaded the terminal shows a screen as in Figure 6 15 The user is located in the starting scene Using the lookAround command it is possible to see the elements presents in the scene the Non Playing Characters NPCs the Playing Characters PCs and the Artifacts such as Portals that permit to move from a scene to the next one or vice versa In Figure 6 15 there is only the player called JivesUser in the scene but if an other user runs the same JIVES application it is possible to see the new entry by retyping the lookAround command as shown in Figure 6 16 From the point of view of the second user in order to connect to the same JIVES Virtual Environment application that the first user is running it is neces sary to perform the usual operations needed to launch a JIVES application In particular the script has to be exactly the same that the first user is running while the network configuration is different If the JIVES Virtual Environment application works on a LAN connection the second user has to specify in the Development and Usage JIVES v 1 0 0 JiveScript v 0 2 Shell 123 MB memory 68 MB free This script name is JivesBasicDemo Welcome to Jives Basic Demo Thi
166. platform Library fil states Documents Documents E DS_Store networkConfiguration xml networkCon i Desktop se default xml Documents Store filezilla I Music fontconfig Figure 6 10 JIVES Folder Disposal Although JIVES creates the jives Roamingljives folder and its sub folders automatically it is still acceptable that the user creates them manually and inserts in the right location the network settings configuration files Differ ently from Windows in which the Roaming jives folder is visible the jives directory created in MAC OS X and Linux systems is a hidden folder In order to access the hidden files and directories in a MAC OS X Environment the user has to open a terminal and launch the command defaults write com apple finder Ap pleShowAllFiles bool true then restarting the Finder by executing the command killall finder while in a Linux system it depends on the specific distribution 6 2 1 Shell User s Manual A pre compiled JIVES application is composed by a single jar file the archive file format typically used to aggregate many Java class files and associated metadata and resources into one file to distribute application software or libraries on the Java 51 platform Each JIVES application built by using the Shell Implementor runs over a terminal a shell or a console Under a MAC OS X operating system 88 Development and Usage the terminal is acc
167. proxyPassword gt lt user gt lt server gt lt urlHost gt http jives sourceforge net rendezvous lt urlHost gt lt urlSecretKey gt http jives sourceforge net access getSecretKey php lt urlSecretKey gt lt httpsUsername gt lt httpsUsername gt lt httpsPassword gt lt httpsPassword gt lt server gt lt lan gt lt rendezvous_ipv4 gt 192 168 0 5 lt rendezvous_ipv4 gt lt rendezvous_ipv4_port gt 9701 lt rendezvous_ipv4_port gt lt rendezvous_ipv6 gt lt rendezvous_ipv6_port gt lt lan gt lt interface gt lt netInterface gt eni lt netInterface gt lt interface gt lt internet_lan gt lt choice gt lan lt choice gt lt proxy gt false lt proxy gt lt ipv6 gt false lt ipv6 gt lt internet_lan gt lt network gt By default the port used by JXSE 54 is the 9701 port but it can happen that a Rendezvous start on one of the subsequent ports such as 9702 or 9703 and so on In this case the user who acts as Rendezvous has the responsibility to communicate the right port to the user who acts as a simple Peer If the JIVES Virtual Environment application is running by using a Internet connection the second user does not have to specify the IPv4 and the port of the Rendezvous because he is not able to know them in advance JIVES automatically queries the Rendezvous directory on the server and provides the right informations in order to connect to a Rendezvous running the same JIVES Virtual Environment
168. r offers to the second one a fishing rod while the second user wants to exchange two hooks At the end of the trade as shown in Figure 6 41 the second user has the fishing rod in his inventory and has no more hooks while the first one has received the two hooks and no longer has the fishing rod Trading with Non Playing Characters can be performed through a different Development and Usage 117 e Monkey Engine 3 0 JivesUser2 Figure 6 38 Trading the selected Item 800 jMonkey Engine 3 0 JivesUser2 Figure 6 39 Confirming the Trade 118 Development and Usage eo jMonkey Engine 3 0 Trade complete Ok Figure 6 40 Trade is complete 800 jMonkey Engine 3 0 Erri ic woodenStick x1 fishingRod X1nylonWire x1 Figure 6 41 The user has received the new Item Development and Usage 119 procedure with respect to the case in which the traders are two Playing Charac ters The NPC has to be activated by selecting the Trade Action The screen proposed in Figure 6 42 will be shown to the user e00 Monkey Engine 3 0 Shop window x v JivesUser Figure 6 42 Trading with a NPC At the top left of the window there is the so called Shop window which informs the user the item s will receive and the item s he has to give in order to accomplish successfully the trade The needed items are to be selected in the Inventory Screen by right clicking the user s avatar and selecting the
169. ray e saveState persists the current state of the JIVES registry The file will be saved as name of the script state name where state name is the command parameter 1 Parameter name the state name e loadState loads a saved state of the JIVES registry The file loaded will be the one named after the same convention of saveState command 1 Parameter name the state name e makeBag given a Bag definition returns a new JivesBag object 1 Parameter definition the definition of the Bag goes as follows it is a JavaScript Object Notation JSON with one property the bag ID This property value must be an array the collection of the Bag items 44 Design and Implementation Code Snippet 5 4 Bag definition bagld id a categories i combines Some combination examples new BagGraphHotspotIntf nail i null bagItemIa new BagGraphHotspotIntf bagItemId 1 model new BagItemModelIntf commonActionsRenderer Po Each Bag item is defined in JSON too It defines the following prop erties a b id Optional The ID of the Bag item useful to refer to it will be generated if omitted categories an array of strings that defines the categories this item is into The item will be in any case categorized under CAT EGORY_DEFAULT even if this is empty combines an array of combination definitions Each combination is an array
170. rge net Find Create and Publish Open Source software for free http sourceforge net Oct 2011 25 GOOGLE Inc Business Photos from Google http maps google com help maps businessphotos index html Sept 2011 26 GOOGLE INC Google Maps with Street View http maps google it intl com help maps streetview Sept 2011 27 HALEPOVIC E AND DETERS R The JXTA performance model and evaluation Future Gener Comput Syst 21 March 2005 377 390 28 HEMMINGER S Netem http swik net netem Nov 2011 29 Hu S Y AND CHEN J F Von a scalable peer to peer network for virtual environments Ieee Network 20 4 2006 22 31 30 INGLES B The future of Java game development In Proceedings of the 44th annual Southeast regional conference New York NY USA 2006 ACM SE 44 ACM pp 698 701 31 JMONKEYENGINE jMonkeyEngine 3 0 Java OpenGL Game Engine http jmonkeyengine com Aug 2011 32 KHRONOS GROUP OpenGL The Industry Standard for High Performance Graphics http www opengl org Aug 2011 BIBLIOGRAPHY 187 33 34 35 36 37 38 39 KIENZLE J VERBRUGGE C BETTINA K DENAULT A AND HAWKER M Mammoth a massively multiplayer game research frame work In Proceedings of the 4th International Conference on Foundations of Digital Games New York NY USA 2009 FDG 09 ACM pp 308 315 KIRNER T G KIRNER C KAWAMOTO A L S C
171. rk NY USA 2008 NetGames 08 ACM pp 34 39 9 CAI W LEE F B S AND CHEN L An auto adaptive dead reck oning algorithm for distributed interactive simulation In Proceedings of the thirteenth workshop on Parallel and distributed simulation Washington DC USA 1999 PADS 99 IEEE Computer Society pp 82 89 10 CHAN L Yona J BAI J LEONG B AND TAN R Hydra a massively multiplayer peer to peer architecture for the game developer In Proceedings of the 6th ACM SIGCOMM workshop on Network and system support for games New York NY USA 2007 NetGames 07 ACM pp 37 42 11 CoDEWEAVERS WineHQ Run Windows applications on Linux BSD Solaris and Mac OS X http www winehq org Sept 2011 12 CPLusPLUS COM cplusplus com The C Resources Network http www cplusplus com Aug 2011 13 CUBE3 ActiveWorlds Managed NET SDK http awmanaged codeplex com Oct 2011 14 DACHSELT R Hinz M AND MEISSNER K Contigra an xml based ar chitecture for component oriented 3D applications In Proceedings of the sev BIBLIOGRAPHY 185 15 pilla 16 aa 17 18 19 20 enth international conference on 3D Web technology New York NY USA 2002 Web3D 02 ACM pp 155 163 DALPANE A Netbeans plugin Mozilla Rhino content assist http plugins netbeans org plugin 39133 Aug 2011 DALPANE A AND SEGALINI S Java Interactive Virtual Enviro
172. rk parameters that interested him the new network configuration can be saved by clicking the Save button while by clicking the Back button JIVES returns to the previous black screen without modifying any network parameter In order to load a JiveScript Virtual Environment script the jME 31 Imple mentor provides a full functional console called JiveScript Console through which it is possible to launch all the commands previously seen for the Shell Demo un less some commands specific for the Shell Implementor In order to visualize the JiveScript Console the user has to type the F1 key of the keyboard On a MAC keyboard the JiveScript Console appears by using the Fn F1 key combination The JiveScript Console is shown in Figure 6 23 en Monkey Engine 3 0 Figure 6 23 JIVES JiveScript Console 106 Development and Usage The list of commands can be displayed by typing the help command in the JiveScript Console Sample ME JiveScript A ME 31 Demo has been developed in order to show the proper functioning of a JIVES 3D Virtual Environment application built by using the ME 31 Im plementor Once JIVES has been started the user has to open the JiveScript Console by typing the F 1 key on the keyboard and launch the load command passing the protocol file and the absolute path in which the JiveScript is lo cated The right JiveScript to be loaded is the basic demo jme jives file When th
173. ronment system and the Rendezvous directory server page are fully reported in the Appendices Chapter 2 Technological background There are several technologies that allow the construction of distributed virtual reality systems In the next subsections will be considered only some of these technologies with particular attention to those most used in the last years It is important to remark that all the technologies presented in this chapter were taken into account for the JIVES project but only some of them were actually used 2 1 VRML The Virtual Reality Modelling Language VRML 70 established a standard for the description of Virtual 3D Environments that can be viewed locally or transferred through the Internet and provides powerful resources for modelling complex 3D scenes It is responsible for showing the virtual scene to the user VRML is often used in combination with the Java 51 development language and the bridge used to communicate this language with VRML is the External Authoring Interface 69 In the last ten years many 3D middlewares frameworks and virtual worlds were created by using the VRML technology 34 2 36 3 2 2 X3D The Extensible 3D X3D 71 is the successor to the VRML It improves upon the latter with new features advanced APIs additional data encoding formats and a 8 Technological background component based architecture X3D has been chosen as the description language of the componen
174. rrect url to the user or set it as the default con figuration setting The urlSecretKey field is related to the account identification each account is associated to a secret key known only to the system it is used on the account behalf to perform important operations like storing the application state This field has been set by default to a web page hosted by Sourceforge 24 in order to show the proper functioning of this feature when running the Demo Also in this case the JIVES developer has to provide to the user the correct url or set it by default in the networkConfiguration default cml file The last two fields of the server tag are related to the account login on the server using an HTTPS connection to the urlSecretKey mentioned before Another feature that can be set modifying the networkConfiguration rml file is the possibility to connect to the Internet also when the connection works under a Proxy In this case the user has to set to true the proxy field and define all the fields under the user tag the url of the Proxy server the port to which the user has to connect the username and the password to establish a working connection to the Proxy server Sample Shell JiveScript In order to show the proper functioning of a JIVES Virtual Environment appli cation built using the Shell Implementor a Shell Demo has been developed The whole logic of the Demo has been written directly by using the JiveScript lan guage the user has
175. rsistence Layer the Actions and Events Management System the Dialogues Manager and finally the Bag Graph BG The Universal Platform has been designed in this way to let the developer immediately start writing his own product since the JIVES Universal Platform includes all the main features of a Virtual Environment According to the VESLOM approach 45 the modules we provide in addition to the Universal Platform are the Networking Layer which has the responsibility to manage all the networking functionality and all the components encompassed in the Middleware Layer The Networking Layer implemented by default in the JIVES framework is based on a Peer To Peer technology the JXTA 54 technology and in particular its Java 51 version JXSE The decision to choose a Peer To Peer technology is dictated by the will to offer to the JIVES developer the possibility to create its own Virtual Environment that can be used also online at Design and Implementation 29 no cost The Middleware layer includes all the remaining components necessary to build a Virtual Environment In particular the Middleware Layer includes the Presen tation module and all the possible extensions introduced by the JIVES developer The Presentation layer also called Engine Implementor offered by default in the JIVES framework is based on the MonkeyEngine 31 technology and provides the possibility to create a completely 3D Virtual Environment Application T
176. rtDialogueAction Jives generateld scene0NPCODialogue0Dialogues question Have a nice day answer Goodbye dialogueModel gui makeDialogue 4 sceneONPCODialogueODialogues question Can I trigger any action during a dialogue answer Of course Here an action is triggered and then the dialogue continues actions new org jives core JivesAction inDialogueAction new org jives sim JivesActionModelIntf execute function jivesEvent gui notification Light blinks and walls tremble fiorita wmoment 0 getDescription function return In dialogue action render function jivesRenderableIntf gui notification 128 Development and Usage this getDescription new org jives actions StartDialogueAction Jives generateld scene0NPCODialogue0Dialogues dialogueModel gui Bind dialogues to NPC sceneONPCO new org jives core JivesActiveNode scene0NPC0 new org jives implementors engine shell ActiveNodeRenderer org jives implementors engine shell ActiveNodeRenderer TYPE_NPC Guy in the southwest corner scene0 addActiveNode scene0NPCO scene0NPCO bindAction new org jives actions StartDialogueAction scene0NPCODialogue0RootAction scene0NPCODialogue0Root getId The JiveScript Demo proposes also a trade between a Playing Character and the Non Playing Character of the initial scene The trade is defined in the J
177. s updates and so on HotspotRenderer model of the Bag Graph hotspots NPCRenderer used to introduce Artefacts in the scene PlayingCharacterRenderer used to represent the avatar of self the local player and those of the other people running the same application PortalRenderer used to represent doors that allow access to different scenes defined in the application script SceneRenderState model of the scene that allows to quickly setup re mote dialogues and trade transactions for the avatars in the scene ShopCatalog used to setup trade transactions with NPCs This isn t by any mean the unique or the most aesthetically attractive or cleanly coded version of the ME 31 Implementor it is just a very simple way to demonstrate that once an Implementor is written many different but similar application scripts will be runnable by it and they all will presenting the features Design and Implementation 71 this Implementor offers like 3D environment inventory representation and man agement interactive combinations and so on without the need to reinvent the wheel The GUI interaction is handled in pure Nifty 43 style introducing screen controllers one for each screen The most difficult part of the job was handling the multi threading correctly as Nifty 43 is not thread safe and GUI can only be updated like scene graph though at precise moments during execution more over multi threaded even
178. s a brief analysis of the previous work in the literature along with the introduction of our new Virtual Environment system JIVES Chap ter 4 includes the motivations and the targets behind the choice of creating the JIVES middleware while Chapter 5 is subdivided into two main sections the first dedicated to the design of JIVES while the latter to the implementation of the framework The implementation section is in turn divided into nine parts each of them involving a specific piece of JIVES the Core the Persistence Layer the Actions and Events Management System the Dialogues Manager the Bag Graph the Networking Layer related to the JXSE 54 technology the Middle ware Layer which includes the description of the Shell Implementor and the ME 31 Implementor and finally the Application Layer which describes the JIVES scripting language JiveScript Chapter 6 regards Development and Usage the 6 Introduction Development section offers a Developer s Manual while the Usage section includes a User s Manual and the accurate description of how the JiveScript Demos have been developed and structured Chapter 7 illustrates the Performance Metrics both qualitative and quantitative and the Evaluation based on the key points of the Design phase and the Performance Metrics Chapter 8 draws the conclusions and possible future works The UML class diagram the JiveScript Demos written to test the proper functioning of the JIVES Virtual Envi
179. s is a textual adventure engine that uses Jives Shell implementor and JiveScr ipt Say help for a list of available commands SCENE 0 This room has a door and there s a guy in the southwest corner Use lookAround to have a further object description Scripting is no longer allowed Starting network on localhost 9701 Ready lookAround The following are the elements of Scene 0 scene0PortalTol Portal to Scene 1 scene0NPCO Guy in the southwest corner me Undefined position Ready lookAround The following are the elements of Scene 0 scene PortalTol Portal to Scene 1 scene NPCO Guy in the southwest corner JivesUser Undefined position Ready Figure 6 15 JiveScript Shell Demo Starting Scene Ready lookAround The following are the elements of Scene 0 scene PortalTol Portal to Scene scene NPCO Guy in the southwest corner JivesUser Undefined position JivesUser2 Undefined position Ready Figure 6 16 A New Entry in the Scene Development and Usage 97 networkConfiguration cml file the IPv4 and the port used by the first user that acts as a Rendezvous as shown in Code Snippet 6 4 Code Snippet 6 4 JIVES Peer Network Configuration Settings lt zml version 1 0 encoding UTF 8 standalone no gt lt network gt lt jives gt lt jivesUsername gt JivesUser2 lt jivesUsername gt lt jives gt lt user gt lt proxyHost gt lt proxyPort gt lt proxyUsername gt lt
180. s of the framework provides the powerful possibil ity to extend the framework itself by adding new functionalities or by replacing the existing one with new implementations The developer benefits of this sub division because he does not have to reinvent the wheel each time he wants Related work 17 to create a new Virtual World but he is free to reuse the modules offered by OpenPING and other modular Virtual Environments middlewares in order to implement a specific functionality in his project Contigra Component OrieNted Three dimensional Interactive GRaphical Applications 14 is another effort to build a component based architecture on the basis of X3D and XML designed for the construction of web based desktop Virtual Reality applications and 3D Virtual Environments The Contigra project pays great attention to the concepts of reuse by providing a methodological approach largely independent of imple mentation issues Also Java Adaptive Dynamic Environment JADE 46 and Mammoth 33 supply a full modularity function adding a proper Module Man ager in order to easily administrate the modules implemented in the framework Recently the Open Wonderland project 47 has attracted attention in the Virtual Environment middleware industry Open Wonderland is a 100 Java 51 Open Source toolkit for creating collaborative 3D worlds One of the best features that led Open Wonderland to success is just the possibility to extend any par
181. sScene getMyself getProperties put position position if action instanceof org jives actions BagltemAction 4 if bag0 getQuantity coin lt 2 4 gui notification Listener Received action getItem return false else 4 IDE getId gui notification Listener You already have enough eoans return true JiveScript ME Demo 169 if action getId equals openCoffer try 1 cofferOpened Jives get cofferOpened java lang String cerca 6 u cofferOpened false Ip if cofferOpened false Jives put cofferOpened true return false else Y gui notification Listener The coffer is empty return true return false getId function return inventoryListener DE Jives registerEventListener inventoryListener Define bago bag0 makeBag 4 bag0 id apple categories received combines model new org jives implementors engine jme BagItemRenderer Models apple apple mesh zml 0 1 An apple received trading with that strange guy commonActionsRenderer gui id eoin categories received combines new org jives implementors engine jme HotspotRenderer com jme3 math Vector3f 5 5 5 2 Y null l model new org jives implementors engine jme BagItemRenderer Models coin coin mesh zml 0 1 A coin received talking to that strange guy comm
182. scenei addActiveNode sceneiPortalTo0 sceneiPortalTo0 bindAction new org jives actions PortalAction scenelPortalTo0Action scenel scene0 164 JiveScript Shell Demo Zi Door e serna B 2S 2 2 2 so esse See SSeS Sac Sean 20222022222 sceneiPortalTo2 new org jives core JivesActiveNode sceneiPortalTo2 new org jives implementors engine shell ActiveNodeRenderer org jives implementors engine shell ActiveNodeRenderer TYPE_PORTAL Portal to Scene 2 DE scenel addActiveNode sceneiPortalTo2 sceneiPortalTo2 bindAction new org jives actions PortalAction scenelPortalTo2Action scenel scene2 Le Bayer SR SS SS SS SS a sceneiCoffer new org jives core JivesActiveNode scenelCoffer new org jives implementors engine shell ActiveNodeRenderer org jives implementors engine shell ActiveNodeRenderer TYPE_NPC Coffer scenel addActiveNode sceneiCoffer scenelCoffer bindAction new org jives core JivesAction openCoffer new org jives sim JivesActionModelIntf 1 execute function jivesEvent bag0 addBagIten Jives get woodenStick org jives core JivesBagItem 1 bag0 addBagIten Jives get nylonWire org jives core JivesBagItem 1 bag0 addBagIten Jives get hook org jives core JivesBagItem 2 gui notification Received a wooden stick a nylon wire and tio hook getDescription function return Open coffer render function jivesRenderab
183. sible to improve applications like Google Business View 25 a tool that allows you to view the inside of stores through a 360 degree imagery based on the Google Street View Technology 26 by adding an additional layer of Immersivity the Interactivity By using JIVES the developer can create a specific application to let the user to not just visit the online store but also interact directly with it by exploring the shop and examining the products The Virtual Worlds created by using our framework must have the element that we believe the most important one in a Virtual Environment application an enjoyable participatory experience So that the implementation of the Virtual Environment must have enough performance to allow for a smooth virtual expe rience and the application states perceived by the participants must be similar enough to not give an unfair advantage to any of the users The choice of a Peer To Peer architecture used to implement the Networking layer aims to have at most a hundred users simultaneously connected in the same Virtual Environment that number of participants is more than enough to achieve a fully enjoyable online experience There are a lot of studies that prove the excellent scalability of this kind of network architecture in particular Hu and Chen 29 have successfully tested a Peer To Peer network consisting of more than 2000 nodes Chapter 5 Design and Implementation 5 1 Design The design phase of t
184. simply aborted 5 1 4 Networking Layer Architecture The Network Architecture is essentially the one offered by the JXTA 54 technol ogy The JXSEImplementor represents the JIVES Network Layer and implements all the network functionalities of the framework While designing the Implemen tor only the Core Layer of the three Layers that make up the JXTA 54 architec ture has been taken in consideration There is no need to adopt also the Services Layer and the Application Layer because JIVES requires only the minimal and essential primitives that are common to Peer To Peer Networking This includes the key mechanisms for a Peer To Peer application such as Peers discovery com munication transports creation of Peers and Peer Groups all services belonging to the JXTA 54 Core Layer The JXTA 54 Architecture as specified in 68 provides a subdivision of the Peers into three main categories e Minimal Edge Peers Peers that implement only the required core JXTA 54 services e Full Edge Peers Peers that implement all the core and standard JXTA 54 services and can participate in all of the JXTA 54 protocols e Super Peers Peers that implement and provision resources to support the deployment and operation of a JXTA 54 network There are three Super Peer functions Relay used to store and forward messages between Peers that do not have the direct connectivity because of firewall or NAT Rendezvous maintains global
185. sing the activate bag0 command as shown in Figure 6 18 Once the user has in his Inventory Bag some items he can combine them by using the combine action for each selected item the user must choose the right Development and Usage 99 eN LJives java 81x42 ma JivesUser gt gt scene NPC Can you give me an item to put in inventory scene0NPCO gt gt JivesUser I can but for demonstration the limit has been set to two items only Listener Received coin 9 X Can you give me an item to put in inventory 1 Can I trade items from my inventory 2 Can I trigger any action during a dialogue 3 I ve understood thank you Which question to ask JivesUser gt gt scene NPC Can you give me an item to put in inventory scene0NPCO gt gt JivesUser I can but for demonstration the limit has been set to two items only Listener Received coin 9 X Can you give me an item to put in inventory 1 Can I trade items from my inventory 2 Can I trigger any action during a dialogue 3 I ve understood thank you Which question to ask 3 JivesUser gt gt scene NPC I ve understood thank you scene0NPCO gt gt JivesUser You re welcome 0 X Where am I 1 Who are you 2 Have a nice day Which question to ask 2 JivesUser gt gt scene0NPCO Have a nice day scene0NPCO gt gt JivesUser Goodbye Ready activate bag0 0 Open 1 Activate item 2 Combine items 3 Cancel Which a
186. splay JiveScript version Print the textual representation of an object Print the textual representation of an object with o Evaluate a script Print available and allocated memory Set the flag to allow scripting or not Set the script user readable name Declare and import a dependency Print the list of objects in the registry Return an array of the objects passed as parameters Save state snapshot Load state snapshot Create a new JivesBag Create a new JivesDialogue Figure 6 14 List of Shell Implementor and JiveScript Commands Development and Usage 95 they may change according to the Implementor the JIVES application is running the second ones are related to the JiveScript language The first operation the user has to perform once JIVES has been started is obviously load the JiveScript Shell Demo This is possible by typing the command load file path of the Jive Script Shell Demo Note that the user has to specify the absolute path of the JiveScript Demo The first part of the argument of the load command file represents the protocol used by JIVES to load the file the second part is the path of the location in which is located the script For example in a MAC OS X environment if the JiveScript Demo has been located on the Desktop the user has to type load file Users user Desktop basic demo shell jives where user is the name of the operating system user When loading a script Win dows users has to s
187. t all our effort in writing a smart and working implementation while investigat ing many of the aspects that commonly concern this kind of development We were not interested in creating a 3D Virtual Environment in itself but to create something more an experimental system that would help others create their own 3D applications The JIVES framework aims to be a starting point in the direc tion of creating a Virtual Environment framework that includes all the features needed in the development of such applications By analysing the literature of the last decade we realized that a lot of problems have plagued the development of Virtual Environment systems Starting from the ashes of an old project of 2008 16 we decided to completely redesign the JIVES framework in order to obtain a new system that keeps pace with the times and takes into account the 24 Motivations and targets problems that have afflicted the development of Virtual Environment systems in recent years such as scalability extensibility and ease of use Because of this the JIVES framework has been designed modular regarding the Presentation and Networking layers in order to face the extensibility issue and the currently pro vided network module is based on a Peer To Peer architecture in order to take into account scalability issues related to a client server architecture The modularity of the JIVES framework would let the developer implement a different network module may
188. t actions were needed because requests to the SIMs are locking when they need to receive user input while on the other side the graphic engine process must not be locked otherwise there is no way the user can interact with the GUI This problem was solved defining all NiftyUpdatableIntf implemen tor classes to be registered at any time and then at the right time called to process the updates to the GUI The best approach to achieve this results is a Runnable instanced inline as proposed in Code Snippet 5 8 Code Snippet 5 8 Nifty GUI Multithreading public abstract class GUIBuilder implements Runnable NiftyUpdatableIntf Override public void onUpdate float tpf run implementor unregisterNiftyUpdatable this GUIBuilder builder new GUIBuilder public void run TE SW AN y y implementor registerNiftyUpdatable builder Unfortunately this pattern was not followed strictly along the code but this would be the best solution when writing a real ME 31 Implementor for JIVES 72 Design and Implementation 5 2 4 Application Layer The Application layer of the JIVES framework has been designed with the idea to offer a new smooth and interactive way to write 3D Virtual Environment ap plications this is possible through the use of the JiveScript scripting language JiveScript has been introduced in the JIVES framework to let the developer de fine efficiently its own 3D Virtual Environment specify
189. t geometry due to its flexible XML encoding modularization and backward compatibility with VRML 70 data 14 35 Furthermore X3D includes a rich set of primitives for modelling 3D geometry behaviours and interactions 3 2 3 Java3D Java3D 48 is a scene graph based 3D application programming interface API for the Java 51 platform It runs atop either OpenGL or Direct3D Java 3D is not only a wrapper around these graphics APIs but an interface that encapsulates the graphics programming using a true object oriented approach A scene is constructed using a tree structured scene graph that is a representation of the objects that have to be shown Several projects employed Java 3D 2 36 3 65 2 4 JOGL Java OpenGL JOGL 53 is a wrapper library that allows OpenGL to be used in the Java 51 programming language JOGL allows access to most features available to programs developed using C with the notable exception of window system related calls in OpenGL Utility Toolkit GLUT since Java 51 has its own windowing systems Abstract Window Toolkit AWT and Swing Over the last years different graphical engines have been implemented on top of JOGL 33 2 5 LWJGL The Lightweight Java Game Library LWJGL 55 is an Open Source Java 51 software library for game developers LWJGL exposes high performance cross platform libraries commonly used in developing software applications such as Technological background 9
190. t of the system and add functionality by creating modules the Wonderland version of plugins Oliveira 45 presented the Virtual Environment System Layered Object Model VESLOM providing a complete approach to design fully modular Vir tual Environment frameworks The aim underlying VESLOM 45 is to reduce the complexity related to the design of a Virtual Environment middleware by divid ing it into different layers Starting from the core functionality provided by the so called Universal Platform the developer selects the appropriate components for his application such as the Networking layer the Middleware layer and the Application layer The VESLOM 45 was successfully used in the creation of the Java Adaptive Dynamic Environment JADE 45 a fully modular Virtual Environment system Other Virtual Environments middlewares focus on the collaborative aspect these middlewares are called Collaborative Virtual Environments CVE frame 18 Related work works According to the definition specified in 34 a CVE is a multi user Collab orative Virtual Environment that runs on the Internet Several projects involve the creation of specific tools through which it is possible to create Virtual Worlds CVE VM 34 is a Collaborative Virtual Environment tool created aiming to sup port the teaching learning in Brazilian schools The CVE VM implementation uses VRML 2 0 and Java 51 languages integrated by the EAI External Author ing I
191. ted the JIVES Applet by using Firefox The forth and last experiment was about the development of a JIVES ap plication Due to the short time available the users were asked to write a new JiveScript without the need of developing new Implementors but by using the default ones provided by JIVES The application had to be something very similar to the JiveScript ME 31 Demo a Virtual Environment with few Non Playing Characters and Artefacts One day of time has been given to accomplish the request Both users successfully installed the Netbeans 56 IDE and the plugin needed in order to benefit of the auto completion feature provided by the Jive Script editor Netbeans plugin 15 The medium expert user was able to develop a new JIVES application by writing a new JiveScript using the default Implemen tors provided by the framework and the same meshes adopted in the development of the ME 31 Test Demo The outcome is a 3D Virtual Environment which 142 Performance Metrics and Evaluation offers two different scenes in which are located two Non Playing Characters with a pre defined dialogue and two Artefacts The user has also defined a short plot which consists in collecting some items combining them together and trading them with the Non Playing Characters in order to perform a specific action pos sible only if the avatar owns particular items At the contrary the newbie user nevertheless he installed correctly all
192. tel renderi serializel setactivable setPropertiesi freezel getidl getNamel getPid handleEventi unfreezel JIVES Class Diagram 157 ii org jives impl lementor Enginelmplementorini Networkimplementorin exitt loopl resetl setupl getAccountSecretkeyl getConnectionState gettocaladdress getRemotePeersinfol sendMessage startNetworkl stopNetworkl e activate e bindAction gt E getactivationeventi gettvailableActionByidi getAvallableactions getparenti setparenti e unbindActioni JivesScenel unfreezel setRendereri toStringl addactiveNode unfreezel freezel getidl toStringl unfreezel JivesObjectint isselectionchangedi removeBagitemi setProperties setSelectedQuantity4 amp JivesActioni jivesBagl Jivesctioni activate e freezel addBagiteml e getidi e bindcommonaActions e getModelTypel o fre 0 e O getProperties getCategoriesNotEmptyi o O getRendereri setid o e getSourcel e getitems e e getTargeti getitemsinCategoryi e setPropertiesi e getProperties setRenderer getQuantity e setSourcel e getRenderer e setTarget getSelecteditems o e toString O getSelectedQuantity o o o o o o o o amp
193. tent PID rendezvous gt getElementsByTagName pid gt item 0 gt textContent time rendezvous gt getElementsByTagName time gt item 0 gt textContent if program _GET program MD5 _GET md5 nodesToRemove rendezvous foreach nodesToRemove as node node gt parentNode gt removeChild node doc gt save APPLICATION_DIRECTORY rendezvous_ _GET program xml echo Query completed break case queryinactive doc new DOMDocument doc gt preserveWhiteSpace false doc gt load rendezvous xml doc gt formatOutput true root doc gt documentElement rendezvous_list root gt getElementsByTagName rendezvous nodesToDelete array programFilesToKeep array filesToDelete array foreach rendezvous_list as rendezvous program rendezvous gt getAttributeNode program gt value MD5 rendezvous gt getAttributeNode md5 gt value IPv4 rendezvous gt getElementsByTagName ipv4 gt item 0 gt textContent IPv6 rendezvous gt getElementsByTagName ipv6 gt item 0 gt textContent port rendezvous gt getElementsByTagName port gt item 0 gt textContent PID rendezvous gt getElementsByTagName pid gt item 0 gt textContent time rendezvous gt getElementsByTagName time gt item 0 gt textContent if _GET time tim
194. teractive question an swer paradigm In both cases the entrance into dialogue mode consists in the activation of an Active Node using a StartDialogueAction While PC dialogues are simple chat and don t offer any other feature than textual communication between two or more peers in a chat room NPC dialogues are much more versatile In the latter there can be multiple paths of interrogation that lead to different results but that 60 Design and Implementation in general do nothing more than triggering actions any kind of action So for instance its possible to acquire inventory items by talking to NPCs or playing cinematics and whatever else Dialogues are defined in JiveScript with a very rigid JSON JavaScript Object Notation that define each Dialogue Request in a list every request specifies a question and its answer plus the actions triggered by choosing that Dialogue Request To create a dialogue the JSON object is passed as parameter of the makeDialogue JiveScript command The dialogue can be attached to any Active Node by binding a new StartDialogueAction on it Bag Graph Underneath a JIVES Bag object the delegation resolves to the Bag Graph and to a SIM This graph defines which items can be contained in this inventory which are their possible combinations in order to produce more Bag Items and how this combinations must be performed interactively by the end user on the other side the model exposes methods that n
195. the Architecture for Large Scale Virtual Interactive Com munities ALVIC framework Quax used the autonomous avatars to simulate a large scale multi user networked environment providing a method for scalability testing eliminating the need for large numbers of human users and obtaining ac curate results by only using a limited number of computers Other researches 17 focus instead on the performance requirement providing enhancement techniques related to the synchronous communication needed in a Virtual Environment in order to obtain a good quality of the experience The majority of the Virtual Environment systems described above tried to solve some of the distributed problems inherent the design of Virtual environ ments but they were based on monolithic architectures making difficult mainte nance and software reuse Projects are often developed from scratch and involve a great deal of programming without reusing building blocks OpenPING 44 a reflective middleware for the construction of adaptive networked game applica tions is one of the first Virtual Environments middlewares which aims to reach the flexibility maintainability and extensibility requirements by providing an ar chitecture implementation entirely based on modules such as the Concurrency module the Replication module the Interest Management module the Persis tence module the Consistency module and the Event Channelling module The separation of the functionalitie
196. the sub folder states 6 2 3 Java Applet Users Manual A JIVES Virtual Environment application can be deployed also as a Java 51 Applet that runs inside a web browser In order to test this feature the ME 31 Demo has been published at the following URL http simonesegalini altervista org jives test test html An essential prerequisite to correctly run the JIVES Applet is to grant the right permissions to the application in order to access the user s computer This is possible by providing a trusted certificate with which the applet is signed For testing purposes however it s sufficient to place the java policy file in the right location in a Windows OS this file has to be located in C Documents and Settings user java policy or CA Users user java policy depending on the specific Windows version in a MAC OS X Environment in Users user java policy under a Linux system in the home directory home user java policy The java policy file is not provided to the user he has to create it manually open it with any text editor and insert the content shown in Code Snippet 6 5 Development and Usage 121 Code Snippet 6 5 The Policy File Do what you will Totally permissive policy file grant permission java security AllPermission IPB When accessing the Launcher Page for the JIVES Applet a message box as shown in Figure 6 43 displays the request that the JIVES Applet wants to access to the
197. third approach may be implemented in the JIVES framework according to the JXTA 54 Network Architecture the Peers participating a Virtual Envi ronment can be divided into several Peer Groups each of them with a specific Peer Group ID In that way the developer after implementing a new Networking Layer Implementor with this particular feature can manage the dissemination of messages according to the subdivision into Peer Groups a message may be re ceived only by some Peer Groups and not by another ones This kind of approach may be called Group based Approach JIVES has been designed to implement a subdivision of Peers according to the Virtual Environment application they are running only Peers executing the same JIVES application can communicate each other Within the application JIVES does not implement any kind of Interest Management each message is sent fully broadcast to every Peer participating the 66 Design and Implementation same JIVES application The possibility to implement an Interest Management scheme is left to the developer JIVES Peers communicate using JXTA 54 messages each message is sent through the Transmission Control Protocol TCP in order to have a reliable transmission In the JIVES implementation each message consists of a serialized object called NetworkMessage in which there are the basic informations needed for a given action or transaction Code Snippet 5 7 NetworkMessage constructor xk
198. ting language JiveScript has been introduced in the JIVES framework to let the developer define efficiently his own 3D Virtual Environment specifying the whole logic of the application the virtual 30 Design and Implementation objects their relations and behaviors The Class Diagram of the JIVES project is fully reported in Appendix A It is important to stress that the JIVES framework has been designed to be independent of the reference implementation due to the use of the Java 51 programming language Java 51 programs are platform independent and can be executed in every operating system through the use of a Java Virtual Machine In order to speed up the writing of the boilerplate code and ease its maintainability JIVES has been developed using the Lombok 75 technology particularly for the accessor and delegate methods generation 5 1 1 Inventory Data Structure A fundamental aspect of the proposed design consists in the fact that every char acter has his own eventually more than one inventory also referred to as bag for brevity The character is able to switch between any of his bags extract items to use in the environment or to exchange with others and he can perform other actions on those items like examining them or combining them Combination plays a major role in this interaction We introduce a new paradigm where the end user must decide not only which items to combine but eventually in which way to com
199. to enable a sandbox modality through which he has the possibility to freely experience some changes in the JIVES application he s developing Development and Usage 123 The Setup section of the JiveScripts define the listeners and the item combi nations provided by the application The JIVES framework manages the events through an event based system each event generated inside the application has a condition and an action If the condition is verified the action is executed Through the use of listeners or better called event listeners there is the possibil ity to notify and manage the event executing or inhibiting the associated action As shown in Code Snippet 6 7 in the JiveScript Demos the user s avatar can receive from the NPC of the first scene at most two coins in the case the user asks for a third coin the listener inhibits the action associated to the given event Code Snippet 6 7 Event listener Define a listener inventoryListener new org jives events JivesEventListenerIntf 1 handleEvent function jivesEvent action jivesEvent getAction if action instanceof org jives actions BagltemAction if bagO getQuantity coin lt 2 4 gui notification Listener Received action getItem getId return false else gui notification Listener You already have enough cons s return true return false Ip getId function return inventoryListener
200. tory jives default builds the JIVES library e implementor engine shell builds the Shell mplementor e implementor engine jme builds the JMEImplementor e implementor network jxse builds the JXSEImplementor e testNetworkApp builds a test application to run a JXSE Peer in SWING e testShell builds a test application that uses the Shelllmplementor and the JXSEImplementor e testJME builds a test application that uses the JMEImplementor and the JXSEImplementor Moreover there is the possibility to export the JMEImplementor directly as an applet using MonkeyEngine 31 SDK so that it can run in the web browser You just need to be sure that the project is configured to be built as an applet Development and Usage 83 This can be done in the project properties window Application section Applet subsection Create Applet has to be checked The appropriate class to run as an applet can be found in the org jives test package and it s called TestJMEA pplet The peculiarity of this class is that it extends JMEImplementor in order to run as an applet as can be seen in Code Snippet 6 1 Code Snippet 6 1 TestJMEApplet public class TestJMEApplet extends JMEImplementor 4 public TestJMEApplet 4 super Override public void simpleInitApp Log setLogLevel Log LOG_ERROR instance this Jives setEngine instance Jives setNetwork JXSEImplementor getInstance super simpleInitApp Run
201. ts that can support collaborative projects or virtual cities museums art galleries and labs JIVES supports the creation of a large range of applications To perform a better estimation of the performance of the Peer To Peer so lution however a small number of Peers is not sufficient A cheap solution is performing the emulation of a wider network to understand the asymptotic be haviour of the network load The trade off consist in the fact that emulating a large number of applications on a single physical machine has the effect of a rapid degradation of the system responsiveness this fact is going to drastically alter the trustiness of the evaluation as soon as the number of running Peers grows it can be easily seen observing the increasing variance of the data plotted in Figure 7 2 146 Performance Metrics and Evaluation In any case a linear trend clearly emerges from the regression line this is an encouraging result if viewed in the perspective of the traditional Client Server approach where network load is exponential on the number of the connected Peers An important observation to be done is that this is the worse case in which n 1 Peers concur to contacting the n th one this tells us that JXSEImple mentor is able to deliver the messages of 10 peers under 5 seconds on a network with the following characteristics DSL Downlink bandwidth 7 Mbps Download Delay 100 ms Uplink Bandwidth 2 Mbps Uplink Delay 100 ms In terms
202. tual Environment System JIVES JIVES is completely Open Source and released under the GNU General Public License 3 0 GPLv3 22 All the technologies employed in the creation of the JIVES framework are Open Source based JIVES has been designed following the VESLOM 45 approach in order to make it modular and extensible JIVES is composed by a Universal Platform which provides the core function alities of the framework a Networking layer and a Presentation layer According to the VESLOM 45 approach the Universal Platform represents the kernel of the middleware JIVES is provided by default with a Presentation Layer and a Net working Layer the first implemented by using the MonkeyEngine 31 the latter by using the JXTA technology 54 facing in that way the scalability problem related to Client Server architectures The modularity offered by JIVES allows the developer to implement any other kind of Presentation Module and Network 20 Related work ing Module using different technologies than the ones implemented by default The extensibility offered by JIVES lets the developer fully personalize some of the features of the framework in addition to the actions and events implemented in the framework new customized actions and events can be defined and used in the development of a new Virtual Environment Because of the choice of a Peer To Peer architecture the JIVES framework is not properly suitable for the creation of Mass
203. ture allows JIVES to take care of the expected features for instance action execution inventory manage ment traversing scenes and so on while it allows to freely define specific features that typically the application must cope with for example the effect of an action being executed the shapes and quantities of the items in the inventory the way an end user traverse from one scene to another This duality is achieved in Java 51 without the usage of multiple inheritance but with delegation instead This is why the above described model resolves to a list of interfaces the Structured In teractivity Models SIMs whose implementation changing from one application to another gives shape exactly to the needed virtual environment A last issue comes with the representation of the JIVES objects Being this a tipical implementor issue it differs depending on its capabilities meaning that a command line interface would have a textual representation of the objects while for instance a graphic engine would render 3D geometry to represent them To decouple system rendering calls from their real implementation a set of renderable entities is defined and to each of them a respective renderer from the implementor is associated in order to maintain a very high degree of interoperability Structured Interactivity Models The interfaces contained in package org jives sim are used to create JIVES ob jects in JiveScript or in Java 51 and are calle
204. ty to define for each virtual item a list of its possible hotspots or attachment points through which the item can be com bined with another one In that way the developer is able to define more complex and meaningful combinations than those usually possible in the current Virtual Environments middlewares We want to offer a product extensible and renewable by the addition of new modules and customizations that allows the creation of new 3D Virtual Environ ments The freedom that we offer to the JIVES user is such that he can develop any type of 3D application using our framework JIVES does not limit in any way the creativity of the developer and it can be even used to create multi access inter active web virtual applications The range of applications that can be developed using JIVES is very large from Inventory based games to training simulations 26 Motivations and targets such as simulations aimed to train the user in critical situations like a fire drill evacuation or simulations used to prepare for a hostile environment the same way a survival course does to collaborative E Learning Virtual Environments such as interactive 3D class rooms or professional working environments that can support collaborative projects or virtual cities museums art galleries and labs By using JIVES the developer can create something that offers more than some of the applications already existing on the market for example it is even pos
205. uming a Rendezvous role or not If the user wants to start as a Rendezvous he does not have to add any thing else at the contrary if he wants to start as a simple Peer and connect to a Rendezvous obviously located in the same LAN network he has to specify the rendezvous 1pv4 and rendezvous_ipv4_port fields filling them with the IPv4 and the port of the Rendezvous to which he wants to connect For example is the Rendezvous has the IPv4 192 168 0 8 and the Port 9701 the right way to config 92 Development and Usage ure the network settings configuration file is to change the rendezvous_ipv4 field in lt rendezvous_ipv4 gt 192 168 0 8 lt rendezvous_ipv4 gt and the rendezvous_ipv4_port field in lt rendezvous_ipv4_port gt 9701 lt rendezvous_ipv4_port gt In the case he wants to use an IPv6 connection the user has to enable it by setting to true the ipv6 field and if he roles as a simple Peer in a LAN network the fields to be correctly set in this case are the rendezvous_ipv6 and rendezvous_ipv6_port ones The IPv6 connection feature provided by JIVES is still an experimental feature and may have some issues in its proper functioning due to the lack of IPv6 connections managed by Italian providers and IPv6 enabled routers A very important field the user has to set is the net nterface field If this field remains unchanged the user can execute the JIVES application only using the loopback interface so the connection works only
206. va project and follow the on screen instruction to create it 2 Download the JIVES project library and extract it in the project folder The final result should be similar to Figure 6 1 myJivesProject x File Modifica Visualizza Vai Segnalibri Aiuto usr src eclipse jives jar 2 oggetti 118 9 GB dispazio libero Figure 6 1 JIVES Project Folder using Eclipse Development and Usage 77 3 From the Package Explorer in the Java Perspective refresh the project then select all the newly added dependencies as shown in Figure 6 2 PackageE 8 Type Hier 550 aS z Y myJives Project src D m JRE System Library java 1 6 0 openj Y 5 lb r commons codec 1 5 jar gt F3 New r commons lang 2 6 jar r db40 8 0 184 15484 Oper Show In Shift Alt w gt r lombok jar Er jives jar E3 Copy Qualified Name Paste Ctrl V Delete Figure 6 2 Adding JIVES Dependencies in Eclipse 4 The project is now configured to use JIVES library Setup guide for MonkeyEngine SDK Netbeans 1 From the File menu select New Project then follow the on screen instruc tion to create a ME3 BasicGame project if you wish to write a ME 31 application a simple Java Project otherwise 2 Download the JIVES project library and extract it in the project folder Figure 6 3 shows how the project folder should look like 3 Right click on the Library
207. veState and the loadState commands the user has the possibility to save a snapshot of the current JIVES application and then reload it in a second moment The argument to be passed to the commands is a string included in double quotes which represents the name of the snapshot to save or load The snapshot will be saved in the sub folder states of the folder called Roaming jives in the AppData directory if the running OS is a Windows system in the folder userHome jives states if the application is executed in MAC OS X Environment or under a Linux OS In order to correctly load a save 102 Development and Usage file the user has first to load the script and then run the loadState command by passing the name of the save enclosed in double quotes 6 2 2 JME User s Manual In order to show the possibility to develop and run full 3D Virtual Environments a ME 31 implementor has been developed The ME 31 Implementor is exactly a 3D restatement of the Shell Implementor In order to launch a JIVES Virtual Environment application the procedure is the same as in the case of a JIVES application built using the Shell Implementor JIVES essentially consists of a runnable jar file executable by launching the java jar testJME jar command in a terminal or a shell When launching JIVES a directory jives Roaming jives in Windows is created and includes a folder called config which in turn has a
208. ven Remote Action that has to be executed in the JIVES Virtual Environment specifying the source and the target of the operation JIVES provides also an additional layer of management of the Peers connected to a JIVES application It is possible to associate to each Peer an account with a given password thereby obtaining a database of all the users who have logged at least once a given JIVES application For each account the server is responsible to release a Secret Key through which it is possible to encrypt the user data giving in that way the possibility to the JIVES application user to restart the Virtual Environment later without losing the application state related to his avatar 5 2 3 Middleware Layer Apart from the network access commonly a JIVES application will need at least to display JIVES entities and make end user interact with them on top of those a more complex application would develop any more sophisticated features it requires This kind of concepts are extremely abstract and heavily rely on the container JIVES is inserted into For the interoperability of JIVES to be as much generic as possible there is no practical way to define a structure in the middleware for every implementors to follow in order to work As a matter of fact the Middleware Layer is left open to any type of imple mentation to cope with radically different needs It is easily understandable that this can bring to a wide variety of applications that c
209. work RemoteActiveNode org jives implementors engine shell SceneRenderState setupTradeAction jivesActiveNode bag0 org jives implementors engine shell SceneRenderState setupRemoteDialogue jivesActiveNode onActiveNodeRemove function jivesActiveNode scenei new org jives core JivesScene Scene 1 sceneiModel sceneOModel new org jives implementors engine shell SceneRenderState new org jives sim SceneModelIntf destroy function OS activate function echo n nSCENE 0 n This room has a door and there s a guy in the southwest corner Use lookAround to have a further object description onActiveNodeAdd function jivesActiveNode if jivesActiveNode getModelType equals org jives network RemoteActiveNode org jives implementors engine shell SceneRenderState setupTradeAction jivesActiveNode bag0 org jives implementors engine shell SceneRenderState setupRemoteDialogue jivesActiveNode onActiveNodeRemove function jivesActiveNode scene0 new org jives core JivesScene Scene 0 scene0Model je FSS 33539559555 5555555 S555 S55555 Scene cen Z JiveScript Shell Demo 163 il Door CA GOTE dl seso SS SaaS a Sane a SSeS Lana scene2PortalTol new org jives core JivesActiveNode scene2PortalTo1 new org jives implementors engine shell ActiveNodeRenderer org jives implementors engine shell ActiveNodeRenderer TYPE_PORTAL Port
210. xt editor the networkConfiguration cml file lo cated in the sub folder jxse of the folder config The first time that the user runs the application it happens that there is not the jives Roaming jives in Windows folder and consequently there are not also the networkConfigura tion default cml and the networkConfiguration xml files If the user has no interest to change the network configuration he has only to start the JIVES application JIVES itself will create the networkConfiguration zml file for the user If the user wants to modify some properties with respect to the default configuration he has to start JIVES at least once even without loading any script in that way the Networking Layer Implementor will create the jives Roaming jives folder and the necessary network configuration files in the predefined location The user has only to modify the content of networkConfiguration cml with a text editor The networkConfiguration rml file can be even modified at runtime but before loading a script once set the network parameters it is sufficient to stop the net work if a script has been previously loaded by launching the reset command and load a new JiveScript with the load command when a new JiveScript is loaded the new settings are read and stored and the network restarted In Code Snippet 6 3 is shown the default network configuration provided by JIVES Development and Usage 91 Co
211. yTagName port gt item 0 gt textContent PID rendezvous gt getElementsByTagName pid gt item 0 gt textContent time rendezvous gt getElementsByTagName time gt item 0 gt textContent if IPv4 _GET addr amp amp IPv6 _GET addr2 amp amp port _GET port amp amp PID _GET pid amp amp program _GET program amp amp MD5 _GET md5 179 180 amp amp time null nodesToDelete rendezvous foreach nodesToDelete as node node gt parentNode gt removeChild node doc gt save rendezvous xml echo Removing completed else echo Removing failed Token not corresponding break case query doc new DOMDocument doc gt preserveWhiteSpace false doc gt load rendezvous xml doc gt formatOutput true root doc gt documentElement rendezvous_list root gt getElementsByTagName rendezvous nodesToDelete array foreach rendezvous_list as rendezvous program rendezvous gt getAttributeNode program gt value MD5 rendezvous gt getAttributeNode md5 gt value IPv4 rendezvous gt getElementsByTagName ipv4 gt item 0 gt textContent IPv6 rendezvous gt getElementsByTagName ipv6 gt item 0 gt textContent port rendezvous gt getElementsByTagName port gt item 0 gt textCon
212. zation introduced by reducing the number of classes loaded by the MultiInstanceEndpoint JXSE 54 class loader has permitted to reduce substan tially also the amount of memory consumed by JIVES starting from an amount of about 600 MB now the ME 31 Test Demo uses approximately 300 MB achieving an improvement of 50 in terms of memory usage Due to the fact that JIVES is executable as a Java Applet experiments have been done in order to test the capacities of the most popular browsers to load and execute the ME 31 Test Demo implemented with the JIVES framework The Demo has been proved to be successfully executed using Mozilla Firefox 132 Performance Metrics and Evaluation Apple Safari Google Chrome the Open Source browser Chromium and Internet Explorer The only browser that failed to run the Demo without even starting it is Opera The execution of the Demo as a Java Applet when using a Windows or Linux Environment system did not reveal any substantial differences in terms of performance metrics while running except for a slightly bigger network lag when compared to the desktop version but it s way slower while loading especially if the applet sign has to be verified for every loaded class This performance decay should not be present when using a trusted certificate At the contrary when running the applet using a MAC OS X operating system were noticed some problems related to the improper handling of input devices espe

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