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Bluetooth Hotspots for Smart Spaces Interaction

1. We have chosen to work with this kind of devices due to many factors referred below Values shown are estimated values obtained from the units we have used as prototypes and also obtained from a sample of the OpenWrt s table of supported OpenWrt Linux distribution http www openwrt org BlueZ is a set of libs and system tools that implements the Bluetooth stack for Linux waw bluez org 68 hardware e Size around 20x10cm eases the installation of a Hotspot in hidden places for environments like bars halls or streets e With a low power consumption around 5 to 10W it becomes possible to deploy a Hotspot or a group of them without high energy consumption issues e clock around 250MHz and the available memory around 16MB proved to be more than enough to run the entire OpenWrt system and our prototype Hotspot s software without loss of performance comparatively to the performance of the development prototype environment on a computer e Equipped with two ports it is possible to plug Bluetooth interfaces an hub can be attached to install a large number of Bluetooth interfaces e The estimate price of these kind of routers floats between 70 and 100 de pending on factors like available memory or Central Processing Unit CPU clock speed The Hotspot prototype software developed to run in these routers was developed in Python with PyBlueZ 5 2 Evaluation objectives We have creat
2. remaining architectural components The focus of our study goes to the specification of a loosely coupled architecture oriented to user interactions and capable of turning these Bluetooth nodes on a new reusable system component that can be shared by multiple different applications To support such architecture this new Bluetooth nodes 1SWiigee http wiigee org is a Java based gesture recognition library for the Nintendo s Wii remote controller 29 are 1 designed with support for the most scenarios as possible 2 allowing their configuration at deployment time and 3 defining application independent protocols for communication with the other infrastructure components In order to achieve a fundamented design of such architecture a systematized analysis of the survey of this chapter will be presented on the following one 26 Chapter 3 Analysis for Hotspot design This chapter reports the analysis made over the survey of the previous chapter in the context of Bluetooth based interactions We have identified the relevance of a Bluetooth Hotspot system component In this analysis we are aiming at justifying and supporting on decisions for the design of the Bluetooth Hotspot component Firstly in section we systematize the types of interaction that may happen between this system component and the users grounded by the related work surveyed on the previous chapter Now with a new perspective we assume that the Applica
3. start is called when the extension is started An extension can be started in two situations 1 when the Hotspot system starts up or 2 when a new Bluetooth device is detected by the Scanner Module This method receives an argument with the Bluetooth interface assigned to the extension and an argument with the URL of the extension s configuration file The content of this file must be handled by the extension Section 3 2 3 details how extensions are handled by the Extensions Module e The second method newScan is called every time a new scan is per formed by the Scanner Module This method receives an argument with the Sighting associated with the scan e The third method stop is called when the extension is stopped by the Extensions Module This situation occurs when a new list of rules is loaded on the Hotspot and the extension is not referred in the list Only an instance per extension is launched a thread per instance While run ning an extension monopolizes a Bluetooth interface just for itself avoiding collisions with other Bluetooth tasks inside the Hotspot At the end the ex tension will be responsible to stop itself when appropriate using the method 50 stop and is strongly encouraged to do it as fast as possible in order to free the Bluetooth interface Scanner Extensions Interfaces Module Manager Manager register event new sean newscan sight1 sight request 8 slot
4. 3 its class hexadecimal value and 4 the list of its available services and associated channels If the second and fourth values are present also an extra field for each of them will also be 69 included containing the last date and time each one was retrieved When any of these fields is unknown they are automatically not included Example As an example we will assume a Hotspot called UbicompBluebox that is periodically scanning for devices The 17th scan started at 1h 32m 4s of April the Ist 2010 and took 48 seconds to retrieve all the data Three devices were found but only the name of the devices 22 22 22 22 22 22 and 33 33 33 33 33 33 were successfully retrieved Moreover only the services of the last one could be collected For this situation the resulting Sighting would be the next one scannerName UbicompBluebox scanBeginTime 2010 04 01 01 32 04 scanEndTime 2010 04 01 01 32 52 seqNumber 17 seenDevices device address 11 11 11 11 11 11 device address 22 22 22 22 22 22 name Mary Sea class 0x102 lastNameGet 2010 04 01 01 31 15 device address 33 33 33 33 33 33 name Nokia Michael class 0x102 services 2 Dial Up Networking 9 OBEX Object Push 10 SyncMLClient 11 OBEX File Transfer 12 Nokia OBEX PC Suite Services 13 SyncML DM Client 14 Nokia SyncML Server 15 Imaging 23 AVRCP Target 28 Hands Free Audio Gateway 10The channels and names of the services of the hypoth
5. 4 Main Controller The Hotspots work in a stand alone mode thanks to a list of rules which defines their behaviour For each Hotspot this list can be previously installed turning it on a standalone Hotspot or managed in real time by a OpenWrt www openwrt org is a Linux distribution optimized to run on embedded devices like Ethernet routers This distribution have the ability to run efficiently even with low resources like slow CPU e g 100MHz short memory e g 16MB of Random Access Memory RAM and tiny storage capacity e g 1MB central Main Controller Thus this component is responsible for managing the Hotspots by telling them how to behave If multiple Hotspots are deployed for example to cover a wide space they need to cooperate with each other otherwise their behaviours can be randomly erroneous e g when a file is sent by a Hotspot to a specific user device it should not be sent again by a second Hotspot that may also reach the device In this kind of scenarios the cooperation work between the Hotspots is responsibility of this Main Controllei The operation of this component is beyond the scope of this work Its architecture is not covered by this document Nevertheless the way it is integrated with the Bluetooth Hotspots and Applications is addressed The list of rules describes the Hotspots behaviour allowing them to be deployed and to run autonomously The list of rules is composed by a set o
6. Many works like use the Bluetooth Inquiry Protocol for proximity detection of users without any other objective than the detection itself The objective of such work is to collect the maximum amount of data concerning the presence of users in urban spaces like shoppings schools or car parks or to elaborate the notion of social context based on the analysis of interpersonal proximity data collected in a particular situation Bluetooth scanners are installed in different places of a city periodically scanning for the presence of devices and storing information about them Despite this paper is not specifying technical details about how this scanner is implemented and how the data is stored it does specifies which data is collected for each device 1 the hardware address which is unique and identical to an Ethernet address 2 the human readable name which is a name usually set by the user for easy identification of the device 3 the Bluetooth device clasg and 4 the list of services available on the device e g OBEX push modem fax Car traffic monitoring Device discovery is also used with other purposes like vehicle traffic monitoring for statistical purposes One in twenty vehicles have at least one Bluetooth enabled device inside it 43 a cell phone a GPS receiver an headset or even the car itself As seen in Figure with multiple Bluetooth scanners distributed along a high way or road it becomes possible to calculate the a
7. a single component the possibility of performing all the interactions that the actual Bluetooth interfaces are currently implementing in a dedicated way 1 application s developers become free from Bluetooth related issues and 2 phys ical spaces may become free from numerous Bluetooth devices when multiple applications share the same physical place Generally we call this component a Bluetooth Hotspot The final objective is to develop a fully capable prototype that runs on Linux enabled Ethernet routers To propose an integration model for Bluetooth user interaction systems The integration of our Hotspot with situated applications is based on a model designed to support the Bluetooth related interaction requirements of those ap plications This model is designed in order to serve multiple applications that may coexist on the same physical space in the most optimized way possible 1 2 System overview The environment that evolves our Bluetooth Hotspots is composed by four essential entities illustrated in Figure They are 1 the set of user s Bluetooth devices 2 applications that expect some kind of user centered interaction using the Bluetooth technology 3 Bluetooth Hotspots and 4 a Main Controller that manages the Hotspots User s Bluetooth devices Any kind of device equipped with Bluetooth can be in cluded on this set although cellphones or Personal Digital Assistants PDAS are 3 MM main controle feed
8. each of these types of interaction will be detailed in the next four sections The last two types 4 and 5 are grouped in the same sub section 3 1 1 Getting the address and name of a device Probably the most important type of interaction as it is the most common used in all scenarios is the detection of a Bluetooth device All the applications that require to know the present devices have to periodically scan the environment This 28 process may include a phase for obtaining the devices name or simply their hardware address In some cases obtaining the available services e g Object Push Dial Up Networking Hands Free Audio Gateway of each device is also required as for example in the case of file transfers see next sub sections We have identified the common phases during this type of interaction 1 In the configuration phase the Bluetooth Hotspot is configured for periodically scanning for present devices 2 In the second phase the Bluetooth Hotspot is responsible for getting the address and Bluetooth names of present devices and finally 3 In the third phase the Bluetooth Hotspot is responsible for sending device information to the applications This scenario is illustrated in the sequence diagram of Figure 2580 20598 cama ES Device Hotspot Application behaviour device is seen y description get name l YA 3 sightings list l l l Figure 3 1 Sequence diagram illustra
9. identification of the task and extra related information Because multiple applications may be sharing the same Hotspot from now on we will assume the controller as an autonomous component focused on controlling the Hotspot As this component controls the Hotspot we identify it as The Main Controller or simply The Controller Device Sightings Different systems surveyed are based in different kinds of Bluetooth interaction with users However almost all of them refer to the existence of a device scanner a com ponent that periodically searches for the present Bluetooth devices and then collects more or less information about them depending on the objective of the applications This information can be as simple as the device hardware address or more complex as the human readable name the class type of device or the available Bluetooth services on each device For each scan the list of present devices is referred in some articles as a Sighting 14 A Sighting can be locally stored or sent to a remote site over the network 27 In this case this action is usually performed through the serialization of an X ML file that contains all the information collected about the discovered devices Download and upload of files from to devices Scenarios of content delivery or content pull deal with files which are sent or received to from user s devices These files can be locally stored 9 inside the Hotspot or remo
10. receive feedback logs about the execution of the desired tasks The protocol is formed by two parts 1 The first part consists on the specification of an URL associated with each Hotspot Configuration rule that identifies the application resource to be updated with the respective feedback log 2 The second part consist on the specification of the feedback message The feedback message is delivered over an HTTP POST on the specified Feedback logs may be delivered using two different methods 1 rule by rule using a different location for each defined rule or 2 in a unique that holds all the tasks performed by the Hotspot 45 The first method is useful to deliver logs to different applications that share the same Hotspot The second method is useful to deliver feedback logs to the Main Controller if it is present In terms of configuration the difference between one method and the other is in the Hotspot Configuration Rules the first method uses an argument rule by rule while the second method uses a specific rule for this end Refer to Section for a more extensive explanation Feedback message The feedback message is an YAMLfile Its format is composed by three values status message and rule e The first value status contains a number that identifies the status error If equals zero 0 it means that the task was successfully performed If it differs from zero it means that an error has occurred
11. which may be integrated in client applications offering different services for that space Its function is to manage Bluetooth interactions between mobile devices and client appli cations The processes of integration must as much as possible existent interaction requirements in order to minimize any changes to existing interaction models We will now enumerate the most relevant issues for the process of integration 33 Hotspot s behaviour description In order to achieve the correct interactions at the right moment accordingly to the applications requirements applications need to somehow configure their Bluetooth interfaces In 14 Bluetooth components are pre configured to send the list of present devices to a remote server on each scan In 9 a list of rules is used to describe 1 when and 2 what to deliver 3 to which devices An extended version of this type of rules must describe the behaviour of the Hotspot to achieve those interactions identified as being the most relevant refer to Section 3 1 If we replace current Bluetooth interfaces with our Bluetooth Hotspot those rules will need to be described and uploaded to the Hotspot by applications or by some other component acting as a controller This controller must configure the Hotspot with such rules but also retrieve reports generated by the Hotspot to be up to date with every task performed by it These reports include the time when a task was performed an
12. SCHIEK A PENN A FRASER LL D AND JONES T Instrumenting the city Developing methods for observing and understanding the digital cityscape In UbiComp 2006 Ubiquitous Com puting P Dourish and A Friday Eds vol 4206 of Lecture Notes in Computer Science Springer Berlin Heidelberg 2006 pp 315 332 34 PETERSON B S BALDWIN R O AND KHAROUFEH J P Bluetooth inquiry time characterization and selection IEEE Transactions on Mobile Computing 5 9 2006 1173 1187 35 PIETIL INEN A K OLIVER E LEBRUN J VARGHESE G AND DIOT es C Cityware Urban computing to bridge online and real world social networks In Applications Technologies Architectures and Protocols for Computer Commu nication 2009 86 36 PODNAR I HAUSWIRT M AND JAZAYERI M Mobile push Delivering content to mobile users In in Proceedings of the International Workshop on Dis tributed Event Based Systems ICDCS DEBS 02 2002 IEEE Computer Society pp 963 970 37 a RASHID O COULTON P AND EDWARDS R Providing location based infor mation advertising for existing mobile phone users Personal Ubiquitous Comput ing 12 1 2008 3 10 38 SANCHEZ J M CANO J C CALAFATE C T AND MANZONI P Bluemall a bluetooth based advertisement system for commercial areas In PM2HW2N 08 Proceedings of the 3nd ACM workshop on Performance moni toring and measurement of heterogeneous wi
13. Using A Bluetooth for Situated Interaction in Public Displays IEEE Pervasive Computing 7 4 2008 52 57 So 28 KINDBERG T AND Fox A System software for ubiquitous computing IEEE Pervasive Computing 1 January 2002 70 81 29 _ LEBRUN J AND CHUAH C N Bluetooth content distribution stations on public transit In MobiShare 06 Proceedings of the 1st international workshop on Decentralized resource sharing in mobile computing and networking New York NY USA 2006 ACM pp 63 65 30 MAHATO H KERN D HOLLEIS P AND SCHMIDT A Implicit person a alization of public environments using bluetooth In CHI 08 extended abstracts on Human factors in computing systems New York NY USA 2008 CHI 08 ACM pp 3093 3098 31 a MCCARTHY J F CONGLETON B AND HARPER F M The context content amp community collage sharing personal digital media in the physical workplace In Proceedings of the 2008 ACM conference on Computer supported cooperative work New York NY USA 2008 CSCW 08 ACM pp 97 106 32 es NICOLAI T YONEKI E BEHRENS N AND KENN H Exploring social con text with the wireless rope In On the Move to Meaningful Internet Systems 2006 OTM 2006 Workshops R Meersman Z Tari and P Herrero Eds vol 4277 of Lecture Notes in Computer Science Springer Berlin Heidelberg 2006 pp 874 883 33 ONEILL E KoSTAKOS V KINDBERG T
14. a set of modules called the Bluetooth Modules that execute the most relevant Bluetooth interactions A coherent integration means that these Modules 1 respect the available bandwidth for each Bluetooth interface using the Interfaces Manager that decides what Bluetooth interface is to be assigned 2 register the appropriated event on the Scheduler for each Bluetooth task to be performed and 3 free the Bluetooth usage slots after all the Bluetooth interactions are performed The Hotspot includes three modules that natively offer three types of Bluetooth interactions 1 the OBEX Sender Module 2 the OBEX Receiver Module and 3 the The reason to use 8 slots comes from a Bluetooth specification that limits a Bluetooth interface to use ate last 8 connections or 8 devices at the same time I 8 The decision of what interactions to include was based on the related work survey of Chapter and is justified in the analysis survey of Chapter 3 92 Scanner Module There is a fourth module with an extension mechanism that allows to extend the Hotspot s functionalities OBEX Sender Module This module is dedicated to the delivery of files over Blue tooth to other devices As depicted in Figure 4 5 when it is used by the Scheduler a Bluetooth interface is requested to the Interfaces Manager using one usage slot to send the file The file to be sent is downloaded from its using the Re sources Manager After downloaded the file is then
15. design of the Bluetooth Hotspot we are proposing The identification and study of these patterns will also justify the design of a modular architecture for this component Based on the research we grouped those kinds of user interactions in five main sets 1 simply scan for the present devices 2 get the name of user s devices 3 send or receive a file to from user s devices 4 gesture recognition using the Nintendo s Wiimote accelerometer and 5 connection based interactions Due to its relevance and based on the analysis of Chapter 3 most of these inter actions will be natively integrated on the architecture of the Bluetooth Hotspot that is proposed in this document Many other interactions could be included like print or audio over Bluetooth but they were excluded as they does not show currently to be relevant for the context of Smart Spaces and Pervasive Computing A section for each kind of interaction we have studied is presented below Each section briefly introduces how that kind of interaction is often used and then present some of the most relevant works studies systems and applications for our research For each of them we will detail as much as possible not only the interactions over Bluetooth between the user and the infrastructure but also the main system components and the most relevant issues about their system architectures 2 1 Device scan interaction The Bluetooth Inquiry Protocol enables a device to discover
16. for situated interaction in ubiq uitous environments Master s thesis Departamento de Sistemas de Informac o Universidade do Minho 2009 DAVIES N FRIDAY A NEWMAN P RUTLIDGE S AND STORZ O Us ing bluetooth device names to support interaction in smart environments In MobiSys 09 2009 pp 151 164 EAGLE N AND PENTLAND A Social serendipity Mobilizing social software IEEE Pervasive Computing 4 April 2005 28 34 EAGLE N AND SANDY PENTLAND A Reality mining sensing complex social systems Personal Ubiquitous Comput 10 March 2006 255 268 FIELDING R T AND TAYLOR R N Principled design of the modern web architecture ACM Trans Internet Technol 2 May 2002 115 150 FITZ WALTER Z JONES S AND TJONDRONEGORO D Detecting gesture force peaks for intuitive interaction In TE 08 Proceedings of the 5th Australasian Conference on Interactive Entertainment New York NY USA 2008 ACM pp 1 8 34 119 FONSECA R AND SIM ES A Alternativas ao XML YAML e JSON In XATA 2007 5 Confer ncia Nacional em XML Aplicacoes e Tecnologias Aplicadas February 2007 J C Ramalho J C Lopes and L Carr co Eds pp 33 46 20 FRESNEDO O IGLESIA D I AND ESCUDERO C J Bluetooth inquiry procedure optimization and influence of the number of devices In CSN 07 Proceedings of the Sixth IASTED International Conference on Communication Systems and Networks Anaheim CA US
17. funcionando como uma prova de concceito desta com ponente IV Contents 1 Introduction 1 1 Objectives 1 2 System overview 1 3 Methodology 1 4 Structure of the dissertation 0 0 00 pe ee ee en 2 Related work 2 1 Device scan interaction EI iaa aa AAA 2 3 1 Content delivery applications TESEI TEA 2 5 Wiimote based interaction 2 6 Discussion 3 Analysis for Hotspot design 3 1 User interaction patterns 3 1 1 3 2 1 Getting the address and name of a device re ee ee ee eee O nu Integration 3 2 2 State management 3 2 3 Extensibility 3 3 Bluetooth related scalability issues 2 20 20 0000 08 3 9 1 Scanning frequency Q Ov Co N E co 00 10 15 15 21 2i 23 29 3 3 2 Multiple Bluetooth interfaces 0 4 Design for Hotspot implementation 4 1 System components 4 2 Components integration 2 a a a a ee 4 2 1 The Hotspot behaviour 20048 4 2 2 Hotspot sharing e eke eed ewe REY EEE ER A E ee ee RASA aa 4 2 4 Feedback protocol 2 0 0 0 0 0 ee iio iran sees del CC saa owe aw eRe we AAA TRE 4 3 3 Bluetooth Modules a 4 4 _Rules s structure kbs ee Rae ars AA 4 4 1 Enabling device scans a eee eee ass A aa aes oir rare a ra ans 4 5 Sighting s structure 5 Evaluation 5 1 Evaluation environment
18. in the environment such as Wi Fi spots GPS receivers Bluetooth components RFID readers mobile phones or cameras Bluetooth is a short range wireless technology which is present in a wide number of handheld devices and requires zero configuration By this mean it becomes a powerful tool to be used for interaction with physical environments and consequently has been adopted by different applications and systems as a privileged interaction technology Currently those are implementing their own Bluetooth com ponents that perform application specific tasks like getting information about user devices sending or receiving files In this dissertation we argue that Bluetooth components may be managed as in teraction resources in the physical space which can be shared and reused by different third party applications and systems This situation would free application developers from Bluetooth management related issues and would allow them to focus in applica tion objectives Additionally our approach may also contribute for the sustainability of the Pervasive Computing industry from an environmental perspective as it will enable sharing and reusing of physical resources and potentially reducing the number of local computing devices In this work we studied relevant projects and applications for Pervasive Computing and Smart Spaces that use Bluetooth an interaction mean Common characteristics of these projects are identified an important step t
19. of feed back log reports 3 the management of Internet resources such as files and 4 the management of available bandwidth at each installed Bluetooth interface Hotspot Managers functionality is used by the Scheduler component Bluetooth Modules These components perform Bluetooth specific interactions 1 device scannings to obtain the list of present devices device names and their available services 2 sending files to devices and 3 receiving files from devices Each Module is responsible for one type of interaction but a special fourth Mod ule is dedicated to the management of Bluetooth Extensions Extensions Extensions are software components that execute application specific tasks such as Wiimote controllers interactions or other Bluetooth profiles s in teractions An extension is intended to be developed along with an external application that uses a Hotspot This specific interaction modules are integrated with external applications using the same model defined for Bluetooth Modules described above Extensions are installed on the Hotspot before its operation and thus they can be referenced at the Hotspot Configuration Rules An extension can work in two modes 1 always running started along with the startup of the Hotspot This allows the extension to be listening to new connections that are started from devices to the Hotspot or 2 be instantiated started just when a device or a group of devices i
20. on the Scheduler The new file of rules is appended to the event as an argument When this event is registered the Scheduler starts or stop the Modules in question accordingly to the rules Logs Manager The logs manager is the component responsible to build the Hotspot s feedback logs this mechanism of feedback for application is described in Section 4 2 4 Every time an event is registered on the Scheduler a log entry is created in the Logs Manager When an action is performed by the Scheduler a log entry is also created Resources Manager This component manages Internet resources like files All the other Managers Modules and the Scheduler s actions use this manager to access external resources from the web With this manager files can be downloaded The Main Controller uploads the rules files to the Hotspot s HTTP server This server is provided by the Resources Manager which is listening for the input of new files Open Wrt Linux distribution uses a mechanism called UCI that allows the configuration of single values associated to identification variables This variables are centralized on the system and can later be consulted by any application running on the system In this case the period of time in seconds between each download is included on the second line of the same file ol and uploaded from to applications File exchanges are performed over H T TP requests and each resource is identifi
21. should be set in a magnitude of seconds around 30 seconds A greater value would result in a poor usability for the user We could also conclude that the inquiry phase of the name of each device may take too much time when a large number of devices is present his situation was predicted during the design phase section issue referred in Section 3 3 1 where a user waits for a feedback twice the expected time This issue proves that the support for multiple Bluetooth interfaces is a strong requirement in order to achieve concurrent tasks e g scanning with a device and getting device names with another This leaded us to the implementation of the fast mode scanning described in Section 4 3 3 The collected information about present devices hardware address name class and services was useful not only for our research but also for the InstantPlaces inves tigation because is allows to validate 1 the Sighting s structure and 2 the differences Facebook http www facebook com 10 An entire full cycle scan includes 1 searching for the present devices 2 retrieving its names and 3 retrieving the available services on each one 12 between silent scanning and situations where users known that their devices were being searched or where they could suggest content to show on the public displays using a predefined tag on their device s names For the studied cases of deployments the time between
22. will be needed to obtain the name of each device In the example of Figure a the scanner detects 7 devices but it only obtains the name of 5 of them The process of getting the name of the other two devices marked with an asterisk in Figure times out A device Sighting refer to Section with the list of all detected devices may only be generated after 20 seconds time 20 e In the second situation b independently of the time needed to process the whole scanning process this is aborted when the maximum scanning time is reached even if the process is not complete In Figure b if we consider again the situation where 7 devices are detected a device Sighting that contains the list of all devices and the names of three of them is generated after 10 seconds time 10 The name retrieval of the fourth device marked with an asterisk is canceled and a new scan is immediately started Example As an example we will assume a router that is constantly scanning for Bluetooth devices and then retrieving the Bluetooth name and available services of each one with a full cycle scan period of 20 seconds in this case for a full cycle scan we understand the whole process of inquiry name retrieval services retrieval This means that a new scan should be performed at least every 20 seconds However as the inquiry process takes around 10 seconds 20 the scanner will have only 10 seconds more to retrieve the names and g
23. 0 ee ee ek ks 9 2 Evaluation Objectives a a a a a 5 3 Real scenarios deploymentst e 5 3 1 First phase 5 3 2 Second phase 5 3 3 Third phase 6 Conclusions Bibliography Acronyms List vi 41 Al 43 43 44 45 45 AY 48 50 52 IS 50 60 60 6l 63 64 69 68 68 69 71 71 13 16 80 87 Chapter 1 Introduction Pervasive Computing is as a new paradigm for computing systems where computation is spread through everyday objects able to communicate with each others and the users 39 One of the main characteristics and challenges of Pervasive Computing systems is the physical virtual integration the increasingly pervasive presence of all sorts of sensors such as Wi Fi spots GPS receivers Bluetooth components Radio Frequency IDentification RFID readers mobile phones or cameras in our physical world The capability to network those sensors and infer information from their data is greatly expanding the ability of the virtual world to perceive the physical world and react accordingly The existence of all sorts of those sensors in our physical world have promoted the emergence of different trends in Pervasive Computing Context aware computing was the main trend deriving from this characteristic in the sense that context aware computing is a field on which software applications behaviour is defined by contextual information Such context aware software adapts according to the location of us
24. 1 the architecture The relationship between a Hotspot and specific applications can be simple and easy to be implemented if both of them are deployed together for the same end How ever if a Hotspot is already deployed new applications do not recognize the presence and the availability of Hotspot s automatically A mechanism to handle the regis tration of Hotspots is important in the future This way further applications may consult this service to discover the available Hotspots on the specific space they want to operate This is the typical service that can be integrated in the Main Controller The source code of the Hotspot prototype developed during this dissertation was published as an open source project at Source Forge repository https sourceforge net p bluebox hotspot Providing the source code it may empower not only this project but many other projects in the area of Pervasive Computing Along with the source code we provide a package to be included on OpenWrt s software repository to ease installations on new systems using its package management system opkg Conclusion Overall we showed that there is a space for a Bluetooth system component that can be easily shared and reused We have described the main key design issues for such component and its system integration We have deployed our component within dif ferent systems It proved to have an acceptable performance in most of the predicted scenarios Addi
25. A 2007 ACTA Press pp 205 209 21 HARTER A HOPPER A STEGGLES P WARD A AND WEBSTER P The anatomy of a context aware application Wireless Networks 8 March 2002 187 197 22 HELAL S MANN W EL ZABADANI H KING J KADDOURA Y AND JANSEN E The gator tech smart house A programmable pervasive space Com puter 38 March 2005 50 60 23 JAYARAMAN P P ZASLAVSKY A AND DELSING J On the fly situation composition within smart spaces In Proceedings of the 9th International Con ference on Smart Spaces and Next Generation Wired Wireless Networking and Second Conference on Smart Spaces Berlin Heidelberg 2009 NEW2AN 09 and ruSMART 09 Springer Verlag pp 52 65 24 Li JOHANSON B FOX A AND WINOGRAD T The interactive workspaces project Experiences with ubiquitous computing rooms IEEE Pervasive Comput ing 1 April 2002 67 74 25 JOHANSSON P KAZANTZIDIS M KAPOOR R AND GERLA M Bluetooth an Enabler for Personal Area Networking In IEEE Network Magazine Wireless Personal Area Network 2001 vol 15 pp 28 37 26 JOSE R AND BERNARDO F Extended bluetooth naming for empowered pres ence and situated interaction with public displays In 3rd Symposium of Ubiquitous Computing and Ambient Intelligence 2008 vol 51 of Advances in Soft Computing Springer Berlin Heidelberg 2009 pp 57 65 27 Jos R OTERO N IZADI S AND HARPER R Instant Places
26. Bluetooth connections established However there is a limitation that we must care about the Bluetooth specification limits the number of connections with other devices to 8 con nections 1 This means that if we want to keep more than 8 connections at the same time the Hotspot will need to handle more than one Bluetooth interface Using more than one interface is also extremely important in scenarios of real time interaction where device scans must me performed simultaneously with other Bluetooth tasks like we have described in the section above Having multiple Bluetooth interfaces in the same Hotspot raises a management problem The load over all available interfaces must be equally distributed between all of them When a Bluetooth task is going to be performed the Hotspot checks which of the interfaces have the minimum number of connections established and assigns it to that task Because of the Bluetooth stack limitation of 8 connections the Hotspot must be able of tracking how many of them are being used on each interface The number of interfaces needed when a Hotspot is deployed will always depend on the situation where the Hotspot operate The number of devices is increased according to the needs offering scalability until the limit of 15 devices refer to OpenProximity in Section 2 3 1 40 Chapter 4 Design for Hotspot implementation In this chapter we present the Bluetooth Hotspot architecture This chapter also ex
27. Bluetooth Hotspots for Smart Spaces Interaction Mestrado de Engenharia Informatica Universidade do Minho Advisor Prof Helena Cristina Rodrigues Miguel Craveiro Martins de Almeida October 2011 Acknowledgements I express my deep gratitude to Professor Helena Cristina Rodrigues for her guidance valuable scientific support helpful advises and for her constant patience I also would like to thank other members of the Ubicomp team at Universidade do Minho namely Prof Rui Jos Arlindo Santos and Bruno Silva for their support which was very important in all the steps of this dissertation I am thankful to Pedro Farinha for his precious help in part of this work particularly in what concerns the development of the Wiimote Extension s prototype I wish to thank Mariana Pulido and my friends Afonso Arriaga Mario Pinhal and my brother Nuno for all their support enthusiasm and friendship and for helping me revising this document Thanks are still due to Departamento de Sistemas de Informacao of Universidade do Minho for all facilities Finally I would like to thank my parents and brothers for all their familiar permanent support Without it this dissertation would not be possible Abstract In scientific literature and industry mainly in the area of Pervasive Computing and Smart Spaces a variety of applications and systems may be found which are based on both explicit and implicit user interactions with physical resources
28. Bluetooth interface can perform simultaneously without loss of per formance Different operations take different times to perform For example 1 scan 2 scan get device name 3 scan get device services 4 scan get device names get device services delivering receiving files or 5 other com binations of Bluetooth operations and interactions With these deployments we wanted to measure performance times in real scenarios In some contexts some operations may take too much time if they run sequentially that it strongly dis courages the usage of a single interface In that situations the usage of multiple interfaces should be required 10 5 3 Real scenarios deployments The validation of the prototypes was done in two different phases e in a first phase we have tested the Hotspot s Modules independently without being integrated with the whole Hotspot system and e in a second we have tested the Hotspot s Modules all together on the same Hotspot integrated with all the other components In both phases the validation was performed using prototypes of the designed system on two projects running at our departmentf Instant Places and Any WherePlaces both oriented to the area of Pervasive Computing and Smart Spaces Both phases were performed with our prototypes running on ASUS WL500gP v28 routers equipped with the Linux distribution OpenWrt 8 09 2 and a minimal version of Python 2 5 The choice of older v
29. I Application Programming Interface SMS Short Message Service RFID Radio Frequency IDentification MAC Media Access Control PDA Personal Digital Assistant IP Internet Protocol LED light emitting Diode ID Identification Number NAT Network Address Translation RAM Random Access Memory TCP Transmission Control Protocol RPC Remote Procedure Call POS Point of Sale GPRS General Packet Radio Service SDK Software Development Kit SSH Secure Shell GUI Graphical User Interface CPU Central Processing Unit VPN Virtual Private Network AP Access Point BEN Bluetooth Extended Naming UCI Unified Configuration Interface OBEX OBject EXchange PAN Personal Area Network BNEP Bluetooth Network Encapsulation Protocol HID Human Interface Device RFCOMM RFCOMM Serial Cable Emulation Protocol L2CAP Logical Link Control and Adaptation Protocol SDP Service Discovery Protocol HCI Host Controller Interface SPP Serial Port Profile SPP over IP Serial Port Profile over IP
30. L format exactly as it is used by Hotspots and applications 5 is twofold First we intend to survey related projects in order to describe the different requirements and architectural approaches for supporting Bluetooth in teractions Then we intend to identify common characteristics across different scenarios and systematize the main types of Bluetooth interactions This is the basis for defining the main interactions between the whole group of system com ponents such as the Bluetooth Hotspot the client applications the web resources and the controller Proof of concept prototypes In a second phase we have deployed basic prototypes of the Bluetooth Hotspot in order to evaluate technical decisions that have been made such as the choice of the target hardware and the development language The prototypes were deployed together with on running projects that already use Bluetooth interactions This evaluation is done in the context of the on running projects at Departamento de Sistemas de Informacad such as Instant Places Fully capable prototype for strong validation In a third phase a more com plete and robust prototype was developed and deployed see Chapter 5 to vali date not only the whole designed architecture but also the proposed integration model with client applications Several Bluetooth Hotspots were deployed and configured in multiple scenarios re used for different types of interactions and shared by differ
31. When multiple applications share the same space with users those interfaces could be replaced by a common one The interface would be shared between applications and would be reused by future applications that use the space If we make an analogy with the term Wi Fi Hotspot used for Wi Fi A P that are publicly available and because this component becomes available to the present devices on a space we will call it from this moment on a Bluetooth Hotspot The Bluetooth Hotspot as a new Bluetooth component In this chapter we will instantiate previous user interaction patterns in our high level architecture The main components of our architecture are 1 the users devices 2 the Bluetooth Hotspot and 3 the applications that use the Hotspot as a Bluetooth resource During this analysis original characteristics of the Bluetooth components will be preserved New characteristics are only introduced from a management point of view those we understand to be essential for Hotspot sharing and reusability This step turns on to be the most important step in the design of the Hotspot architecture later presented in Chapter We have grouped Bluetooth interactions in four different types 1 obtaining the address and name of present devices 2 sending a file to a device 3 receiving a file from a device 4 to establish a connection with a device Assuming that the original Bluetooth components are now replaced by the Blue tooth Hotspot
32. WiiMote Figure 5 2 A screenshot of our prototype of an application that integrates with the Hotspot and identifies the data inputs of Wiimotes connected to the Bluetooth Hotspot SNintendo Company Limited http www nintendo com Y Wiimote Extension This extension turns the Hotspot on a bridge between the Bluetooth Nintendo s Wi imotes and a remote application that recognizes its gestures 40 For each discovered Wiimote the extension establishes two connections in both directions 1 a Bluetooth serial connection with the Wiimote and 2 a socket connection with the application that analyzes gestures and pressed buttons After having established these two connec tions the extension redirects to the application all the data received from the Wiimote stream This stream includes the x y z values of the Wiimote accelerometer the x y z coordinates of the location of the Wiimote and the list of buttons that are being pressed In our prototype the application is a Java program that receives the data from that connection and illustrates the Wiimote status at the screen just for validation A screenshot of this application is seen in Figure 5 2 Our aim is to interpret the gestures and provide the results to an that can be used by other applications with the objective of deploying a real scenario to validate this model A possible scenario is an interactive presentation at a museum or an artistic installation were use
33. a a shared interactive display supporting social temporal and spatial awareness in surgery In Proceedings of the 2006 20th anniversary conference on Computer supported cooperative work New York NY USA 2006 CSCW 06 ACM pp 109 118 8 BAUMANN S JUNG B BASSOLI A AND WISNIOWSKI M BluetunA let your neighbour know what music you like In CHI 07 extended abstracts on Human factors in computing systems New York NY USA 2007 CHI EA 07 ACM pp 1941 1946 83 9 CAMACHO T A D Proximity sensing and context aware content dissemination 11 12 14 15 16 A A a Master s thesis Department of Mathematics and Engineering of the University of Madeira 2009 CANO J C MANZONI P AND Ton C K Ubiqmuseum A bluetooth and java based context aware system for ubiquitous computing Wireless Personal Communications 38 2006 187 202 CHATSCHIK B An overview of the bluetooth wireless technology Communica tions Magazine IEEE 39 12 December 2001 86 94 CHEVERST K Dix A FITTON D KRAY C ROUNCEFIELD M SAS C SASLIS LAGOUDAKIS G AND SHERIDAN J G Exploring bluetooth based mobile phone interaction with the hermes photo display In MobileHCI 05 Pro ceedings of the 7th international conference on Human computer interaction with mobile devices services New York NY USA 2005 ACM pp 47 54 DA CRUZ BERNARDO J F Bluetooth naming
34. aching Internet resources like files sending resources or managing the concurrency of the Hotspots Bluetooth interfaces USB dongles Rules Manager This is the component that manages the Hotspot Configuration Rules refer to Section for details about this rules This manager interprets 50 a file of rules that is loaded using one of the methods below referred When loaded the current rules can be requested by the Scheduler every time it needs them There are three possible ways to load a new file with a list of rules on the Hotspot e statically defined on a local and static file e through the remote Main Controller at any time in the case for scenarios where the list needs to be constantly updated e by periodically downloading it from a remote URL in the case for scenarios where the Hotspot does not have a public IP address If the Hotspot software is running on the OpenWrt operating system inside Ethernet routers the configuration of which method is to be used is done using the OpenWrt s configuration mechanism called Unified Configuration Interface This configuration includes the of the rules file The can be a local path for the first method or a remote location for the third method If the Hotspot software is running on another operating system the same configuration is done on a static text file Every time a new rules file is loaded the Rules Manager registers an event newrules
35. application e g received file sent file error receiving or error sending a file 3 1 4 Establishing a generic connection We have described in Section and other Bluetooth based interaction patterns which mainly rely on the establishment of a generic connection between the mobile device and the application On top of such connection application specific interaction patterns are implemented by both ends of the connection The establishment of a connection may be either initiated by the mobile device or the Hotspot on behalf of the application 3 En Hotspot Application y behaviour description connection Figure 3 4 Sequence diagram illustrating interactions for a Bluetooth Hotspot that establishes a connection with a device Figure depicts the establishment of a socket connection over an connection between the Hotspot on behalf of an application based on Wiimote inter actions This scenario was described in Section and will be used as a prototype in the validation phase The establishment of the connection will follow the following steps 1 Applications 31 configure the Hotspot to scan for present devices and to establish a con nection 2 For every scanned device the Hotspot inquires the device for the available services 3 If the Wiimote service Nintendo RVL CNT 01 is available the Hotspot establishes a connection with the device and 4 a socket connection with the application 5 Once the connectio
36. are entities 1 client mobile devices 2 BlueMall Access Points AP and 3 a central server This server is responsible for the management of Bluetooth APp maintaining the state and context of every action of the whole system APE have the ability for 1 constantly searching for Bluetooth devices and 2 delivering files to those devices Figure 2 5 An abstraction of Bluemall architecture for content delivery Image adapted from 38 As represented in Figure BlueMall are configured by the server using a XML file containing variables like the AP location time elapsed to consider a client s visit to be a new visit server s address and the amount of time to ignore a device until it is considered as a new visit After configured the starts scanning and delivers to the server the list of device sightings on each scan Every time a device is seen identified by its hardware address the server s database is updated also registering if the OBEX Object Push service is available Knowing such information speeds up further scans since there is no need to ask the device for the service availability again To avoid flooding users with files which can be very negative if it leads the user to turn off his device BlueMall takes care of what information is sent to whom and 16 when The system also supports a white list of devices not interested in receiving files intended to be filled with the addresses
37. ation With this application students are able to interact with the lecturer s server software using a socket over a Bluetooth connection The paper also describes the possibility to use a generic Bluetooth A P The paper does not detail what is in fact a generic Bluetooth AP but it describes it as a component which maintains a connection with the clients that may be deployed on a class room without the need of a complex infrastructure or a dedicated computer The only requirement is a Ethernet connection or wireless link to connect the Bluetooth AP to the Internet BluetunA The Human Connectedness Research Group at MIT has developed tunA an application that runs on PDAE and allows users to share music with other nearby users that run the same application on their PDA The application uses a Wi Fi ad hoc network to reach the nearby tunA s users Each one can see the other s profiles l6 Human Connectedness Research Group http web media mit edu stefan hc 22 consults their playlists and listen what they are listening over a peer to peer audio streaming Stephan Baumann et al developed BluetunA 8 an application identical to tunA that uses Bluetooth to reach the other users instead Wi Fi ad hoc networks Despite the application being designed to run on handheld devices and to connect to other devices the paper briefly introduces the concept of a BluetunA Hotspot under devel opment The idea
38. att 10 Bluetooth detector 2 miles Bluetooth detector travel time 2 32 minutes speed 47 4 MPH time 8 06 58 AM Figure 2 2 Multiple Bluetooth scanners along a road to determine the average speed of cars with a Bluetooth device inside it Image adapted from 143 obtained and shown on the screen for the user to select which one to connect Some works in the area of Pervasive Computing use this kind of inter action not only for proximity sensing but also to obtain information about users The idea is to use the device name to suggest information on the context of some activity The user just needs to set the name of its device to some text that is recognized by the system With this method the user can deliver a simple text to the system without installing any kind of application turning on a easy to use and cross platform method Name abbreviation A problem inherent to this method is the limited space available of the device name Despite of the Bluetooth specification limit of 248 bytes with UTF 8 encoding for the device name 1 most of the device brands strict to their own limit sometimes below 32 characters This turns abbreviation almost an obligation 14 This problem was a motivation for the creation of Bluetooth Extended Naming which describes a method and its implementation to turn Bluetooth device names into a command line interface for interactions with near systems They propose a synta
39. back interactions gt context and resources gt 4 Figure 1 1 An abstraction of the main components of the system designed the most usual ones These devices act as a user s terminal which exchanges information with the rest of the infrastructure Applications Applications are pieces of software that perform user centered tasks based on some kind of interaction with users over Bluetooth technology Despite usually running on a computer the physical location where these applications run is irrelevant for the whole system if they can be reachable on an Internet Protocol IP network A typical application is the one running on a public display that shows useful information such as news videos or photos and expects the input from users with suggestions of content In this case the public screen acts as an output device for the application while the user Bluetooth device acts as an input device Bluetooth Hotspots Hotspots are small boxes which act as a bridge between user devices and the applications In order to interact with users these Hotspots perform Bluetooth tasks such as detecting the user s devices presence retrieving their device s name receiving or sending files among other similar tasks These boxes are equipped with embedded devices Ethernet routers running OpenWrt Linu q which run the software that was developed based on the architecture proposed in Chapter
40. d between users and the Hotspot and not with the application A typical situation is for sharing an Internet connection with a device over BNEP to establish a PAN connection like Bluegiga does refer to Section 2 3 1 Figure 3 5 b illustrates this type of scenarios where 1 The Hotspot should be configured to accept connections 2 When a device tries to establish a connection with the Hotspot 3 a new connection must be established between the Hotspot and the device The application should only be informed about the result of this action if suc ceeded or failed but does not receive any content from the device 32 q En Hotspot Application behaviour description start connection connection q En avice Hotspot Application behaviour O i description start connection report l l error ok Figure 3 5 Sequence diagram illustrating the existing interactions for a Bluetooth Hotspot that accepts incoming connections over RFCOMME a managed by an application or b managed by the Hotspot 3 2 Key design issues In this section we will enumerate and describe the main key design issues for the design and development of the Bluetooth Hotspot system component Our work is based on the analysis of the main interaction patterns described in the previous sections 3 2 1 Integration The Bluetooth Hotspot component should be designed as a new space resource
41. d with Bluetooth technology to communicate with other devices four light emitting Diodes LED a vibrator a small speaker and two sensors that improve the user interaction 1 An Infrared sensor enables the controller to perceive its location relative to two IR emitting diodes installed above or bellow the television and 2 an accelerometer that measure peaks of movement on three axes x y 2Z Nintendo Co Ltd http www nintendo com 23 The Wiimote is represented in Figure 2 8 providing the basis for computer gesture input and recognition The recognition of well defined gestures like squares circles rolls or other types of similar movements makes the Wiimote a powerful tool for many applications that support human interaction based on gestures 40 Roll Z Figure 2 8 The three axes and three rotation movements that can be detected by the Wiimote Image source Osculator http www osculator net When a Wiimote is turned on it enters on the Inquiry Scan State which means that the device can be detected by other devices situation already described in Section 2 1 At this moment the controller also announces the service Nintendo RVL CNT 01 and starts listening for new connections At the same time the Wii console which is periodically searching for Wiimotes devices with the name Nintendo RVL CNT 01 will find it and establish a serial emulated link with it using the protocol From this mome
42. e Hotspot s system architecture where a main application or a Main Controller manages the Hotspot As seen in the figure the main point of control or master may be 1 one of the sharing applications or 2 a dedicated service that we denominate as The Main l Typically this happens when the Hotspot is behind a firewall or installed on network with Network Address Translation NAT 44 Controller Despite our work is not focusing on the design and implementation of this component we refer their characteristics and assume it is present in the architecture 4 2 3 Multiple Hotspots In many scenarios a one to one association between an application and a Hotspot will be sufficient This is true when the application s space may be covered by only one Hotspot For example an application running on a public display which interacts with nearby users However there will be other scenarios where an application or the Main Controller if it exists will have to manage multiple Hotspots as analyzed in Section This situation is depicted in Figure 4 3 Figure 4 3 Representation of multiple Hotspots reused by the same application The coordination of context between those two Hotspot is performed by the Main Controller 4 2 4 Feedback protocol The feedback protocol was designed to address fault tolerance and improve reliability into the integration process Using the feedback protocol applications may request to
43. e The second value message contains a short message describing the result of the error if the previous value is greater than 0 e The third value rule contains the content of the rule that was triggered Typical errors that can occur are files not delivered for any reason incoming files not accepted for being too big or for having an unauthorized extension URLE not found or empty generated Sightings Example In the example below the Hotspot was configured with a rule to deliver a file to all devices with their name matching the tag iwantfiles The Hotspot tries to deliver the file but the user leaves the space and the connection times out Then a feedback log is generated with the following content status 2 message connection timed out for device 00 a3 12 3a f4 rule deliverfile url http www bavaria com images boat jpg devname iwantfiles The status error numbers are not reported on this document because it is not relevant and because it depends on the implementation made Also messages generated are also not detailed These messages are merely informative 46 The feedback log indicates that the rule was performed with an error identified by the number 2 The error message describes that the connection timed out for the device with the address 00 a3 12 3a f4 4 3 Hotspot internal architecture In this section we describe the Hotspot internal architecture its main components and the i
44. e address starting with 00 17 E4 that have the tag iwantfiles on their name If the file could not be delivered the Hotspot will try again for more 2 times Then if the delivery to a device is succeeded the file will not be sent to that device again during the next hour deliverfile url http www bavaria com images boat jpg devaddress 00 17 E4 kx ok xx devname iwantfiles devclass CellPhone rememberfor 3600 retrytimes 3 4 4 4 Receiving files from Bluetooth devices This rule identified by acceptfile tells the Hotspot to accept files from user devices If one or more rules of this type are defined the service OBEX Object Push Bluetooth 61 service ID 0x1105 will be automatically advertised on the Hotspot and its visibility will turn on with the name Bluetooth Hotspot this name can be overridden with the argument advertisename From this moment on the Hotspot accepts all the files received and sends them over an HT TP POST request to the defined Device filtering for device address device name or device class is identical to the previous rule using the same three arguemnts This rule adds an extra filter for the file name of the received file Using a wildcard it becomes possible to filter files by extension e g filename jpg rejecting all the other possible extensions Thus the arguments accepted by the rule are e url the where to upload the file received
45. e is present the list of devices and the information collected by the Scanner the Sighting is sent on a HTTP POST request to an URL If a scan results on an empty list of devices the Sighting will not be sent to this unless the argument sendifempty is set to true Thus the rule accepts the following arguments e url defines the location where to upload the Sightings mandatory e sendifempty is a boolean value defining if the Sighting is to be posted even if empty Example With the rule of the following example the Scanner module will send all the Sighting files to the HTT P server located at http app1 com postsightings php even if the Sighting includes an empty list of devices postsightings url http app1 com postsightings php sendifempty true 4 4 3 Sending files to Bluetooth devices This rule identified by deliverfile tells the Hotspot to deliver a file to the present Bluetooth devices that have the service OBEX Object Push available Bluetooth service ID 0x1105 When this rule is present the Scanner will automatically inquiry the devices about their available services to understand if that service is available or not When the Scanner detects the presence of devices the file located at the URL provided is downloaded to the Hotspot and sent to all the devices seen by the Scanner Each device that accepts the file will not receive the file anymore until the next day except if the argument r
46. e list of addresses and names is delivered to the service that fills the screen with corresponding information In what concerns the Bluetooth related components the Instant Places architec ture represented in Figure is based on three main components 1 the public displays software which renders content to users 2 the Bluetooth scanners and 3 a central server that manages displays scanners and the context of the information that is displayed Despite these scanners currently being deployed as a piece of software running inside the same computer that controls the displays the system was designed to later support the Bluetooth scanner as an autonomous component running for ex ample on a small computer or a embedded device In this case the Bluetooth server component could be reused by different applications running on the same physical space All these components communicate over an network following a RESTful paradigm 17 1 scanners periodically send the result of each scan to the server and 2 displays periodically query the server for content to be displayed All this information Last fm Youtube Flickr http www flickr con 12 Third party services and applications flickr Y InstantPlaces lt gt woe applications In place Users devices mobile apps me 3 dicolays mobile LE Bay clients SMS amp laptop touch MMS clients surfaces Sensors Bluetoo
47. e to deliver one or more files to potentially interested users In this paper they propose a system based on multiple Bluetooth spots and a central server that manages the decisions of delivery and the state of the whole system The spots are constantly scanning for the present devices and sending this list to the central server For each scan the server checks if the file s was already sent to each device If it was not delivered yet the server contacts the Bluetooth spot again and gives order to deliver it However if it was already delivered the server will wait for a pre specified amount of time until trying to deliver the file again to that device This allows to deploy multiple spots without the problem of having a user roaming from a spot to another and receiving the same file multiple times roaming a devices a site 1 ON site store device list ice li j store device list for site 1 for site 2 backend information system Figure 2 7 Roaming devices switching between different Bluetooth sites Image adapted from 37 19 OpenProximity OpenProximity is an open source application oriented for Bluetooth content delivery identically to Bluemall and Omer Rashid s project However OpenProximity uses a single standalone computer to deliver files instead of dedicated Bluetooth APs The computer owns the Bluetooth interface but also acts as the state manager keeping in formation about which files were sent to
48. e to each of them With lFor these two Hotspots the configuration rules installed where exactly as the example shown in the example of the rule that enable device scans scan in Section 4 4 except the argument getnames which was set to false 14 around a thousand students visiting our department this became a good opportunity to validate almost all the designed components of the Hotspot We Installed two routers running this new version of the prototype one week for testing and one week for validation on the real scenario aiming at e to validate the management of multiple Bluetooth interfaces by the Interfaces manager e to compare the results of the Scanner in fast mode scan with the normal mode scan used on previous phases e to validate the OBEX file delivery e to validate the Configuration Rules structure with multiple types of rules defined and e to validate the patched PyBluez libraries and also the Light Blud libraries that ease the development of OBEX file transfers over Bluetooth Both the Hotspots were configured to 1 scan for the present devices and to 2 send the generated Sightings to the AnywherePlaces application in order to show the names of present Bluetooth devices in the public displays and to 3 send a welcome text file to each device this file was available at a on the AnyWherePlaces server The most important difference between these two Hotspots was the mode o
49. e use of two Bluetooth interfaces becomes mandatory if the performance of the Hotspot s interactions is crucial 5 3 3 Third phase At the moment of writing of this dissertation some key validation issues were still being evaluated This means that we could not acquire well grounded results yet but we still have chosen to describe the objectives of this phase even without results and even under development Thus with this validation phase we want e to get better results of comparison between using the Hotspot with the Scanner in fast mode scan and normal mode scan 16 e to evaluate how the Hotspot behaves when using OBEX file reception along with other Bluetooth tasks on real scenarios and e to deploy an extension in real scenarios installed on the Hotspot as a third party developed extension During this evaluation phase the Hotspot prototype includes a fully functional Receiver module and a Hotspot s extension developed with the objective of evaluating not only the extension mechanism but also the extension itself The exten sion that was developed intends to be adapted to Wiimote based interaction scenarios as surveyed in Section 2 5 It eases connections with Nintendo s Wii console remotes gt and its functionality is described in the next section 600 JPyMote Accelerometer data 7 x 129 Y 101 O Z 132 Infrared data X 368 Y 307 Size 4 6 Battery at 96 Connected to py
50. echanism already described in Section and 2 it obtains the name of each device exactly as described in the previous interaction refer to Section 2 2 Then 3 the user selects the device to which to send the file The phone queries the computer about the services 1t has available in order to know the availability of the file transfer service If the service is available 4 the phone tries to send the file to the computer using the channel associated to the service Some works in the area of Pervasive Computing are based on the idea of content delivery in other situations than the standard user to user one The delivery of files to user devices in the proximity can be used for delivering informations in public spaces like cities or museums for tourists or even for commercial purposing or advertisement 29 With a Bluetooth based infrastructure that is constantly aware of all the Blue tooth devices it becomes possible to deliver files to all of them or just to specific ones 377 88 2 3 1 Content delivery applications In this section we describe some works in the area of Pervasive Computing based on proximity sensing for content delivery that we consider relevant for this research 15 BlueMall BlueMall is a Bluetooth based advertisement system for marketing purposes on large commercial areas delivering information based on the clients current location 38 This paper describes a system architecture based on three softw
51. ed and deployed multiple instances of the Hotspot prototype Prototypes run on multiple Linux Ethernet routers and were used by two projects currently under development at our department This study mainly aimed at evaluating and validating three essential key issues of the system Integration model We want to evaluate the integration model between Bluetooth Hotspots and applications In particular we want to evaluate the Hotspot Con figuration Rules and the configuration process the device Sightings structures and the interaction model between the Hotspot and applications 3OpenWrt s table of hardware http wiki openwrt org toh start Python is an high level scripting programming language http www python org PyBlueZ is a wrapper that gives access to the BlueZ Bluetooth stack for Linux http code google com p pybluez 69 Figure 5 1 An Ethernet router equipped with an Bluetooth dongle running a prototype of the Bluetooth Hotspot software on OpenWrt Linux Stability and performance One of our goals is to design a system capable of run ning on an embedded device a Linux enabled Ethernet router The developed prototypes also have the objective of evaluating the viability of using OpenWrt Linux running Python and PyBlueZ libraries to support all the Bluetooth oper ations reported in Section 4 3 3 Viability of a reusable and shared component We want to understand which operations a
52. ed by an A cache of the downloaded files is maintained speeding up dependent processes avoiding unnecessary delays and excessive network usage This manager also holds an HT T P server This server is used by the Rules Manager to listen for the input of new rules Interfaces Manager This component manages the Bluetooth interfaces installed in the Hotspot usually USB dongles This implementation follows the requirements reported in the analysis of Section A Hotspot may have installed one or more Bluetooth interfaces This way a Hotspot may execute concurrent Blue tooth interactions Bluetooth Modules request a Bluetooth interface from the Interface Manager before executing the Bluetooth interaction At the moment of system startup the number of Bluetooth interfaces installed is obtained The bandwidth of each interface is abstractly assigned to 8 usage slots Each module or extension that wants to use an interface for a Bluetooth interaction will just have to request an interface also informing about how many slots it needs If there are enough free slots the module or extension is locked until the Interfaces Manager releases them After all the interactions performed the Bluetooth Module is responsible for freeing the slots If all the usage slots are in use the request will be added to a round robin queue until a sufficient number os slots are freed 4 3 3 Bluetooth Modules The Hotspot includes
53. ememberfor is defined with the number of seconds that should pass until the that device should be forgot However if the file could not be delivered for 60 any reason if a device does not accept the file or the connection fails the Hotspot will try again for 3 times or the number of times defined at the argument retrytimes The arguments accepted by the rule are e url the location of the file to be delivered mandatory e devaddress a string to filter the recipient devices by their device address e devname a string to filter the recipient devices by the human readable name e devclass a string or hexadecimal value to filter the recipient devices by their device class e g Computer or 0x100 e rememberfor the amount of time in second until next delivery after success default 86400 e retrytimes the number of retries until timeout for each device default 3 Device filtering If the file is not intended to be delivered to all the devices it is possible to define filters by device address by device name or by device class type of device These filters can include exact strings to match the devices or can be defined with a wildcard Thus the file will only be delivered if the expression s defined on the rule match the device s addresses names or services Example In the following example the file boat jpg will be delivered to all the Nokia cell phones devic
54. en inquiries each of them for its name A device name is considered old after 60 seconds and the available services after 3600 but this values can be override by the arguments namecache and servicescache Maximum time of a full scan Probably the most important argument for applications running on real time scenarios is scanmaxtime which specifies the maximum time between each scan including the time for getting the names and the available services of each device Note that this time will only affect the name and service getting phase and not the device scan phase itself Section explains why this argument is so important for the Hotspot performance Example In the following example assuming that two Bluetooth interfaces are in stalled on the Hotspot the Scanner will search for present devices exactly each 30 seconds on the first interface and get the names and services of each device on the second interface If a specific device is constantly seen it will be inquired for its name every two scans 30 30 seconds scan scaninterval 30 fastmode true getnames true getservices true namechache 60 servicescache 3600 59 scantimeout 8 nametimeout 8 servicetimeout 8 scanmaxtime 30 4 4 2 Sending Sightings to an application This rule identified by postsightings tells the Hotspot to send the results of each device scan to a remote HTTP server to be consumed by an application When a rule of this typ
55. en sent by the Hotspot A As depicted in Figure after the file being delivered by the Hotspot A the Main Controller is informed and configures the Hotspot B to ignore the device The next time any of the Hotspots detect the device it is ignored and the file is not delivered 3 2 3 Extensibility In connection oriented scenarios the context and information shared with users de pends on the application differing from application to application as analyzed in Section 3 1 4 This means that it is important to design a system capable of serving the most situations as possible Because it is not possible to foresee all the possible scenarios it makes sense to have an extensible architecture allowing further imple mentation of other application specific interactions With such mechanism it becomes possible to the application developers to implement extensions that achieve their tasks to be installed on the Bluetooth Hotspots One extension of this type will then respon sible for maintaining a connection with a device and another with the corresponding application turning the Hotspot in a bridge between both of them dO 3 es Eo Device X Hotspot A Hotspot B Controller deliver files to all dev deliver files to all dev l device X is seen 1 l get file adan device X is seen_ ieee Da DA oo es gt Figure 3 6 Sequence diagram i
56. ent client applications Performance data were collected to report the case studies 1 4 Structure of the dissertation This document is structured in five chapters Chapter 1 justifies this work resumes it and briefly explains how it is organized in different phases Chapter 2 includes a survey about related work on relevant studies applications and projects We intend to identify needs and requirements focusing in the context of Bluetooth interactions Chapter 3 presents a more detailed analysis of the patterns of interactions identified in the previous chapter and describes the architecture developed for the proposed system component The design of the system component we propose and how it can be implemented constitutes Chapter 4 The validation of this architecture is achieved with prototypes and their development This validation is described in Chapter Mobile and Ubiquitous Systems Group Universidade do Minho http ubicomp algoritmi Chapter 6 presents the most relevant conclusions and proposes future work derived from the work developed here Chapter 2 Related work In this chapter we survey relevant work in the area of Pervasive Computing that strongly builds on user interaction based on Bluetooth technologies The objective is to understand what kind of interactions with users are being used by Smart Spaces applications identifying patterns on those interactions This survey supports decisions about the
57. er the collection of nearby people hosts and accessible devices as well as to changes to such things over time 31 Smart Spaces as public spaces augmented with local computation 23 have been a test bed for experimenting smart meeting rooms 24 smart houses 22 smart classrooms 3 6 or smart museums applications Work on Reality Mining 16 Urban Computing or Mobile Social Software has broadly explored available sensors in the physical space and related sensing capabilities for applying and refining methods of observing recording modelling and analysing the city physically digitally and socially 83 In marketing mobile advertising has broadly explored pervasive computing environments for delivering permission based location aware mobile advertisements and other content to mobile users 38 Focus on the Bluetooth technology Bluetooth is a short range wireless technology which is presented in a wide number of handheld devices and requiring near zero configuration By this mean it became a powerful tool to be used for the interaction with physical environments and has conse quently been adopted for different applications and systems as a privileged technology of interaction 11 In fact many of the different cited works in the area of Pervasive Computing have broadly explored and evaluated the use of Bluetooth technology as a mean for implicit or explicit interaction with users Particularly Jos et al and Davies et a
58. er Bluetooth connections In this section we detail which is the role of each component Al Figure 4 1 An abstraction of the essential components of the system that evolve the Bluetooth Hotspots Applications Applications correspond to the services that can be offered to users when entering a physical space equipped with a Bluetooth Hotspot see Chapter 2 with multiple real scenarios These applications assume the presence of a Blue tooth interface able to interact with Bluetooth enabled devices In many cases this interface is attached to the server that supports the application s However in many scenarios as we have discussed in Chapter 2 it may be advantageous to have the Bluetooth interface physically detached from the application server Bluetooth devices Bluetooth devices are the mean for users to interact with avail able services in a space Those include cell phones PDAS laptops or any other kind of portable device The type of support for user interaction is dependent on the available services and on the type of interactions provided by the Hotspot In order to be detected by the system user devices should be set with the dis coverable mode on refer to Section 2 1 to understand what is this mode Bluetooth Hotspots Bluetooth Hotspots have the ability to establish multiple Blue tooth connections with multiple devices simultaneously They are designed to perform common Bluetooth in
59. ersions of the operating system and Python interpreter were due to stability issues During the development phase of the prototype recent versions of OpenWrt 10 03 and Python 2 6 were also tested but the system became really unstable with unwanted segmentation faults and spontaneous system reboots 5 3 1 First phase In the first validation phase only the Scanner Module was deployed This module was collecting device Sightings and sending them to the HTTP servers of InstantPlaces and AnyWherePlaces simultaneously The prototypes developed to evaluate the Hotspot on this phase are characterized for having 1 no support for multithreading 2 hard coded Hotspot Configuration Rules and 3 only one Bluetooth interface used for all the Bluetooth tasks to perform device scans to get the names and to get the services of the devices The objectives of this phase were e the validation of the proposed Sighting s structure e the evaluation of the scan duration times and e the evaluation of the robustness of OpenWrt running Python to perform the desired Bluetooth tasks Departamento de Sistemas de Informa o http www dsi uminho pt AnyWherePlaces A project in the scope of the a research program on Systems Software for Ambience Intelligence http ubicomp algoritmi uminho pt system software SASUS asus com 71 Despite the system had been designed to use YAML for data representation refer to Secti
60. et the available service of all devices If it takes more than 10 seconds to perform these steps the period of a scan will not be met Hypothetically if retrieving the name of each device takes 3 seconds as well as obtaining their available services when a scan is executed and 6 devices are present lFor full cycle scan we understand the full process of getting the list of discovered devices get the names of all devices 38 a Scan without maximum scan time time o 1 2 3 4 5 6 7 8 9 10 1 12 13 14 15 16 17 18 19 20 21 22 23 24 b Scan with maximum scan time defined to 10 time o 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 scan 3 Figure 3 7 Comparison between a scanner with a maximum time for scan defined b and a scanner without it defined a the whole process would take around 10 3x6 3x6 46 seconds which is greater than the expected 20 seconds To avoid this a maximum scan time should be defined to 20 seconds a new scan will be performed each 20 seconds in dependently of the number of devices detected and the success of name retrieval and services retrieval If there is remaining data to obtain from devices after the end of a scanning period that data will be retrieved in the following scan Conclusion There is not a perfect solution that fits all kinds of scenarios On the one hand the scan period can be hardly affected if a large number of de
61. etical device 33 33 33 33 33 33 were retrieved from a real device a Nokia E65 66 29 Headset Audio Gateway lastNameGet 2010 04 01 01 31 53 lastServicesGet 2010 04 01 01 18 34 67 Chapter 5 Evaluation In the previous chapter we have proposed an architecture for a Bluetooth Hotspot that supports Bluetooth based user centered interactions It is extremely important to evaluate how this architecture behaves on real scenarios during the design process because it allows to redesign some components based on the analysis of functional patterns The process of evaluation and validation is reported in this chapter organized in two sections first section enumerates the goals for evaluation second section describes how prototypes were deployed along with the results of each deployment 5 1 Evaluation environment To evaluate both the Hotspot s architecture and the integration model we have devel oped a few prototypes with the objective of being deployed in real scenarios T hese prototypes were designed to run on Linux enabled Ethernet routers like the one shown in Figurel5 1 In these routers we installed OpenWrt Linux operating system a Linux distribution optimized to run on embedded devices with low resources of memory and disk space This operating system allows to run all the essential features of our prototypes like e g running multiple multi threaded processes accessing a network and access the Bluetooth stack BlueZ
62. f rules containing the description of the station behaviour These rules allow to filter the list of seen devices by hardware address and to define time restrictions before delivering the files This makes possible to configure the stations to deliver different files to different devices in different moments Each Bluetooth station have at least two Bluetooth interfaces installed 1 one that is constantly scanning for the present devices and 2 the other s are reserved for sending files to user devices using the OBEX service 12OpenProximity 15Bluemarket 14BlueSender http www bluesender com ISFexmax http www fexmax com http www openproximity org http www bluemagnet com 20 This work also details many different tests done with the stations deployed in many different situations in the university bar in bus stations or shops Despite the focus of our work not being the acceptance of this interaction by different publics the work of Tiago Camacho becomes valuable as it determines the viability of content delivery using Bluetooth It also raises important issues for the design of our component which will be explained in Chapter 2 3 2 Both way file exchange Keith Cheverst et al propose a system that uses Bluetooth as a mean of interaction with a photo display Hermes Photo Display Users can 1 submit photos to the display using their handheld devices typically mobile phones or 2 download photos tha
63. f identifiers Each identifier can be followed by some parameters as shown in the following example scan scaninterval 30 getnames true getservices true postsighting url http app1 com postsightings php acceptfiles devclass CellPhone url http app2 com postfiles php deliverfile url http app2 com welcome txt devaddress 00 A5 BF In this example the list of rules tells the Bluetooth Hotspot to 1 scan for the presence of devices every 30 seconds retrieving their human readable names and the list of which services are available 2 for each scan send the information above to an application available at a specific Uniform Resource Locator URL 3 accept files from devices only cellphones and send them to a remote server available at the specified address and 4 also send a welcome file to all the devices detected which addresses start with 00 A4 BF 1 3 Methodology Along this document our research is reported in three main steps always aiming to achieve the stated objectives detailed in Section 1 1 Related work The first step of this work was a survey on relevant projects that use the Bluetooth technology as a mean of interaction with users Our objective The architecture of the Main Controller is not described on this dissertation as it is not the focus of our work Only the protocol of communication between it and the Hotspot is designed and detailed 3The example is presented in YAM
64. f scan while the first Hotspot had just one Bluetooth interface installed the second one had two With the Scanner module working in fast mode one interface was dedicated just for device scans leaving the second one for getting names getting services and sending files Results Only 10 of the attempts to deliver a file to the devices were successful All the other 90 fail due to rejection of the file by the user or due to time out This means that a problem of usability may exist which is not the focus of our work but may be an important result for the applications We aimed to analyze how much time a user had to wait for a file after entering on a space from the point of view of the Hotspot this corresponds to the amount of time between the first time a device is seen and the moment when a notice of a new file appears on the user s device screen 12LightBlue is a Python library that eases the access to Bluetooth operations of BlueZ Bluetooth stack in particular those related with OBEX file transfers and advertisement of Bluetooth services http lightblue sourceforge net 19 The average time of delivery was about 50 seconds even with some moments when 15 devices were present which is completely acceptable for all the studied scenarios of content delivery refer to Section 2 Also some users reported that their phones asked for a code to pair the phone After analyzing those devices we concluded that
65. from the user devices manda tory e advertisename the Bluetooth name of the Hotspot to be advertised to user e filename a string to filter the name of the file received from the device e devaddress a string to filter the recipient devices by their device address e devname a string to filter the recipient devices by the human readable name e devclass a string or hexadecimal value to filter the recipient devices by their device class e g Computer or 0x100 Filling the URL with relevant data When a file is received by the Hotspot and is sent to the defined URL the application that consumes the file will probably want to know 1 the name of the file and 2 whose device has sent it In order to pass this information to the application the tags filename and devaddress are available to be included in the appropriate place of the provided For example if the provided in the rule is http appi com post php addr devaddress amp file filename and a device with the address 00 11 22 33 44 55 sends the file star jpg to the Hotspot then the to where the file will be sent will be translated to http appi com post php addr 00 11 22 33 44 bb amp file star jpg Advertisement in multiple interfaces If multiple rules of this type are present a file received by the Hotspot will be sent to all the URLs defined in all those rules However if different rules define different advertise names two differen
66. guage to describe the Hotspot rules Compared with other mark up languages is very simple to be interpreted and manually written by humans Furthermore the performance is not affected when compared with and may even be substantially better for a small number of 43 elements This is particularly advantageous considering that the Hotspot software is intended to run on embedded devices with slow processors The YAML file describing the Hotspot rules is then submitted into the Hotspot This can be made directly by the application or by a configuration server considering that applications can access the Hotspot through the Internet protocols In this case the application uploads the file with the new rules over an POST In the case where the Hotspot does not have direct addressing the Hotspot can periodically download the Hotspot Configuration Rules from an URL on the network In both cases every time a new list of rules is submitted into the Hotspot it will assume the new behaviour 4 2 2 Hotspot sharing A Hotspot may serve multiple applications simultaneously We depict this situation in Figure In this situation we have defined a main point of control which will be responsible to maintain and submit the Configuration Rules to the Hotspot In this case the main point of control will be able to resolve any conflicts and provide the adequate degree of concurrency Figure 4 2 Representation of th
67. h device e g inform the application about a downloaded file a file successfully sent to a device or an error downloading or sending a file to a device 3 1 3 Receiving a file from a device Despite being a less usual scenarios some applications may also receive files from mobile devices In this scenario users send a document to applications which then En Device Hoispot Application process it same as showing an image on a public display 2 l behaviour l description advertise OBEX send file error ok send file Figure 3 3 Sequence diagram illustrating interactions for a Bluetooth Hotspot that receives a file from a device and uploads it to an application As illustrated in Figure 3 3 this type of interaction can be divided in the following 30 phases 1 Applications should configure the Hotspot with the list of devices allowed to send files white list and with URL where to store the received files 2 The Hotspot advertises the service and starts listening for new connections 3 Every time a user intends to send a document to an application the mobile device scans for the appropriate OBEX service previously advertised and initiates the documents OBEX transference 3 When the Hotspot receives a document and forwards it to a specific predefined Again the feedback about the success or failure of these tasks should be reported to the
68. how transfers works In the future with support from the extension mechanism many other scenarios and situations can also be evaluated It was possible to conclude that in most of the cases the utilization of more than one Bluetooth interface installed on the Hotspot is mandatory The performance of SU Bluetooth tasks becomes really affected while a device scan is performed which leads us to dedicate an interface just for this task leaving the other s performing other device s interactions Design and implementation obstacles Some implementation problems became an obstacle to the study and development of the Bluetooth Hotspot OpenWrt Linux distribution proved to be extremely stable but the implementation of the Bluetooth stack provided by BlueZ libraries did not Randomly but sporadically the Bluetooth stack loses the connection with the Blue tooth interfaces without any chance of recovery forcing the system to be rebooted in order to access the device again Despite the quickly reboot of OpenWrt on those kind of devices around 30 seconds this became a problem on real time scenarios where users could not wait so much time for an interaction Nevertheless these losses of con nection also happened when using just the BlueZ tools without our software On each evaluation phase tests were performed on a development environment before running the prototypes inside the deployed Ethernet Linux routers This allowed us t
69. hows an example where an extension extension 1 is started when a ot new scan occurs The extension is running until it decides to stop depending on its context In this example as it stops after the third scan when a fourth scan occurs the extension will be started again before receiving the Sighting resulted from the scan 4 4 Rules s structure The Hotspot Configuration Rules introduced in Section 4 2 1 describe how a Hotspot should behave The Hotspot s Rules List is a flat list which may contain any number of any type of rules In this section we explain with detail all types of rules along with an explanation about the arguments they support Each rule is followed by an example of configuration 4 4 1 Enabling device scans This rule identified by scan enables the device Scanner Module Almost all the other rules need the presence of this rule If defined without any argument only the hardware addresses of the present devices are periodically discovered This rule accepts the following arguments Time values are defined in seconds and boolean values are set to false by default For the numeric arguments the default values derive from the analysis of scenarios of the related work survey of Chapter e scaninterval defines the time to wait between each scan default 30 e fastmode is a boolean value that enables or disables the fast mode scan e getnames is a boolean value defining if the Scanner
70. it e Campus In 14 Nigel Davies et al have proposed Bluetooth based interaction communication with public displays hese displays present information from services search results from Googld videos from Youtube or photos from Flicki Using a technique similar to the one presented in 26 users submit commands to the display over their device names To interact with the display users define their device s name to tags with the search term they are interested like google lt search term gt or youtube lt search term gt or flickr lt search term gt and wait for the results to be shown on the public display Another application available on this system is an Audio Jukebox identical to the previous work Bluemusic users may suggest the music they want to be played on that place just by defining their device s name to juke lt song id gt This action adds the song associated with that id to the queue of musics that will be played Display machine Server application ere PH P process application control over f status lifecycle and viability received J Scheduler qieres Bluetooth Bluetooth received status scanner Sang queries aa a Figure 2 4 System architecture of e Campus Image adapted from 14 Many prototypes of these screens are deployed in the Lancaster University in the United Kingdom on a network of screens which they call the e Campus The architecture that supports this system represen
71. l BNEP extending a network With this protocol the accepts connections from a group of devices or establishes it when a specific device is seen near it Bluegiga s can be remotely configured over the network using a Secure Shell SSH console or using a Graphical User Interface GUI served over HTTP However it is designed to be configured interactively by the administrator via console or via GUI AJRESTful integration would be extremely important to improve its reusability OBEX sender application scans for nearby Bluetooth devices checks if found devices are in target group recognizes and tries to push selected content to target devices logs the served devices smart phone TCP IP Network Ethernet Wi Fi a GPRS or 3G ea IUC Ud 7 hianina solution Bluegiga me Manager Access oerver Figure 2 6 A network of devices connected to Bluegiga s Access Server by its built in Obexsender application Image adapted from Bluegiga s User Manual 18 Location based advertisement In the work proposed in 37 identical to Bluemall Omer Rashid et al propose a system for content distribution based on the location of users using Bluetooth Figure depicts an abstraction of this system With Bluetooth push servers Bluetooth spots capable of delivering files to users installed on a space and aware of the presence of devices it becomes possibl
72. l have explored an approach to support user interaction with public dis plays based on the Bluetooth Device Names A different kind of Bluetooth interaction based on OBject EXchange file exchanging is used 91 to disseminate contents to mobile users A mean for intuitive interaction using the Nintendo s Wii remote controller equipped with a Bluetooth interface is presented by various authors 40 41 Other types of interactions are oriented to a connection that is es tablished between the user device and some remote application or service using the Bluetooth infrastructure a Bluetooth interface or Access Point available on a space as an intermediary or broker between these two end points We argue that Bluetooth components may be managed as interaction resources in the physical space which can be shared and reused by different third party applica tions and systems This situation would set application developers free from Bluetooth management related issues and allow them to focus on application objectives Ad ditionally our approach may also contribute for the sustainability of the pervasive computing industry from an environmental perspective as it will enable sharing and reusing physical resources and potentially decreasing the number of local computing devices 1 1 Objectives The main scope of this dissertation is the proposal of a new system component centered on Bluetooth based user interactions to be used on systems and applica
73. lated work of Chapter 2 and in the analysis survey of Chapter 3 require a very fast scan for real time situations where a fast feedback is needed by the users The Scanner Module supports a mode of scan that speeds up the process by scanning with one Bluetooth interface and dO obtaining the Bluetooth device s names and services with another interface This mode is called the fast mode It monopolizes one of the interfaces just for scanning leaving the other s for all the other tasks This way the performance of the scan will never be affected Figure shows a comparison between these two modes where the Extra Device Information is requested after or during the scans respectively In the example of the figure the speed of this request is different for each device identified by numbers and one of the requests 6 marked as red times out Extensions module An extension is a software component that performs application specific Bluetooth interactions The Extensions Module integrates the available extensions with the remaining components of the system To integrate with the Hotspot extensions must be pre installed on the extensions directory of the Hotspot and implement three methods start newScan and stop The Extensions Module is responsible for maintaining the instance of each running extension All those three methods are called by the Extensions Module on the respective instance e The first method
74. led Logical Link Control and Adaptation Protocol which is the link layer protocol that supports RECOMM Many other protocols can be implemented for many application specific tasks depending on the context of the 21 application in question The most common scenario of a Bluetooth connection is a connection between devices of two different users Other typical scenario is a connection between two devices of the same user However some works are based on applications that use a connection between the user device and an infrastructure During the time that the user device is present in a place it becomes possible to communicate with the infrastructure until the user leaves the space We will now focus on two works that we consider to be relevant because they represent a set of identical applications oriented to this type of interaction LectComm LectComm is an open source software used to support lecturers during classes 6 Both the lecturer and students install the software on their devices Students run a client version of the software or access a web site with an on line version where they may answer questions and quizzes made by the lecturer who uses a server version of the software The communication between the client and the server is made over As most students do not have access to the Internet on the classroom LectComm provides a Bluetooth connection with an extended version of the client software applic
75. llustrating a situation where two Hotspots cover a space A file sent from a Hotspot to a user s device but is not sent again by any of the two Hotspots When to start an extension From the analysis of surveyed scenarios we identify that a Bluetooth interaction may be initiated in one of two situations a when a device is detected by the Hotspot or b when a user tries to establish a connection with the Hotspot The same pattern may be applied to the extension mechanism If the Hotspot is installed with an extension the extension may start in one of those two situations The Hotspot detects a device When a device is detected by the Hotspot s scan ner the extension starts if not yet started and is informed about the detected Bluetooth devices along with all the information collected about them hard ware address device name and available services With such information the extension becomes able to behave accordingly to the desired objectives e g to establish a connection with all the present devices A device establishes a connection with the Hotspot In order to accept incom ing connections from Bluetooth devices the Hotspot must be previously config ured to be listening to these connections So if these connections are handled by an extension the extension must be previously started in order to be listening Moreover the Bluetooth services must also be announced in order to allow the user s devices to
76. me of present Bluetooth devices in a public display installed near to each Hotspot Running this new version of the prototype all the Hotspots were installed with Internet connectivity to be able to reach the AnyWherePlaces applica tion The main objective of this deployment was the validation of e the performance of normal mode scanning where device scanning and name retrieval are performed consecutively refer to Section 4 3 3 e a mechanism to define a time out for device scans in situations for a large number of devices and 13 e system stability Each of the six deployed Hotspots was installed with just one Bluetooth interface running in normal mode scanning with scan periods of 30 seconds Two Hotspots were configured with the maximum time for each full cycle scan time which includes scan names of devices services available defined to 30 secondg and the three others were configured without this limit Results In the first phase of validation when the number of device was above 5 the time of a full cycle scan exceeded more than a minute in most of the cases This could be avoided with the definition of a maximum time for a full cycle scan However this could lead to a situation where some device names and services were not obtained For scenarios of silent scanning this problem is not so relevant if the time for keeping names and services in cache is high i e if a name or service could
77. not be retrieved in a scan it should be retrieved in next scans and then kept in cache However highly interactive scenarios where the devices names need to be constantly refreshed this cache time cannot be so high During all this deployment phase when we forced a value for a maximum scan time the mean number of scans needed to successfully get the name of a device was two 2 Without this maximum time defined the mean time was one 1 scan This situation turned mandatory the implementation of the fast mode scan described in Section and whose evaluation deployments are described in next section Some stability issues were detected on BlueZ libraries while running on OpenWrt which do not occur on the development environment when a large number of devices are present the BlueZ Bluetooth stack randomly lose connection with the Bluetooth interface forcing to perform a soft reset to the system We are expecting to use future validation phases to better study and to solve this issues as well as waiting for future updates to the implementation of these drivers and libraries for OpenWrt Content delivery During two weeks two Hotspots were deployed at our department in two different entrances For a week the AnywherePlaces project installed public displays for the School of Engineering s week from our university The objective was 1 to display the names of present Bluetooth devices and 2 to deliver a fil
78. ns are established the Hotspot acts as a bridge between the mobile device and the application The application should be informed about the success of fail of any task performed during the entire process Connection establishment from device side As depicted in Figure 3 5 a in some scenarios the connection establishment may be started from the device side instead from the Hotspot side In this case the device is not discovered by the Hotspot but the Hotspot should previously advertise the service and listen for incoming connections This scenarios follow the following steps 1 the Hotspot is configured to advertise a specific service and to accept connections from devices for that service 2 Every time a user intends to establish a connection with the Hotspot the mobile device scans for the appropriate service previously adver tised and initiates the connection 3 When a new connection arrives to the Hotspot on the service in question the Hotspot accepts it and also establishes a concurrent socket connection with the remote application that interprets the information 4 Af ter established the both connections the Hotspot redirects the data received from the Bluetooth connection to the application connection and vice versa Interaction s context independent of applications Some situations does not require the application to manage the context of the inter action In this kind of scenarios the connection is only establishe
79. nt on every event that occurs on the controller a variation on any accelerometer axis a variation on the sensor position or a button that is pressed is sent over this link to the console On the other hand the controller also accepts three kinds of input from the Wii console 41 1 enable disable each of four LED 2 enable disable the internal vibrator that is used to give feedback to the person who is holding the controller and 3 send a short sound to be played on a small speaker installed inside the controller As Wiimote communication is based on Bluetooth technology as opposition to the use of a proprietary protocol it can be used with any Blutooth enabled software component The work in introduces a new way of interaction in Smart Spaces using 24 Wiimote as a controller for public displays Holding a Wiimote users can navigate through pages of information shown on the screen using the arrow buttons The paper focus on the following scenario an interactive museum with multiple displays installed around showing useful information about the artworks and offering users the possibility to bring their Wiimotes from home and interact with those displays The prototype of the application that runs on the displays implemented in Java constantly scans for Wiimotes and establishes a connection with each device it dis covers This application only interprets inputs from the controller s buttons However gesture recognition accele
80. nteractions between each component a a MIUCLOUI MiQduics obex sender rules obex receiver logs scanner scheduler extensions y E Bj O Y AS O O D N 3 Ay O J O O W resources av ATA AYTANCINA CALCTISTUTIS Wiimote events channel PAN interfaces Figure 4 4 An abstraction of the internal components of a Bluetooth Hotpot The internal architecture of a Hotspot is organized in four groups of components illustrated in Figure 1 the Scheduler 2 the Hotspot Managers 3 the Bluetooth Modules and 4 the Hotspot Extensions We briefly describe each group below and detail its role in the following sections Scheduler The Scheduler is the component responsible for executing Hotspots tasks A task can be a Bluetooth interaction or a management task internal to the Hotspot typically an internal task is to enable disable a specific Bluetooth Module or to registry an entry in the log To achieve a correct execution of these tasks the Scheduler holds an event mechanism an events channel Both Bluetooth Modules and Bluetooth Managers can register events on this channel When an event is registered the Scheduler decides what to perform accordingly to the Configuration Rules that are currently loaded Then the task is executed AY Hotspot Managers These components perform specific internal tasks like 1 the management of the Hotspot Configuration Rules 2 the management
81. o identify that these unexplained issues came from the OpenWrt environment and not from our implementation We are currently in contact with the open source community of BlueZ and Python on OpenWrt trying to fix this problem and to obtain a stable solution Future work During this research some usability issues were detected that are out of the scope of our work but were predicted by other related works the increasing number of devices that are originally configurations as hidden devices or with short periods in the discovery state Another typical problem was the obligation of some devices to pair with a code before receiving or sending a file from to the Bluetooth Hotspot The duration of this work has not allowed to design and implement other important features related with scalability and security Our integration model does foresee any security issue but in a future phase we intend to design mechanisms of authentication authorization and accounting During our deployments we used PCP IP firewalls and Virtual Private Networks VPN to implement at least some of the security issue In what concerns the system scalability we foresee two design improvements 1 the Hotspot Configuration Rules should be installed directly from the applications and 2 the Hotspots should interconnect and synchronize the rules between them in multiple Hotspot scenarios This would free the utilization of the Main Controller simplifying 8
82. o systematize those user interactions This work is a basis for the design of a system component Bluetooth resource Proto types were developed and deployed in multiple real scenarios to validate not only the feasibility of using such a component on Smart Spaces but also the integration model with applications Such validation is presented on this document and works as a proof of concept for this component 111 Resumo Tanto na literatura cient fica como na ind stria especificamente na rea da Com putac o Disseminada e Espacos Inteligentes Pervasive Computing and Smart Spaces s o encontradas muitas aplica es e sistemas baseados em interac es impl citas e expl citas com recursos f sicos no ambiente tais como pontos Wi Fi receptores GPS componentes Bluetooth leitores RFID telefones m veis ou c maras Bluetooth uma tecnologia sem fios de curto alcance que n o requer configura es e que est pre sente num elevado n mero de dispositivos m veis Tornou se assim numa poderosa ferramenta para interac o com ambientes f sicos sendo consecutivamente adoptada por diferentes aplica es e sistemas como uma tecnologia priveligiada de intera o Actualmente estas aplica es e sistemas implementam os seus pr prios componentes Bluetooth capazes de executar tarefas especificamente relacionadas com as aplica es em causa tais como a obten o de informa o sobre os dispositivos dos utilizadores o
83. of the employees devices Experimental results show that this system provides a viable solution for permission based mobile advertising 38 Bluegiga access devices In the author refers the utilization of a commercial component the Bluegiga s APb as an alternative for the BlueMall A P Bluegiga Technologies Inc is an enterprise that develops Bluetooth based products The most relevant ones are the Bluetooth Access Point and the Bluetooth Access Server Both products are embedded devices that perform Bluetooth tasks oriented to the industry like eHealth Point of Sale POS proximity marketing and Internet sharing These are designed to be installed on public spaces and to act as an infrastructural anchors to be connected to devices like medical metering devices on a clinic or an hospital or to handheld devices on restaurants or cafes They can also be used for content delivery applications for marketing purposes delivering files to devices present near the APp The significant difference between the Bluegiga Access Point and the Bluegiga Access Server is the number of connections they can handle While the first one is equipped with just one Bluetooth interface it can keep 6 simultaneous connections with 6 different devices the second one is equipped with three interfaces allowing 18 simultaneous connections Both Bluegiga devices are equipped with an RJ 45 Ethernet port to connect to a network but
84. ogurl http app1 com postlogs php postsightings url http app2 com postsightings php logurl http app2 com postsightings php When one of these tasks is performed a feedback log is generated After the execu tion of the first rule their logs are sent to the address http app1 com postlogs php On the other hand the second rule sends the logs to a different address http app2 com postsightings php Independently of the rule that is performed all the referred feedback logs are also sent to the URL of the Main Controller located in http 192 168 1 50 logs create 4 5 Sighting s structure The result of each scan performed by the Scanner Module is a list of devices called a Sighting It is usually intended to be uploaded to a remote application refer to Section 4 2 Along with the list of devices a Sighting also contains the identification of the Hotspot and the date and time when the scan was performed e scannerName contains the name of the Hotspot that performed the scan e scanBeginTime defines the date and time the scan started at e scanEndTime defines the date and time the scan finished at e seqNumber defines the sequence number of the current sighting incremented on each scan e seenDevices contains the list of seen devices Each item of this list contains a device which must mandatorily include its 1 single hardware address Besides if it is known it also contains 2 the device s name
85. ompared to Simple Object Ac cess Protocol SOAP REST utilizes HTTP as an application protocol rather than as a transport protocol For this reason it introduces less overhead All the communica tions are realized by POST requests The messages formats are described in Sections and The procedure for integrating the system components is formed by 1 the mech anism by which applications define the Hotspots behaviour 2 the process for man agement the sharing of Hotspots between applications 3 the protocol for managing multiple Hotspots by the same application and 4 the logs report protocol The whole procedure is described in the following sections 4 2 1 The Hotspot behaviour The core process in the process of integrating applications with a Hotspot is the def inition of the Hotspot behaviour The Hotspot behaviour is defined by a set of rules known as the Hotspot Configuration Rules or simply the Rules List Each rule defines a task to be scheduled and executed by the Hotspot The type of rule is iden tified by a unique string e g deliverfile acceptfile or scan followed by a list of arguments that customize each task Typically these arguments specify character istics of Bluetooth interactions like the location of a file to be delivered or filters for the names of devices to interact In Section we detail the whole set of rules that can be installed on a Hotspot We rely on YAML Ain t Markup Lan
86. on 4 5 in this prototype we used a representation of Sightings with a structure suggested by the project InstantPlaces in order to ease the development and avoid the implementation of proxies to convert the data Silent scan and proximity sensing The InstantPlaces project has deployed two Hotspots at both entrances of our de partment and one at a high school Escola Secund ria das Taipas All of them were constantly and repeatedly collecting the addresses and names of Bluetooth devices During three months InstantPlaces applications were just silently collecting the Sightings from our Hotspots by silent we mean collecting data without being noticed by who is passing by and not showing any information to the users On a fourth month a public display was installed at the school displaying the name of Bluetooth devices linking this information with a Facebook application that shows the photo of device s users Additionally another Hotspot was deployed at Vila Verde s Library in Braga Portugal silently collecting device Sightings to InstantPlaces Results This phase allowed us to conclude that for silent scanning scenarios the Scanner period for each full cycle scad may be increased without too much impact if any device was not seen it would be like it was not present However if the user was expecting some feedback based on his presence the period of each scan could not be set in a magnitude of minutes but it
87. other devices in the prox imity usually to later establish some type of connection for data transfer This proce dure called the Inquiry Procedure 1 consists in broadcasting Inquiry Packets and then waiting for a response from the other devices in the neighbourhood All devices that are listening to those packets will reply with an Inquiry Reply packet that includes their own hardware address identical to an Ethernet Media Access Control address This allows the inquirer to uniquely identify the inquired device and later reach 1t to establish a connection In order to be able to receive Inquiry Packets devices should enable the Inquiry Scan State mode In this situation the device is in the discoverable state Failing to enable the Inquiry Scan State mode Bluetooth devices are hidden from other devices even if the Bluetooth radio is enabled Inquiry Scan State enabled device discoverable ing packet ing packet ing packet Sy E Inquiry Scan State disabled ing packet ing packet Inquiry Scan State enabled device discoverable O O Figure 2 1 Essential steps of an Inquiry Process where three devices are present two of them are discovered and one is hidden Figure illustrates a situation where a device A searches for the present de vices Despite existing three devices in the neighbourhood only two B and D will be discovered due to their responses with Reply Packets Cityware applications
88. performed too often in a short period of time the majority of those scans may not find a new device On the other hand if we decrease the scan frequency we may be creating an usability problem as it may lead the user to give up and probably to quit and probably leave the space Limit the duration of full scan Another situation that can produce unwanted behaviours is the presence of a large number of devices if the Hotspot detects a large number of devices and further executes the inquiry process for every device the total duration of the scan process may increase too much and fail to meet the performance requirements of the system This can lift the same usability problem referred above leading the user to quit This means that it is important to define a maximum time for each scan independently of 37 the number of devices At least the list of all devices should be created and submitted to the application even without some device names This will give the opportunity to the application to use at least the number of devices present and their hardware addresses Further information may be then submitted in subsequent scans The previous scenario is exemplified in Figure 3 7 with two hypothetical scanners e In the first situation a the scanner is not configured with any limit of time for scanning Thus the duration of a full cycle scan becomes unpredictable because it is not possible to know how much time it
89. plains how Hotspots integrate with other external system components Both the architecture and the integration model build on the analysis of Chapter The chapter is formed by five sections Section introduces the three main entities of the ecosystem that interact with a Bluetooth Hotspot explaining the role of each of them on the system Section describes the integration of the different components with the Hotspot and describes their main interactions Section 4 3 details the main aspects of the Hotspot internal architecture Section 4 4 describes the syntax and semantics of the Hotspot behaviour rules Finally section 4 5 details the structure of a Sighting a report generated by the Hotspot on each device scan 4 1 System components The Bluetooth Hotspot ecosystem is composed by three main type of entities 1 client Bluetooth devices 2 one or more Bluetooth Hotspot s and 3 a set of client applications systems Figure 4 1 depicts the essential components of a Bluetooth Hotspot ecosystem A Hotspot acts as a broker between Bluetooth devices and the remote applications sys tems The applications are willing to receive and provide data from to remote user devices through Bluetooth interactions e g to obtain Bluetooth device names through a Bluetooth scan or distributing a file through a Bluetooth Push interaction The integration with client applications is done over an IP network The interactions with Bluetooth devices are done ov
90. r i e if the Hotspot is configured with a rule for scanning it constantly scans for the present Bluetooth devices 59 OBEX Receiver Interfaces Module Manager l enable i PEER a E request O slots i reception cN new file received request 1 slot free 1 slot register event obexin Figure 4 6 Sequence diagram illustrating a OBEX Receiver Module that is enabled and a file that is received by the Module sent from a Bluetooth device as depicted in Figure Each iteration results on a list of devices hardware addresses his list associated to the date and time when the scan was performed is called a Sighting Sightings are useful for any action module or extension that want to deal with the list of present devices on a certain moment Sightings can also be passed to the external applications Every time a Sighting is generated this data structure is detailed in Section it can be locally stored on a file to be later retrieved It may also be uploaded to the of an application via HTTP if the Hotspot is configured with the rule with this objective refer to the rule postsightings in Section 4 4 Scanner Interfaces Module Manager I L__ lS l l request 8 slots scan loop register event newscan free 8 slots Figure 4 7 Sequence diagram illustrating a Scanner Module that is enabled and then perform multiple
91. reach the Hotspot 36 The extension behaviour As described above the behaviour of an extension will depend on the application that is using it To be able of serving multiple applications extensions have to be config ured by them in order to achieve the desired behaviour However the structure of such configuration completely depends on the extension and application Extension configuration should then be of responsibility of applications Applications are respon sible for managing and store a configuration file which is fetched by the Hotspot at the the moment the extension is initiated 3 3 Bluetooth related scalability issues During our review of existent systems we have identified a set of Bluetooth related technical issues which largely influence the technical behaviour of Bluetooth compo nents and thus also the technical behaviour of the Bluetooth Hotspot and Hotspot based prototypes In this section we enumerate those issues we understand to be more relevant All the items questioned here will later be taken into account when designing the architecture of the Bluetooth Hotspot reported in Chapter 3 3 1 Scanning frequency The three processes related with the scanning of Bluetooth devices scanning for devices retrieve their names retrieve their services may introduce unexpected performance issues if not performed with appropriate durations and times to timeout 20 On the one hand if scans are
92. reless and wired networks New York NY USA 2008 ACM pp 17 22 OO lt lt SATYANARAYANAN M Pervasive computing vision and challenges EEE Per sonal Communications 8 4 August 2001 10 17 40 LL SCHLOMER T POPPINGA B HENZE N AND BOLL S Gesture recognition with a wii controller In TEI 08 Proceedings of the 2nd international conference on Tangible and embedded interaction New York NY USA 2008 ACM pp 11 14 41 Li SEIXAS H SALGADO N AND Jos R Wiinteraction A study on smart spaces interaction using the wiimote In INFORUM 2009 pp 395 406 42 Lo SHERIDAN J G PRICE S AND PONTUAL FALCAO T Wii remotes as tangi ble exertion interfaces for exploring action representation relationships Workshop on Whole Body Interaction CHI April 2009 43 LO YOUNG S Bluetooth traffic monitoring technology Center for Advanced Trans portation Technology University of Maryland http www catt umd edu documents UMD BT Brochure_ REV3 pdf September 2008 S Acronyms list UML Unified Modeling Language HTTP Hypertext Transfer Protocol FTP File Transfer Protocol URL Uniform Resource Locator USB Universal Serial Bus XML Extensible Markup Language YAML YAML Ain t Markup Language REST Representational State Transfer SOAP Simple Object Access Protocol IR Infrared STL Standard Template Library CF Compact Flash WAP Wireless Application Protocol AP
93. rometer and motion tracking IR sensors can be added in the future using gesture recognition libraries like Wiiged 2 6 Discussion All the works covered by this survey use the Bluetooth technology as the main interac tion mean between users and applications available on a particular space To support this interaction system architectures are heavily based on a Bluetooth component that is installed at the same physical space as users This interface runs on a dedicated hard ware device usually called a Bluetooth node or Hotspot 9 for some systems and as a software that runs on the same machine that controls the place s applications for others 16 41 Generically we will call them just Bluetooth nodes Each system we have surveyed implements its own Bluetooth nodes just for their purposes and not designed for an optimized reusability environment Moreover these nodes either software based or hardware based become tightly coupled with the re maining infrastructure and can hardly be reused by other applications that share the same physical place Even wider featured solutions like the commercial Bluegiga see Section raise the problem of being hardware dependent based on proprietary hardware and software and not oriented for a coherent and autonomous integration as they need to be manually configured by the administrator via a console or a GUI There is no study of integration models between Bluetooth components and the
94. rs can interact with the environment using a Wiimote As explained in Section as an extension starts it receives an where to get the file with its configurations refer to Section for the rule that starts an extension For this prototype of the Wiimote Extension this file is an file with five elements e rumbleTime defines the amount of seconds to enable the vibrator of the Wiimote when a successful connection is established e sendTo defines the host name of the server application where to send the output from the Wiimotes e tcpPort defines the Transmission Control Protocol TCP port of the above server In order to clarify this issue please consider the following example lt xml version 1 0 encoding UTF 8 7 gt lt rules gt lt rumbletime gt 1 lt rumbletime gt lt sendTo gt 192 168 1 5 lt sendTo gt lt tcpPort gt 1234 lt port gt lt rules gt 18 This configuration file will make the Wiimote Extension to establish a TCP socket connection with a remote application that is running at the port 1234 of the server with the 192 168 1 5 When a connection between the Hotspot and a Wiimote is successfully established the Hotspot establishes the connection with the applica tion server and the Wiimote vibrates for 1 second Through this connection all the output from the Wiimote is redirected to the application for gesture interpretation 19 Chapter 6 Conclusions The main objective of this di
95. s all register event new scan newscan sight4 ega 7 request 8 slots E start hciO url Ro gt i newScan sight1 register event gt j o LB newScan sight2 newscan sight2 y sight sig gt register event i inanan sema PESA MeWScanisighis newscan sight3 sight3 Se i l stopped stop i free 8 slots free 8 slots hciO i i start hciO url i newScan sight4 lt Ie stopped sent Figure 4 9 Sequence diagram illustrating an extension that is triggered by Scanner Module s scans Instantiation of extensions When a new scan event is registered by the Scanner Module on the Scheduler the Extensions Manager will be always notified When this occurs the available extensions are also notified For each available extension if it is already running the extension is notified through the newScan method If is not running yet the extension will first be started with the method start receiving two arguments 1 the ID of the Bluetooth interface assigned to the extension and 2 an containing a file with eventual configurations of the extensions The Extensions Manager will download this file and provide it to the extension The semantic of this configurations will depend on the extension context so only the extension will be responsible for interpreting this file Figure 4 9 s
96. s not running yet the instance will be created Then when a Bluetooth interface is assigned the extension will start running as a thread The next time the rule is used triggered by a device that was seen the same instance will just be informed about the new device scan using an appropriate method refer to Section 4 3 3 If more than one application wants to use the same extension for different contexts multiple instances will need to be created one instance per application To achieve this each application specifies its own unique ID for their instance using the instanceid argument This ID can be a string or a number 63 Along with the name of the rule it is also required an where the configuration for the extension may be found This file contains all the configurations the application want to pass to the extension This way the arguments accepted by this rule are e extname the name of the extension to be run mandatory e configurl the where the configuration of the extension is located manda tory e startup is a boolean value defining if the extension will start when the Hotspot starts up or a new list of rules is loaded e instanceid the identification of the application that uses this extension e devaddress a string to filter the recipient devices by their device address e devname a string to filter the recipient devices by the human readable name e devclass a string or hexadecimal
97. s seen taking advantage of the scan mechanism that the Scanner Bluetooth Module offers The next five subsections describe with more detail all these components as well as the data structures that support them Sightings structure and Hotspot Configuration Rules structure The first subsection explains how the Scheduler manages the Hotspot tasks and the behaviour of the Hotspot The second subsection explains Managers functionality The third subsection describes the Bluetooth Modules focusing the most important issues of their design 4 3 1 Scheduler The Scheduler Module triggers the execution of Hotspot tasks typically Bluetooth interactions As it deals with asynchronous events the Scheduler holds an Events 48 Channel where Modules and Managers can register their events An event may have one or more associated actions to be triggered The decision of what actions to be performed will depend on the currently loaded Hotspot Configuration Rules Table 4 1 establishes the association that exists between registered Events and the corresponding actions to be executed In this table the wildcard matches with any event Table 4 1 The list of actions that may be triggered by each event Events Rules Triggered actions newscan deliverfile postsighting runextension obexin acceptfile newrules scan advertise ii postlogs Actions act as small pieces of software included on the Scheduler They use the a
98. scan devices in loop Optionally the Scanner Module can be configured by the Scheduler to retrieve more information about each device We identify this group of information as 54 the Extra Device Information and it includes at least the following data 1 the device class representing the type of device 2 the human readable name and 3 the Bluetooth services available in the device If configured to after each scan the Scanner will retrieve such information from each device storing it on a local cache The next time a new Sighting is generated this information about each device will be also attached to the Sighting The device scan process During a scan the Bluetooth interface that executes a scan is monopolized en tering on a state of high bandwidth consumption This means that during the scan no other Bluetooth tasks should be performed or its performance will be drastically affected For this reason before a scan the Scanner module requests 8 usage slots to the Interfaces Manager freeing them at the end of the scan Then an event newscan is registered on the Scheduler followed by an argument that contains the Sightings a Normal mode scan time hciO b Fast mode scan with two interfaces time Figure 4 8 An example that compares the performance of a scanner with the fast scan mode disabled and another with the fast mode enabled Normal vs fast mode scan Some scenarios detailed in the re
99. sent to the Bluetooth device If it is successfully sent an event obexout is registered on the Scheduler and the usage slot is freed by the OBEX Sender Module Resources OBEX Sender Interfaces Manager Module Manager get file gt send file i request 1 slot l i lt register event free 1 slot obexout Figure 4 5 Sequence diagram illustrating a OBEX Receiver Module that sends a file to a Bluetooth device OBEX Receiver Module This component receives files from Bluetooth devices The module has two states stopped and listening As depicted in Fig ure when the Module is in the listening mode because a rule caused the Scheduler to enabled it the OBEX Receiver module requests a Bluetooth inter face to the Interface Manager Then it advertises the OBEX Object Push service Bluetooth service ID 0x1105 on the assigned Bluetooth interface This enables the Hotspot to receive files from Bluetooth devices When a new file is received it is stored on a temporary directory and the event obexin is registered on the Scheduler along with an argument with the path where the received file was stored and another argument containing the sender s device address Thus any Scheduler s action will be able to access the received file to perform any task like for example sending it to an application Scanner Module When enabled by the Schedule
100. ssertation was the proposal of a new system component centered on Bluetooth based user interactions The work was essentially focused on these interactions We have surveyed related work with the objective of proposing an architecture of this system component the Bluetooth Hotspot We proposed and made its functionality available Such component may now be used in actual systems and applications as a Bluetooth interface that interacts with users mobile devices To evaluate the proposed architecture and integration model prototypes were developed and deployed in real scenarios gathering multiple and important results These results had extreme value during the design of our component but are also important as a case study for the involved projects Results The designed integration model that includes configuration rules configuration pro cesses feedback logs and file resources on a RESTful philosophy proved to work flawlessly with existing systems and applications During the evaluation phase these systems easily adapted to our Bluetooth Hotspot without any integration issue More over the objective of freeing the owner of the applications from Bluetooth related issues could also be fulfilled e g 1 application owners could retrieve the scan results in useful time just by defining a limit for a full cycle scan 2 the delivery or reception of a file to from users devices could be easily performed without understanding
101. t are being displayed submitted by other users touching them on the screen both using the Service The system is composed by four main components 1 a Linux server that imple ments the Bluetooth functionality of delivering files and receiving files to from devices 2 a shared file space for storing the photos to display 3 a presentation server that generates the form how pictures and which pictures will be displayed and 4 a presen tation client the photo display This display connects to the presentation server via a wireless network and presents the photos The screen of the photo display is touch sensitive to allow simple interactions with users 2 4 Connection based interaction The Bluetooth technology is used by many Human Interface Devices like mouses key boards or audio headsets to connect to user s computers or handheld devices Other devices like printers game console controllers or remote controllers also use Bluetooth to communicate This type of communication is usually performed over the RFCOMM Serial Cable Emulation Protocol protocol a transport layer protocol which emulates an RS 232 serial port Being a reliable protocol 1t easily supports the development of Bluetooth applications as 1t allows the creation of data sockets identical to sockets over this protocol However not all the applications want a reliable connection like audio or real time applications So may also connect over a lower layer protocol cal
102. t interfaces if available will be used to receive files advertising 62 the OBEX Object Push service on both interfaces Suppose the next Rules List as an example acceptfile url http app1 com files php advertisename BlueBox acceptfile url http app2 com postfiles asp advertisename BlueBox acceptfile url http app2 com postfiles asp advertisename GreenBox If the Hotspot is configured with the three rules of the above example it will ad vertise the OBEX Object Push service in two Bluetooth interfaces with different names 1 the name BlueBox is used in one Bluetooth interface and 2 the name Green Box on the second interface Thus all the files sent from devices to the Hotspot using the first interface will be sent to both the http app1 com files php and http app2 com postfiles asp The files sent to the Hotspot using the second interface will only be sent to the second 4 4 5 Starting an extension This rule identified by runextension tells the Hotspot to start an extension iden tified by a string with its name If the argument startup is defined to true the extension will start when the Hotspot starts up or anytime a new list of rules is in stalled Otherwise if this argument is not defined the extension will only start when at least one device matches at least one of the filters device address device name or device class When the extension is requested to start if i
103. ted concurrently in different contexts Event s arguments An event may be defined by a set of arguments which retain the data that is generated by the occurrence of the event for example the event newscan registered by the Scanner Module appends the Sighting generated con taining the list of seen devices These arguments are passed to the corresponding action to be executed Rules s arguments A rule may be constrained by a set of arguments refer to Section 4 4 for the list of arguments accepted by each rule Every time an action is executed along with the occurrence of an event the rule s arguments are also passed to the action For example the deliverfile rule has two arguments which correspond to the name of the file to be delivered and the list of devices which are passed to the corresponding action The action execution context is expressed with the following expression event a rule b action a b If a certain event is instantiated as X a rule as Y and an action as Z where Y and Z have the same name this expression can be interpreted as when event X with arguments A occurs if the rule Y with arguments B is contained in the list of loaded rules the action Z is executed receiving the arguments A and B 4 3 2 Hotspot Managers The Hotspot Managers or just Managers are responsible for the basic functional tasks of the Hotspot This includes managing the Rules List obtaining and c
104. ted in Figure 2 4 is identical to Instant Places with a central server that manages multiple screens and each screen is equipped http www google com http www youtube com http Google search engine YouTube video service Flickr photo stream WT ancaster University www lancs ac uk 14 with a Bluetooth scanner For each display the scanner a piece of software running on the same machine of the display constantly searches for the present Bluetooth devices and collects its current name his information is sent to the central server using a low level Application Programming Interface API The server decides what information is to be shown based on the data collected by the scanner and creates a playlist of data to be shown on that screen Following a publish subscriber messaging pattern the screen periodically consults this queue and shows the available information to users This way scanners act as input devices for users and screens as output devices for the system 2 3 File exchange based interaction Bluetooth is often used to exchange files between devices like computers PDAP cell phones and smartphones T hese transferences are usually performed over the Bluetooth OBject EXchange protocol OBEX When a user wants to send a file to another device for example from a phone to a computer 1 the phone scans for other Bluetooth devices using the inquiry mechanism m
105. tely available over the network This means that a file can be identified by an 34 URL both if it is locally or remotely stored In this case before being sent to a user s device it will be downloaded over the network and temporarily stored on the Hotspot to be sent Also the reverse happens when the Hotspot receives a file from a user s device the Hotspot receives the file and stores it If the URL is a remote location the file is sent over the network to the appropriate application and then it is removed from the Hotspot 3 2 2 State management In most of situations a Hotspot is enough to cover a space of interaction However to cover larger physical spaces multiple Hotspots may be deployed In this scenarios it may be required the Main Controller to manage the context between all the Hotspots A task executed by a Hotspot may require any type of synchronization actions with other Hotspot in the same space Typically this situation is observed in scenarios where a Hotspot delivers a file to a device and all the others must assume that the file should not be delivered again to the same device For example when a user enters a museum equipped with two Bluetooth Hotspots and an informative file is delivered the Hotspot A detects the device and successfully sends it a file Then the user moves across the museum and a Hotspot B also detects his presence but the file is not delivered because it already has be
106. teraction tasks as efficiently as possible Using a Bluetooth Hotspot applications become free from understanding how to establish Bluetooth connections with Bluetooth devices Applications are responsible for configuring the Hotspot behaviour using rules defined by the Hotspot Behaviour Rules set in Section we detail this mechanism After having configured a Hotspot applications will wait for or initiate the interactions correspondent to the defined behaviour e g sending a file to a device or receiving a periodic list containing the Bluetooth device names from devices in the Hotspot s range 42 4 2 Components integration Bluetooth Hotspots are autonomous components in the way that they can indefinitely perform most of the interactions with users devices without depending on other ex ternal components These interactions with devices are however defined in the context of an application So interaction data is transmitted from the Bluetooth Hotspot to applications and from applications to the Bluetooth Hotspot for every defined inter action When receiving the interaction data applications will process that data in the context of the application logic Application logic is also responsible for generating data that is communicated to the Hotspot in order to be delivered to users devices We rely on the Representational State Transfer REST paradigm to achieve communication between Hotspots and applications C
107. th scanner desktop amp mobile browser YW ve E eas E ET Q 5 280 D le EE Hop Bluetooth OBEX Figure 2 3 An abstraction of InstantPlaces architecture Image adapted from technical documentation of Instant Places is exchanged on Extensible Markup Language XML and sent to the server over an Hypertext Transfer Protocol HTTP POST packet Bluemusic In the Bluemusic system the Bluetooth device name is used to personalize a public environment where users may suggest artists or musics to be played just by changing the Bluetooth name of their devices to specific tags If there are more than one user in the Bluetooth proximity area the system identifies the preferences shared by most of the users This paper briefly introduces other possible scenarios that can be based on the same kind of interaction like adjusting the temperature of the office by user suggestion or by suggestion of a group of users or suggesting news for a public screen In all the above scenarios users are able to interact with system without the need to install an application on their devices The Bluemusic software runs on a computer equipped with a Bluetooth interface an internal interface or a Universal Serial Bus dongle and running the pro totype software Bluemusic periodically scans and retrieves the name of Bluetooth devices in the proximity parses them for the name Bm followed by the name of the 13 chosen music and considers to play
108. the moment a device enters in the range of a Hotspot and the moment a Sighting containing all the information collected from a full cycle scan is generated to be send to remote applications was between 30 and 90 seconds with most of the cases taking less than 60 seconds 5 3 2 Second phase The second phase of validation was essentially intended to validate all the system components multithreaded and coordinated between them As PyBlueZ libraries does not support multiple Bluetooth interfaces we have developed a patched version of this library to support this feature in order to use the Interfaces Module as it was designed refer to Section 4 3 2 Many Hotspot s prototypes were deployed in different contexts to evaluate its performance and integration in scenarios of 1 proximity sensing and 2 content delivery as detailed below Device Name interaction for proximity sensing This stage of evaluation was an extension of the first one to systematize its results We installed the same two Hotspots at 1 our department entrance and another four in four different high schools 2 Escola Secund ria de Camilo Castelo Branco Vila Real 3 Escola Secund ria de Mirandela 4 Escola Secund ria de Valpacos and 5 Escola Profissional de Felgueiras During three weeks each of these Hotspots was collecting device Sightings to the AnyWherePlaces application running at our department With this data the applica tion was presenting the na
109. the second one is also equipped a Wi Fi card and an port allowing it to be equipped with a General Packet Radio Service GPRS or a 3G USB card Bluegiga s software is implemented with the Linux operating system and of fers its own Software Development Kit SDK This gives the possibility for developing specific applications for specific scenarios However basic commons applications are natively supported like sender With this application the can deliver files to groups of devices Constantly scanning for the present devices the will deliver a file locally or remotely stored somewhere on the network to all devices that match with the groups filter depicted in Figure 2 6 These groups are defined with filters for device class name hardware address and even the distance from the AP to the device All events are logged for further analysis 11 Bluegiga Technologies Inc http www bluegiga com 17 OBEXI receiver The may also receive files over Bluetooth locally storing them or uploading them to a remote server SPP over IP Connections for specific tasks may be performed over this protocol It allows to establish an end to end connection between the user s devices and a remote server accessed over With this protocol the acts like a bridge between these two ends PAN The can be configured to share an Internet connection to Bluetooth de vices over the Bluetooth Network Encapsulation Protoco
110. this process of pre pairing is manda tory for some models meaning that automated file delivery as desired was not possible for those kind of devices This lifted another usability problem which may be studied in a future phase There was a big difference of performance between a Hotspot installed with one or two Bluetooth interfaces Single Bluetooth interface Even defined with a period of 30 seconds between each scan the router with only one interface installed and thus using normal mode scans performed many full cycle scans scan get names get services that took more than 60 seconds Furthermore when a max full cycle scan time of 30 seconds was forced half of the names could not be retrieved which was unac ceptable for the current scenarios Multiple Bluetooth interfaces The other router with two Bluetooth interfaces installed configured with the fast mode scan enabled which means that one of the interfaces becomes dedicated to devices scans could obtain the names and services of almost every device even when delivering files in parallel Moreover also the scan duration time was respected most of the times with an effective scan mean duration of 15 seconds when a small number of devices is present and a mean duration of 30 seconds when a large number of devices is present This means that scenarios where a large number of devices are present both content delivery and scan scenarios th
111. ting interactions of a Bluetooth Hotspot that searches for the present devices gets its names and send this information to a remote application 3 1 2 Sending a file to a device In content delivery scenarios files are sent to user devices as soon as they are detected BlueMall or OpenProximity are examples of applications that fit in this type of scenarios For these scenarios we envisioned the following interactions as illustrated in Fig ure 1 Applications should configure the Bluetooth Hotspot with the location where to get the files an or File Transfer Protocol location and the list of devices to which send the files commonly called a white list 2 Every time a device from this list is present 3 the file must be downloaded from its Simulta neously the device is inquired about the availability of the OBEX service If available 4 the file is sent to the device using the OBEX protocol To be able to keep track of the Hotspot behaviour the application requires feedback about success or failure of these tasks So logs should be reported to the application 29 8500 20598 sE RS Device Hotspot Application behaviour description device is seen gt l i get file l l A get services DE send file i report error ok l Figure 3 2 Sequence diagram illustrating interactions for a Bluetooth Hotspot that sends a file from an application to a Bluetoot
112. tional work has to be done to improve the integration process such as the study of Hotspot registration and discovery process but in our opinion this is a preliminary result and contribution for the sustainability of Pervasive Computing industry OpenWrt s software repository http wiki openwrt org doc packages 32 Bibliography 1 Bluetooth core specification v2 0 technical report Tech rep Bluetooth Special Interest Group November 2004 2 AALTO L GOTHLIN N KORHONEN J AND OJALA T Bluetooth and WAP push based location aware mobile advertising system In Proceedings of the 2nd international conference on Mobile systems applications and services New York NY USA 2004 MobiSys 04 ACM pp 49 58 3 ABOWD G D Classroom 2000 An experiment with the instrumentation of a living educational environment IBM Systems Journal 88 4 2000 508 530 4 ABOWD G D EBLING M GELLERSEN H W HUNT G AND LEI H Guest editors introduction Context aware computing EEE Pervasive Comput ing 1 3 2002 22 23 5 AHMED H EL DARIEBY M ABDULHAI B AND MORGAN Y Bluetooth and wi fi based mesh network platform for traffic monitoring In Transportation Research Board 87th Annual Meeting 2008 6 BAR H HAUSSGE G AND ROSSLING G An integrated system for interaction support in lectures SIGCSE Bull 39 June 2007 281 285 7 BARDRAM J E HANSEN T R AND SOEGAARD M Awaremedi
113. tions original Bluetooth components are now replaced by the Bluetooth Hotspot This chapter is organized in four sub sections that correspond to four groups of Bluetooth interactions that share identical characteristics We will focus not only on interactions with users but also on interactions with applications that will be using this new system component Secondly in section 3 2 we identify relevant key design issues for the architecture of the Bluetooth Hotspot gathered from the analysis of Section 3 I and from the survey presented in Chapter 2 T hirdly in section we report the most relevant Bluetooth related issues col lected from the survey in what concerns the system scalability contributing for a more sustained implementation 3 1 User interaction patterns With this analysis our objective is to identify types of Bluetooth interactions between users and the system components In short the common components widely present in all systems or projects we have studied are 21 e User s devices that are able to or waiting to interact with an application or with a system near them in the same physical space e A Bluetooth interface one or more that is able to perform Bluetooth tasks acting as a bridge between users and applications e Applications willing to interact with users over Bluetooth Usually those Bluetooth interfaces appear integrated with the applications in cause anchored to specific tasks
114. tions centered on situated applications The focus of the work is on these interactions Our goal is to design more than just an interface with the user we want this component to be self contained and able to be easily installed configured and used the concept of a small box that after being installed becomes a resource available for different applications With this component it should be easy to create diverse interactive spaces which uses Bluetooth as a mean of interaction For instance as a support for visits to museums thematic parks or entertainment in urban computing In the area of Pervasive Computing many works are being developed using this mean of interaction which has lead us to establish three main objectives for our work To study the user interactions of relevant Bluetooth based systems This study aims to analyze patterns in user interactions Deeply understanding how related works are implementing their own Bluetooth interfaces is crucial to sys tematize our work This is the first step towards the implementation of the next two objectives Furthermore this study is relevant by itself as it offers a state of the art survey for works centered on user interaction over Bluetooth To design the architecture of a Bluetooth Hotspot We aim to specify an architecture for a new system component that works as a bridge between Smart Spaces applications and user s Bluetooth devices Our intention is to gather on
115. u trocas de ficheiros com estes Nesta disserta o argumenta se que os componentes Bluetooth podem ser tratados como recursos de intera o do espa o f sico com a possibilidade de serem partilhados e reutilizados por diferentes aplica es e sistemas Desta forma liberta se os seus progra madores de quest es relacionados com a implementa o e gest o espec ficas da tecnolo gia Bluetooth incentivando os a focarem se nos objectivos da aplica o Al m disso a nossa abordagem poder tamb m contribuir para a sustenta o da ind stria da Com puta o Disseminada sob uma perspectiva ambiental dado que ir permitir a partilha e reutiliza o de recursos f sicos reduzindo o n mero de dispositivos computacionais Neste trabalho estudam se projectos e aplica es relevantes para a ind stria da Computa o Disseminada e Espa os Inteligentes que recorrem tecnologia Bluetooth como uma forma de interac o com os seus utilizadores S o identificadas as carac ter sticas comuns destes projectos tratando se de um passo importante para a siste matiza o destas interac es Este trabalho constitui a base do desenho de um novo recurso Bluetooth Foram desenvolvidos e instalados prot tipos em v rios cen rios reais a fim de se validar n o apenas a viabilidade de tal componente em Espa os In teligentes mas tamb m o modelo de integra o com as aplica es Tal valida o apresentada neste documento
116. vailable Bluetooth Module to perform Bluetooth interactions and Hotspot Manager to perform internal management Using Rules as filters for Actions execution Rules act as filters for the execution of actions When an event is registered in the Events Channel the Scheduler consults the Rules Manager for the list of currently loaded rules If the list is empty nothing is done If there are loaded rules the Scheduler checks the Table 4 1 for actions associated with the event Each action is executed the same number as the number of times a rule with the same name appears on the loaded Rules List This means that if a rule X appears three times on the list and an event triggers an action X the same name as the rule the action X is executed three times in parallel For example when the newscan event is registered in the channel the possible actions to be executed are deliverfile postsighting and runextension accord ing to the table Assuming that the Hotspot is configured with two deliverfile rules with different arguments for different applications or contexts then the action deliverfile will be performed two times in parallel The event newscan is registered by the Scanner Module after performing a new device scan 49 Action execution context The actions execution contexts are defined by 1 the trigger event data arguments and 2 the associated rule data arguments Consequently correspondent tasks may be execu
117. value to filter the recipient devices by their device class e g Computer or 0x100 Example With the rule of the example below the Hotspot will start the extension wiimote when at least one device with the name starting with Nintendo is found runextension extname wiimote configurl http app1 com wiimoteconfigs txt devname Nintendo 4 4 6 Feedback logs The Hotspot holds a mechanism of feedback to the applications As described in Section feedback logs can 1 be delivered in a specific location for each defined rule or 2 be delivered in a unique location for the entire Hotspot The first method is performed passing an extra argument logurl to the rule in question All the rules accept this argument It includes the where to deliver the feedback logs of that specific rule The second method delivers all the feedback logs of the Hotspot in a unique without the need to specify it on every single rule With this objective the Hotspot accepts a rule identified by postlogs that receives one argument e url contains the location where to send the feedback logs mandatory 64 Example In the example below the Hotspot is configured with two rules hese rules tell the Hotspot to perform two types of tasks to accept files from devices and to send the generated Sightings to an application postlogs url http 192 168 1 50 logs create acceptfile url http app1 com files php l
118. verage speed of a car on that road section if the car is observed by two scanners The Center for Advanced Transportation Technology of University of Maryland has developed a box which can be deployed on the street which periodically searches for devices around it and stores the collected data internally for posterior download and analysis The work presented in describes an identical system that uses a Wi Fi network to access the Bluetooth nodes device scanners and remotely retrieve the Bluetooth collected data 2 2 Device name based interaction Each Bluetooth device can handle a short human readable name for easier identifica tion Bluetooth Human Interface Devices HIDE like audio headsets Bluetooth GPS receivers mouses or keyboards are generally assembled with a static name However computers and handheld devices like PDAS cellphones and smartphones allow the user to configure its Bluetooth name A typical situation where this name is useful is when a user wants to transfer a file to another device or connect to an audio headset 1 first the user device scans for the presence of other devices situation identical to the interaction of the previous section 2 1 2 then for each device found the name is The Bluetooth device class is a number that corresponds to the type of device e g a cellphone a laptop a desktop computer Center for Advanced Transportation Technology of University of Maryland http www c
119. vices is present but their names and services can be retrieved on time On the other hand to ensure that the scan period is respected configuring a maximum time for scan the performance of retrieving the devices names and devices services will be hardly affected The decision of choosing one situation or the other will depend on the scenario However if multiple Bluetooth interfaces are installed on the same Hotspot these tasks can be performed in parallel if two interfaces are available one can be used for scanning while the other can be used for retrieving device names speeding up the entire process This situation is analyzed below 99 3 3 2 Multiple Bluetooth interfaces Some real scenarios may involve a large number of simultaneous tasks on the same Hotspot However there are some technical limitations that can deteriorate the opera tion of the Hotspot The performance of a Bluetooth connection will depend on issues like wireless interference available bandwidth or limitations of the protocol While implementing the Bluetooth Hotspot we do not have any control on the first one as it depends on many factors like the distance between the Hotspot and user s devices or the presence of other radio devices interfering with the Bluetooth communication Also the second one that evolves management of bandwidth is not a concern because the Linux Bluetooth stack manages the available bandwidth between all the
120. which devices It can be configured graphically via an HTTP interface or configured via Remote Procedure Call RPC requests OpenProximity works with at least two Bluetooth interfaces one interface is used to constantly scan for Bluetooth devices and the other s interface s are responsible for delivering files The software supports up to 15 Bluetooth interfaces simultaneously installed sending 7 files at the same time with each interface This means that the oretically it can handle up to 105 connections with 105 different devices at the same time With multiple configurations multiple files can be delivered by OpenProximity for different contexts The configuration of a file to be delivered is called a campaign If a campaign is created without any filter the file is delivered to all present devices through the available OBEX service However filters can be defined to create time restrictions when to start and when to end the campaign or filters for devices Devices can be filtered by name class type of device or hardware address There are identical commercial products on the market like BlueMarket Blue Sendell and Fexmax Bluestation In his master thesis Tiago Camacho proposes a system with Bluetooth stations capable of scanning for the presence of devices and delivering files to them 9 A Bluetooth station is a computer running the Bluestation software pre configured with a list o
121. will get the name of each device after each scan e getservices is boolean value defining if the Scanner will get the available services of each device on each scan e namechache defines the amount of time that a name is kept in cache when obtained in a scan default 60 e servicescache defines the amount of time in seconds that the list of services is kept in cache when obtained in a scan default 3600 e scantimeout defines the duration in seconds of each scan until it times out default 8 The scan time can vary depending on the number of present devices specially if the fast mode isn t enabled and the names and services inquiries are enabled IS e nametimeout defines the duration in seconds of the process of retrieving the name of a device until the process times out default 8 e servicetimeout defines the duration in seconds of the processing of retrieving the available services of a device until the process times out default 8 e scanmaxtime is the maximum time in seconds of each scan get names get services This value forces the Scanner to stop after this time even if one of the tasks is not completed default 30 Fast mode device scans The argument fastmode assigns the Scanner to one Bluetooth interface leaving the inquiries of names and services to a second interface if available Unless the argument fastmode is set to true the Scanner searches for the present devices th
122. with this Hotspots is to provide more reliability to the system and to allow the implementation of situated applications There are no details about how this Hotspot is implemented but for our research we just need to focus on the idea that a Bluetooth connection is established between the Hotspot and every user device that runs the BluetunA software Internet connection sharing Being a short range protocol Bluetooth is widely used with personal devices like mouses keyboards audio headsets PDAB cellphones and computers It is possible to interconnect most of these devices on an Ethernet like network with IP addressing This is possible due to a protocol that allows the creation of Personal Area Network between Bluetooth devices 25 It also becomes possible to establish a network not only between user devices but also between user devices and an infras tructure of Bluetooth Hotspots This protocol is useful to share an Internet connection to Bluetooth enabled handheld devices that are not equipped with Wi Fi The Bluegiga s Access Points and Access Servers already described in Section also offer this service to the nearby devices 2 5 Wiimote based interaction In 2006 Nintendo Co Ltd released the Wii a new home video game console differen tiated from similar consoles by its innovative wireless remote controller the Wiimote Beyond the classic game controller s arrow and auxiliary buttons this controller is equippe
123. x that Bluetooth Extended Naming http ubicomp algoritmi uminho pt ben 11 allows users to describe user related information using a low number of characters For example to share their interests on specific news topics e g tag radiohead to vote on polls e g vote braga or to share their ID of services like Last fm Youtube or Flick e g id flk mary InstantPlaces In a public space like a bar a school or a hotel hall public displays can be installed containing news weather advertising quizzes polls photos or other kind of useful information for that places Instant Places is a project that explores how Bluetooth can be used for interaction with public situated displays 27 Users can suggest what kind of information they are interested to see on the screen vote on a poll or provide personal information to show on the screen like their own name This is done by setting the human readable name of their Bluetooth enabled devices using the abbreviation syntax of the technique Each display is installed with a Bluetooth scanner which is constantly getting information about the present user devices This cyclic procedure consists of two phases 1 a phase of scanning using the Bluetooth Inquiry Procedure already described in Section which results on a list of hardware addresses and 2 a phase of name discovery for each seen device on the first phase resulting on a list of strings After each cycle of scanning th

Bluetooth Hotspots for Smart Spaces Interaction

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