Delta User Guide - Université de technologie de Troyes
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1. occurrence gt lt time gt lt targets select topology gt lt action mode all gt lt method name gt getMeasurement lt method name gt lt method params gt lt param gt lt param type gt java lang String lt param type gt lt param name gt metricName lt param name gt lt param value gt DISTANCE lt param value gt lt param gt lt param gt lt param type gt java lang String lt param type gt lt param name gt measurementId lt param name gt lt param value gt 0x0001 lt param value gt lt param gt lt param gt lt param type gt java lang String lt param type gt lt param name gt component lt param name gt lt param value gt null lt param value gt lt param gt lt param gt lt param type gt java lang String lt param type gt lt param name gt correlator lt param name gt lt param value gt null lt param value gt lt param gt lt method params gt 17 12 17 13 18 23 28 lt action gt lt task gt 2 8 3 Gathering results of measurements The results of measurements are written in the output file as specified in the configuration file In this file each measurement is written on a single line that contains the following fields e Expected measurement time in milliseconds e Time of actual measurement start in milliseconds e Time of actual measurement end in milliseconds e Metric identifier e Occurrence number of the measuremen2. 215 220 230 235 240 250 3 3 OpenChord In this section we show how we plugged DELTA with OpenChord 7 Java based implementation of the Chord DHT 2 As for the Pastry use case we designed a class called ChordServer which implements the P2PRemote Instance interface One can note that since OpenChord does not support any life cycle control 1 the state of all nodes is always set to alive and 2 methods related to life cycle changes are not implemented The full code of the ChordServer class is given in listing 18 and again the implementation of this class should be considered as an example but not as a reference since althrough it enables us to perform our tests appropriatly it may have to be reconsidered in order to be used in another context Listing 18 The ChordServer class package fr utt era deltaappls chord import java net import java rmi RemoteException import java util import java util regex import de uniba wiai lspi chord data URL import de uniba wiai lspi chord service import de uniba wiai lspi chord service impl ChordImp1l import fr utt era delta DeltaMeasurement import fr utt era delta p2p P2PRemoteInstance public class ChordServer implements P2PRemoteInstance private String bootstrapAddress private int bootstrapPort private final int FIRST_NODE_PORT 20000 private int NODE_PORT FIRST_NODE_PORT private Vector lt URL gt aliveNodes private Vector lt
3. ATTLIST gt gt lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt ATTLIST select gt lt ELEMENT lt ATTLIST gt lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt xml version 1 0 encoding UTF 8 gt scenario tasks topology metadata gt metadata abstract authors version title gt title PCDATA gt version PCDATA gt authors PCDATA gt abstract PCDATA gt topology slave gt slave EMPTY gt slave hostname CDATA IMPLIED name CDATA REQUIRED lt ELEMENT tasks task gt lt ELEMENT task action targets time gt lt ATTLIST task name CDATA IMPLIED ID CDATA IMPLIED time occurrence stop start gt start PCDATA gt stop PCDATA gt occurrence PCDATA gt targets slave gt targets list topology REQUIRED action method params method name gt action mode CDATA IMPLIED method name PCDATA gt method params param gt param param value param name param type gt param type PCDATA gt param name PCDATA gt param value PCDATA gt References 114 11 16 21 26 31 36 1 A Rowstron and P Druschel Pastry Scalable decentralized object lo cation and routing for large scale peer to peer systems In Proceedings 32 of the IFIP ACM International Conference on Distributed Systems Plat forms Middleware 01 nu
4. ChordImpl gt chordNodes public ChordServer PropertiesLoader loadPropertyFile aliveNodes new Vector lt URL gt chordNodes new Vector lt ChordImp1 gt bootstrapPort FIRST_NODE_PORT public DeltaMeasurement getMeasurement String metricName String measurementId String component String correlator throws RemoteException http sourceforge net projects open chord 26 12 17 22 27 32 P2PMeasurement chordMeasurement new P2PMeasurement int items if component equals FINGER_TABLE if metricName equals UNIQUE_ENTRIES for ChordImpl ch chordNodes URL peerUrl ch getURL String fingerTable ch printFingerTable if fingerTable null items 0 else items stringOccur fingerTable J String uniqueEntries new Integer items toString chordMeasurement addMeasurementUnit peerUrl toString ALIVE uniqueEntries else System err printin Unknown metric metricName else System err println Unknown component component return chordMeasurement public void setBootstrapAddress String bootstrapAddress throws RemoteException this bootstrapAddress ocsocket bootstrapAddress public void createNode throws RemoteException String bAddr this getBootstrapAddress String cAddr ocsocket this getLocalCanonicalHostName 20000 if this NODE
5. master instance e SCENARIO FILE NAME The path and name of the file containing the scenario the master instance will execute e OUTPUT_FILE_NAME The path and name of the file that will contain results provided by the getMeasurement method Note that 1 the specified path must exists before DELTA is executed and 2 if a file already exists it will not be overwritten new data will be appended at the end of it e TRACE FILE NAME The path and name of the file that will contain the trace of all actions the master has executed during the experiment This file is used for log and debug of scenarios As for the previous parameter note that 1 the specified path must exists before DELTA is executed and 2 if a file already exists it will not be overwritten new data will be appended at the end of it e ACTIONS _SEQUENCEMENT This parameter can take two values serial and paralell In the first case all actions directed to more than one 11 target will be executed sequencially with blocking calls In the second case all actions are executed concurrently 2 6 3 Slave parameters Following parameters are used by slave instances e MAX_CONNECTION_ATTEMPTS Since no distinction has to be done be tween the master and slave instances during the deployment and ex ecution phases of the code slaves instances may try to connect to the master instance before it is started an ready to listen for slaves registration This parameter as well as
6. points new Vector lt Point gt public void createPoint String label Integer x Integer y throws RemoteException 17 points addElement new Point label x y public void movePoints Integer dx Integer dy throws RemoteException 22 for Enumeration e points elements e hasMoreElements Point e nextElement move dx dy 27 public void invertPoints throws RemoteException for Enumeration e points elements e hasMoreElements Point e nextElement invert 32 public DeltaMeasurement getMeasurement String metricName String measurementId String component String correlator throws RemoteException explained in section 2 8 return null 2 5 Writing the experimentation scenario In this section we present the way an experimentation scenario can be built Since all syntaxic elements of a scenario are not illustrated here we give the DTD a scenario XML document has to follow in Listing 20 of Section 4 2 2 5 1 Overview of a scenario execution j The server Intances of the Local view of z hosting experimented remote application application Servers iane E through RMI AN Figure 1 DELTA architecture The scenario used in an experimentation is defined in a XML document which specifies what has to be done by each of DELTA instances created To clearly understand how a scenario is defined and executed one need to un derstand the DELTA architectur
7. rank pn destroy aliveNodes remove rank else System err printlin Cannot kill numberOfNodes nodes number of started nodes startedNodes public void setAlive throws RemoteException for int i 0 i lt idleThreads size i NodeStateController sc idleThreads get i sc setAlive aliveNodes addAll idleNodes idleNodes clear idleThreads clear 23 110 115 120 125 130 140 public void setIdle Integer numberOfNodes throws RemoteException if mumberOfNodes lt startedNodes for int i 1 i lt numberOfNodes intValue i int rank random nextInt aliveNodes size PastryNode pn aliveNodes get rank Environment env pn getEnvironment NodeStateController sc new NodeStateController env getSelectorManager invoke sc idleNodes add pn idleThreads add sc aliveNodes remove rank else System out println Cannot make idle numberOfNodes nodes number of started nodes startedNodes ie ae public void killA11 throws RemoteException for int i 0 i lt aliveNodes size i PastryNode pn aliveNodes get i pn destroy for int i 0 i lt idleNodes size i PastryNode pn idleNodes get i pn destroy public DeltaMeasurement getMeasurement String metricName String measurementId String component String correlator
8. reuses a lot of code elements coming from FreePastry simulator classes but it enables the control FreePastry of more that one simulator remotely Shttp freepastry rice edu 20 ou 10 20 30 40 From a Java perspective the PastryServer class implements the P2P RemoteInterface Listing 17 gives the full code of it showing thus how we integrated the simulator with DELTA The implementation of this class should be considered as an example but not as a reference since althrough it enables us to perform our tests appropriatly it may have to be reconsidered in order to be used in another context Concerning the measurements we illustrate here the need for the identi fication of components for a node we measure the number of unique entries named UNIQUE_ENTRIES of both the leafset LEAF_SET component and the routing table ROUTING_TABLE component Listing 17 The PastryServer class package fr utt era deltaappls pastry import java net import java rmi RemoteException import java util import java io import rice pastry import rice pastry socket SocketPastryNodeFactory import rice pastry standard RandomNodelIdFactory import rice pastry dist DistPastryNodeFactory import rice environment Environment import fr utt era delta import fr utt era delta p2p public class PastryServer implements P2PRemoteInstance private final static int MAX_NUMBER_OF_NODES 15 private static
9. the following one address this possibility Indeed it sets the number of times a slave has to try connecting to the master instance before giving up and exiting e CONNECTION_ATTEMPTS_TIMER This parameter must be used with the previous one It sets the number of seconds a slave waits between two connections attempts to the master instance e REMOTE_DELTA_CLASS This parameter gives the name of the class that act as an application server as described in Section 2 4 2 Note that since this class is instanciated through DELTA its constructor must not receive any parameter 2 6 4 Running the master and the slaves on the same host In case one wants to run both a master and a slave instance on the same host two different configuration files have to be provided to DELTA The only difference between these files is the add of the IS_SLAVE parameter in the slave configuration file 2 6 5 A configuration example Given the different parameters described above we give in Listing 8 an example of configuration file that can be used with the topology given in Listing 6 We assume here that the master has 192 168 0 1 as an IP address Listing 8 An example of DELTA configuration MASTER_IP 192 168 0 1 MASTER_PORT 9400 RMI_REGISTRY_PORT 1099 EXPERIMENT_ID 0123456789 ABCDEF 12 SCENARIO_FILE_NAME scenario xml OUTPUT_FILE_NAME output txt TRACE_FILE_NAME trace txt ACTIONS_SEQUENCEMENT parallel 9 MAX_CONNECTION_ATTEMPTS 3 CONNECT
10. throws RemoteException P2PMeasurement results new P2PMeasurement if metricName equals UNIQUE_ENTRIES for int i 0 i lt aliveNodes size i PastryNode pn aliveNodes get i results addMeasurementUnit pn getNodelId toString ALIVE new Integer this componentSwitch pn component toString for int i 0 i lt idleNodes size i PastryNode pn aliveNodes get i 24 160 170 180 185 190 195 200 205 results addMeasurementUnit pn getNodeId toString IDLE new Integer this componentSwitch pn component toString else System err println Unknown metric metricName Returning an empty result return results private int componentSwitch PastryNode pn String component if component equals ROUTING_TABLE return pn getRoutingTable numUniqueEntries J else if component equals LEAF_SET return pn getLeafSet getUniqueCount J else System err println Unknown component component Returning 0 return 0 private class NodeStateController implements Runnable public void run this setIdle public synchronized void setIdle try this wait catch InterruptedException e System err println Cannot make Pastry node idle e getMessage public synchronized void setAlive this notifyAll1 F 25 210
11. 2 6 Configuring Delta for the scenario execution In order to execute your scenario properly DELTA must be configured through a configuration file At runtime this file is read by both the master and slaves instances and contains parameters concerning the master instance slaves instances and both of them Following is the description of all these parameters 2 6 1 Parameters common to both the master and the slaves Following parameters are used by both the master and slave instances 10 e MASTER_IP gives the IP address of the DELTA master instance In case of a single host experiment 127 0 0 1 is supported e IS_SLAVE forces a DELTA instance to run as a slave one and this even if the host on which it is executed owns the IP address identified as MASTER_IP It is used for single host experiments for which only one of the several DELTA instances has to behave as a master See Section 2 6 4 for more information e MASTER PORT gives the TCP port number a master instance will listen on e SLAVE_PORT gives the port a slave instance will use to connect to the master If omitted a random available port is chosen e RMI_REGISTRY_PORT gives the port number the RMI registry will listen on Note that each slave instance executes a RMI registry e EXPERIMENT_ID an identifier that the master and its slaves exchanged to ensure that they are involved in the same experiment 2 6 2 Master parameters Following parameters are used by the
12. 2P application we designed the P2PRemoteInstance interface which inherits from the DeltaRemote Instance one As shown in Listing 15 this interface addresses two aspects of P2P application that are important to control in an experiment the overlay creation and the nodes life cycle management The overlay creation is controled through the createNode and setBootstrapAddress methods whose name clearly indicate their role The nodes life cycle management is operated through the four last methods setAlive setIdle kill and kil1lA11 These methods are useful to control to control for example churn in a DHT Nonetheless as for any RemoteInstance used by DELTA the body of these methods has to be implemented by the user Listing 15 The P2PRemotelnterface package fr utt era delta p2p 1 import java rmi RemoteException import fr utt era delta DeltaRemoteInstance public interface P2PRemoteInstance extends DeltaRemoteInstance 6 public void createNode throws RemoteException public void setBootstrapAddress String bootstrapAddress throws RemoteException public void setAlive throws RemoteException i public void setIdle Integer numberOfNodes throws RemoteException public void kill Integer number0fNodes throws RemoteException public void killA11 throws RemoteException Together with the P2PRemoteInstance interface we designed and im plemented the P2PMeasurement class too This class defines a dedicated contai
13. DELTA USER GUIDE Guillaume DOYEN Alain PLorx Marc LEMERCIER and Rida KHATOUN Institut Charles Delaunay ERA FRE CNRS 2848 Universit de Technologie de Troyes 12 rue Marie Curie 10000 TROYES France Contact guillaume doyen utt fr February 24 2010 v1 0 Contents 1 Introduction 2 2 User guide 3 2 1 Requirements 2 00002 eee eee 3 2 2 General method 2 2 0 0 00000 eee eee 3 2 3 Context of our example 0 3 2 4 Interfacing DELTA with the evaluated application 5 2 4 1 Defining the interface 5 2 4 2 Implementing the interface 6 2 5 Writing the experimentation scenario T 2 5 1 Overview of a scenario execution 7 2 5 2 Defining the scenario metadata 8 2 5 3 Defining the scenario topology 8 2 5 4 Defining the scenario tasks 9 2 5 5 Checking the scenario syntax 10 2 6 Configuring DELTA for the scenario execution 10 2 6 1 Parameters common to both the master and the slaves 10 2 6 2 Master parameters 2 20 0004 11 2 6 3 Slave parameters 00000000 12 2 6 4 Running the master and the slaves on the same host 12 2 6 5 A configuration example 12 2 7 Executing the experimentation 13 2 7 1 Running DELTA from the command line interface 13 2 7 2 Traces of scenario events 0 00 00084 13 2 7 3
14. ION_ATTEMPTS_TIMER 10 REMOTE_DELTA_CLASS PointServer 2 7 Executing the experimentation 2 7 1 Running Delta from the command line interface When executing an experiment with DELTA one must not start java with the application server class or any other one Indeed DELTA wraps this creation Thus the class name that has to be passed to java is the DELTA class namely fr utt era delta Delta This class can be parametered as follows f config file load the mentionned configuration file and start Delta w print warranty information and exit c print license conditions and exit Of course all classes that have to be loaded by DELTA must be given in the classpath DELTA requires two jar files that are jdom jar and log4j 1 2 9 jar Thus an execution of DELTA with an application that requires two jars appl1 jar and app12 jar could look like that java cp jdom jar log4j 1 2 9 jar delta 1 2 jar appl1 jar appl2 jar fr utt era delta Delta f delta cfg 2 7 2 Traces of scenario events In order to follow the execution of a scenario and check that it runs as expected DELTA generates a trace file that logs all events related to the executed scenario that occur Three kind of events are written in this file Scenario Start and stop times are logged Tasks Start and stop times are logged 13 Actions For each occurrence of an action a log is written It follows this convention e Actual execution time in milliseco
15. The DELTA internal logger 14 2 8 Performing measurements 000004 ee 15 2 8 1 The getMeasurement method 15 2 8 2 Integrating measurements in your code and scenario 16 2 8 3 Gathering results of measurements 18 3 Use case examples with existing P2P frameworks 19 3 1 The P2PRemotelnstance interface 19 3 2 SHTECPASEEY e soora Se gone Saa PP od GER Se lew eae Bees 20 3 3 OpenChord 3 2 0 ye tees lee ON E et sk a 26 4 Appendix 29 4 1 Full version of the point scenario 29 4 2 scenario DPD 2 20 70 64 aN E E a a a a E 32 1 Introduction Large scale evaluation is a mandatory step for the validation of any peer to peer P2P application Nonetheless while most of dedicated tools rely on simulation distributed experimentation tools are rare Experimentation in real conditions is crucial since 1 some proposals cannot be simulated and 2 it is a mandatory step towards the production of a functional imple mentation For the moment experimentation tools are mainly ad hoc ones dedicated to a specific context This situation is not satisfying because a lot of time is wasted for each experimental setup and results coming from different proposals cannot be compared DELTA is a generic environment for the large scale evaluation of any kind of distributed applications but especially for P2P ones The main features of DELTA are 1 support of large scale exp
16. This class is a simple abstract container for any type Java collection It is designed in this manner because the implementation of this class will change according to the actual kind of measurements Listing 10 The DeltaMeasurement class package fr utt era delta import java util Collection import java io Serializable public abstract class DeltaMeasurement implements Serializable protected Collection results 15 Thus in order to collect measurements one need to refine DeltaMeasurement and implement a concrete container of measurements Back to our ex ample we defined a PointMeasurement class that acts as a container for several points measurements A single measurement is coded through the PointMeasurementUnit private class Listing 11 The PointMeasurement class package fr utt era deltaappls point import java io Serializable import java util Vector import fr utt era delta DeltaMeasurement public class PointMeasurement extends DeltaMeasurement implements Serializable private static final long serialVersionUID 7306651319040545798L 12 public PointMeasurement results new Vector lt PointMeasurementUnit gt public void addMeasurementUnit String label String v 17 results add new PointMeasurementUnit label v public String toString return results toString 22 private class PointMeasurementUnit implements Serializable private stat
17. _PORT this FIRST_NODE_PORT amp amp bAddr equals cAddr this createOpenChordOverlayNetwork this getBootstrapAddress this NODE_PORT 1 else this createOpenChordPeer this getNextNodeAddress F F private void createQpenChordOverlayNetwork String peerAddress try ChordImpl chord new ChordImpl URL peerUrl new URL peerAddress chord create peerUr1 27 37 42 47 62 67 72 77 82 87 92 aliveNodes addElement peerUrl1 chordNodes addElement chord catch MalformedURLException e throw new RuntimeException e catch ServiceException e throw new RuntimeException Could not create DHT e private void createOpenChordPeer String peerAddress try ChordImpl chord new ChordImpl URL peerUrl new URL peerAddress chord join peerUrl new URL getBootstrapAddress aliveNodes addElement peerUr1l chordNodes addElement chord catch MalformedURLException e throw new RuntimeException e catch ServiceException e throw new RuntimeException Could not join DHT e public void kill Integer numberO0fNodes throws RemoteException Random random new Random Chord chord new ChordImp1 if numberOfNodes lt aliveNodes size try for int i 1 i lt numberOfNodes i int rank random nextInt aliveNodes size URL peerUrl aliveNodes get rank chord setURL peerUr1
18. alue y intValue public Integer getx return x public void setX Integer x this x xX public Integer getY return y public void setY Integer y this y y F 11 16 21 26 31 36 41 46 public String getLabel return label 2 4 Interfacing Delta with the evaluated application 2 4 1 Defining the interface Given a distributed application one need to define the actions that DELTA will perform on it These actions are defined in an interface which must inherits from the DeltaRemotelInstance one As shown in Listing 2 the latter defines a single method called getMeasurement This method is the only one which is hardcoded in DELTA All other method calls are done through introspection Details on the getMeasurement method are given in section 2 8 Listing 2 The DeltaRemotelInstance interface package fr utt era delta import java rmi Remote import java rmi RemoteException ou public interface DeltaRemoteInstance extends Remote public DeltaMeasurement getMeasurement String metricName String measurementlId String component 10 String correlator throws RemoteException Thus to startup with our example Listing 3 proposes an interface that enable the control of one or several points through DELTA It is to notice that the design of this interface is only lead by experimentation choices Nonetheless since d
19. ave name slave2 gt lt targets gt lt action mode random gt lt method name gt createPoint lt method name gt lt method params gt lt param gt lt param type gt java lang String lt param type gt lt param name gt label lt param name gt lt param value gt point lt param value gt lt param gt lt param gt lt param type gt java lang Integer lt param type gt lt param name gt x lt param name gt lt param value gt 10 lt param value gt lt param gt lt param gt lt param type gt java lang Integer lt param type gt lt param name gt y lt param name gt lt param value gt 20 lt param value gt lt param gt lt method params gt lt action gt lt task gt Now we detail the mean as well as the different ways each parameter can be used Time the time constraints are defined through a start time and stop time given in seconds and a number of occurences which is in other words the number of times task will be performed The time slicing is done with the following manner Let i be an occurence indice with ia ix stop start 0 lt i lt occurence then execution_time start a gt Targets are set through the select attribute which is either set to list or topology In the first case the list of targets is given as a child uo 10 20 30 of this tag e g Listing 7 In the second case the whole topology is concerned by the action Action repre
20. c void createNode throws RemoteException if startedNodes lt PastryServer MAX_NUMBER_OF_NODES System out println Starting node number startedNodes 1 PastryNode pn makePastryNode aliveNodes add pn startedNodestt else System err println Maximum number of nodes PastryServer MAX_NUMBER_OF_NODES is reached Cannot create a new one 22 ou ao 60 70 80 90 public void setBootstrapAddress String bootstrapAddress throws RemoteException if bootstrapAddress startsWith localhost try bootstrapAddress InetAddress getLocalHost getHostName bootstrapAddress substring bootstrapAddress indexOf catch UnknownHostException e System err println Cannot convert localhost to the actual host name System exit 1 bootaddr bootstrapAddress substring 0 bootstrapAddress indexOf bootport Integer value0f bootstrapAddress substring bootstrapAddress indexOf 1 intValue bindport Integer valueOf bootstrapAddress substring bootstrapAddress indexOf 1 intValue System out println Setting bootstrap address to bootaddr port bootport public void kill Integer number0fNodes throws RemoteException if mumberOfNodes lt startedNodes for int i 1 i lt numberOfNodes intValue i int rank random nextInt aliveNodes size PastryNode pn aliveNodes get
21. chord leave aliveNodes remove rank catch ServiceException e e printStackTrace else System err printlin Cannot kill numberOfNodes nodes number of started nodes aliveNodes size public void killA11 throws RemoteException Chord chord new ChordImp1 try for URL peerUrl aliveNodes chord setURL peerUr1 chord leave 28 97 102 107 112 117 122 127 132 142 147 catch ServiceException e e printStackTrace aliveNodes clear public void setAlive throws RemoteException This method is not used with our OpendChord connector public void setIdle Integer arg0 throws RemoteException This method is not used with our OpendChord connector F private String getBootstrapAddress return bootstrapAddress private String getNextNodeAddress String result URL KNOWN_PROTOCOLS get URL SOCKET_PROTOCOL getLocalCanonicalHostName NODE_PORT return result private String getLocalCanonicalHostName String result null try result InetAddress getLocalHost getCanonicalHostName catch UnknownHostException e e printStackTrace return result private int stringOccur String text String string return regexOccur text Pattern quote string F private int regexOccur String text String regex Matcher matcher Patt
22. e as depicted on Figure 1 At runtime each DELTA instance is executed in a different JVM Each instance plays a role one is the master while others are slaves The master is in charge of solely 5 Java Virtual Machine 37 executing the scenario while slaves instantiate the application server and thus actually host the evaluated application From a scenario perspective this architecture has the following consequence the master never appears in a scenario and targets are the slave instances Following is the description of each point a scenario has to define It follows our Point example The full version of the scenario can be found in Listing 19 of section 4 1 2 5 2 Defining the scenario metadata A scenario is composed of three parts The first part gives metadata con cerning the scenario scenario author scenario name a description a date a version This information is used to generate the header of results file easing thus the correlation between a scenario and the obtained results An example of scenario metadata is given in Listing 5 Listing 5 Metadata of a scenario lt metadata gt lt title gt Points scenario i lt title gt lt version gt version 1 12 10 2007 lt version gt lt authors gt Marc LEMERCIER lt authors gt lt description gt Affiche Points lt description gt lt metadata gt 2 5 3 Defining the scenario topology The second part of a scenario is the definition of the expe
23. eps but we explain how to perform measurements with DELTA in a dedicated section 2 3 Context of our example The example we use along this user guide is based on objects standing for points Here a Point represents the individual element of the distributed application we want to experiment In a concrete experimenation case it could a peer an agent or any other kind of distributed piece of code Listing 1 gives the source code of the Point class A Point is defined through two coordinates and a label For each of these attributes getter and setter are defined Tranformation methods namely move and invert perform operations on attributes and finally the distance method returns http java sun com http ant apache org the distance of the Point from the origin This code was designed to simple since this guide does not focus on the evaluated application but rather on its integration in DELTA Listing 1 The Point class package fr utt era deltaappls point public class Point private Integer x y private String label public Point String label Integer x Integer y this x xX this y y this label label public void invert Integer i x Riera Ses y i public void move Integer dx Integer dy x dx y dy public double distance double d Math sqrt Math pow x 2 Math pow y 2 return d public String toString return Point label x intV
24. eriments 2 complete independence from the evaluated ap plication 3 the repeatability of experiments and 4 the definition of P2P standard actions and measurements This guide is intended to show how to get started with DELTA Section 2 is the actual user guide It uses a single example built around the Point class which simulates a distributed application It first gives the general method one has to follow for each new experiment Then it details each step Section 3 presents use case examples of DELTA Specificaly it focuses on two java based implementations of DHT that are FreePastry and OpenChord http delta utt fr Finally Section 4 gives full listings of elements that are referenced in the user guide 2 User guide 2 1 Requirements Entirely written in Java DELTA supports both Windows and Linux operat ing systems To use a compiled version of DELTA Java JDK 1 6 or later is required To compile it Ant version 1 6 5 or later is required too 2 2 General method In order to use DELTA as experimentation support one has to follow steps described below 1 Defining the interface between DELTA and the evaluated application 2 Implementing the interface 3 Writing the experimentation scenario 4 Configuring DELTA for the scenario execution 5 Executing the experimentation In the following we explain each of these steps with a simple example We chose not too include measurements aspects in these st
25. ern compile regex matcher text int occurence 0 while matcher find occurencett return occurence 4 Appendix 4 1 Full version of the point scenario 29 162 167 172 182 187 192 Listing 19 Full version of the point scenario lt xml version 1 0 encoding UTF 8 gt lt DOCTYPE scenario SYSTEM scenario dtd gt lt scenario gt lt metadata gt lt title gt Points scenario 1 lt title gt lt version gt version 1 12 10 2007 lt version gt lt authors gt Marc LEMERCIER lt authors gt lt description gt Affiche Points lt description gt lt metadata gt lt topology gt lt slave name slavel hostname slavel utt fr gt lt slave name slave2 gt lt slave name slave3 gt lt topology gt lt tasks gt lt task ID 1 name CreatePoints gt lt time gt lt start gt 1 lt start gt lt stop gt 2 lt stop gt lt occurrence gt 2 lt occurrence gt lt time gt lt targets select list gt lt slave name slavei gt lt slave name slave2 gt lt targets gt lt action mode random gt lt method name gt createPoint lt method name gt lt method params gt lt param gt lt param type gt java lang String lt param type gt lt param name gt label lt param name gt lt param value gt point lt param value gt lt param gt lt param gt lt param type gt java lang Integer lt param
26. ic final long serialVersionUID 6931047266354749278L 27 private String name private String value public PointMeasurementUnit String n String v name n value v 32 public String toString return new String name t value 2 8 2 Integrating measurements in your code and scenario As for any method DELTA calls in a scenario the body of the getMeasurement method has to be written by the user Listing 12 gives an example of im plementation that for each point on the host collects its distance from the 16 origin Note that in this case we do not specify a target component nor a correlator Listing 12 An implementation example of the getMeasurement method public DeltaMeasurement getMeasurement String metricName String measurementId String component String correlator throws RemoteException PointMeasurement pm new PointMeasurement if metricName equals DISTANCE for Enumeration lt Point gt e points elements e hasMoreElements Point p e nextElement String distance Double toString p distance pm addMeasurementUnit p getLabel distance else System err printin Unknown metric metricName return pointMeasurement Listing 13 Performing measurements in a scenario lt task ID 2 name measurement gt lt time gt lt start gt 5 lt start gt lt stop gt 9 lt stop gt lt occurrence gt 2 lt
27. int bindport 5009 private static String bootaddr null private static int bootport 5009 private PastryNodeFactory factory private NodeIdFactory nidFactory private int startedNodes private Vector lt PastryNode gt aliveNodes private Vector lt PastryNode gt idleNodes private Vector lt NodeStateController gt idleThreads private Random random private Date date private Environment env public PastryServer env new Environment date new Date random new Random date getTime 21 ou 10 20 30 40 nidFactory new RandomNodeldFactory env try factory new SocketPastryNodeFactory nidFactory bindport env F catch IOException e System err println e getMessage System exit 1 aliveNodes new Vector lt PastryNode gt idleNodes new Vector lt PastryNode gt idleThreads new Vector lt NodeStateController gt startedNodes 0 protected NodeHandle getBootstrap InetSocketAddress addr null addr new InetSocketAddress bootaddr bootport NodeHandle bshandle DistPastryNodeFactory factory getNodeHandle addr return bshandle private PastryNode makePastryNode NodeHandle bootstrap getBootstrap PastryNode pn factory newNode bootstrap synchronized pn while pn isReady try pn wait catch InterruptedException e System out println e return pn publi
28. mber 2218 in LNCS pages 329 350 Springer Verlag 2001 I Stoica R Morris D Karger M F Kaashoek and H Balakrish nan Chord A scalable peer to peer lookup service for internet appli cations In Proceedings of the ACM Conference on Applications Tech nologies Architectures and Protocols for Computer Communication SIGCOMM 01 pages 149 160 ACM Press 2001 33
29. n order to run user defined meth ods that take part of a experimentation scenario Nonetheless we have kept away the one which is the most important getMeasurement This method allows a user to perform any kind of measurements in its application and to collect them in the output file as defined in the DELTA configuration file on the master instance The getMeasurement method is the only one whose definition is hard coded in DELTA cf Listing 2 Nonetheless we defined it to be generic enough so that can be used in any context Parameters of the method are metricName A textual string which represents the name of the metric For example in the application case of this guide it could be DISTANCE measurementid A string used to identify a measurement independantly from its name This allow the user to correlate results coming from different hosts but taking part of the same measurement component A string that identify the target component of the application This parameter is usefull because in an application the same metric name may have to be used on different parts of an application correlator A user defined string that is passed to the application It is intended to be used when measurements are themselves distributed and thus need to be correlated before being collected in the output file Now concerning the return of the method Listing 2 shows that it is an object of class DeltaMeasurement whose code is given in Listing 10
30. nds e Expected execution time in milliseconds as specified in the sce nario e Task name e Method name e Target e Execution duration in microseconds Listing 9 is an example of trace file for the execution of the task depicted in Listing 7 Listing 9 An example of scenario trace Title Points scenario 1 Author s Marc LEMERCIER Execution date Thu Apr 24 18 44 13 CEST 2008 Heap memory init O 0K used 701240 684K committed 5177344 Non heap memory init 33751040 32960K used 14738144 14392K o Scenario Points scenario 1 started 1000 Task CreatePoints started 1004 1000 CreatePoints createPoint slave2 1621523 micros 1503 1500 CreatePoints createPoint slavel 4166597 micros 1997 Task CreatePoints ended 2005 Scenario Points scenario 1 ended 2 7 3 The Delta internal logger To monitor the way DELTA operates a logger is defined for each DELTA component This logger is configured through a file whose name is hardcoded in DELTA Thus at runtime in the root folder of your experiment the file logger cfg must exist as well as a log folder in which DELTA will write an internal log file Future versions of DELTA will probably remove this limitation but for the moment one must deal with this constraint in order to let DELTA working properly 14 12 17 2 8 Performing measurements 2 8 1 The getMeasurement method Up to this point we saw how to use DELTA i
31. ner for P2P measurements that integrates the state of a node alive idle or dead according to life cycle we defined The code of this class is given in Listing 16 19 Listing 16 The P2PMeasurement class package fr utt era delta p2p import import import public java util Vector java io Serializable fr utt era delta DeltaMeasurement class P2PMeasurement extends DeltaMeasurement implements Serializable private static final long serialVersionUID 83027390510991422L public P2PMeasurement results new Vector lt P2PMeasurementUnit gt public void addMeasurementUnit String nId String s String v J results add new P2PMeasurementUnit nId s v public String toString return results toString private class P2PMeasurementUnit implements Serializable private static final long serialVersionUID 2219465867290080731L private String nodeld private String state private String value public P2PMeasurementUnit String nId String s String v nodelId nid state s value v public String toString return new String nodeId t state t value 3 2 The original goal which led us to design and implement DELTA is the lack of a such a tool in FreePastry the Java implementation of the Pastry DHT 1 Althrough FreePastry provides a simulator from our knowledge it is limited to a single JVM Thus our Pastry server class
32. riment topology The latter is used to let the master knwo the number of expected slaves in the experiment and for each slave it gives a symbolic name used in the tasks and optionnaly associate it with a specific hostname To illustrate this definition consider the topology represented in Listing 6 executed by hosts named slavel utt fr slave2 utt fr and slave3 utt fr Since slave slavel is explicitely linked the host named slavel1 utt fr in the topology definition actions targeted to slavel will be executed by slavel utt fr Now concerning slave2 and slave3 depending of the registration order they will be indifferently attached to slave2 utt fr or to slave3 utt fr Listing 6 Topology of a scenario lt topology gt lt slave name slavel hostname slavei utt fr gt lt slave name slave2 gt lt slave name slave3 gt lt topology gt uo 2 5 4 Defining the scenario tasks The third part is a set of tasks to be executed Each task is defined through three parameters that are the action performed the target slaves and the time constraints Listing 7 gives an example of action that illustrates these settings Listing 7 Example of a task lt task ID 1 name CreatePoints gt lt time gt lt start gt 1 lt start gt lt stop gt 2 lt stop gt lt occurrence gt 2 lt occurrence gt lt time gt lt targets select list gt lt slave name slavei gt lt sl
33. sents the full definition of the method call with the method name and for each method parameter its name its type and its value The mode attribute tells which targets of the task will execute the action Set to random for each occurrence only one randlomly chosen target will perform the action Set to all all the task targets will perform it N B The value parameter of a method call has sometime to be the hostname of a slave Since such a name cannot be a priori determined due to the dynamic bind of slaves names to hostnames an escaping sequence enables DELTA to dynamically replace a slave name by the hostname at runtime This escape sequence is bound with and caracters For example topology given in Listing 6 slave1 can be dynamically replaced by slave1 utt fr at runtime by writing slave1 as a parameter value This functionnality is especially interesting in P2P experiments for example to set bootstrap addresses 2 5 5 Checking the scenario syntax At runtime when DELTA loads the experiment scenario it checks the sce nario syntax as defined in the DTD given in Listing 20 of Section 4 2 Thus a file named scenario dtd containing the scenario DTD must exist in the folder of the executed scenario Otherwise DELTA will stop and print a related error message Future versions of DELTA will probably remove this limitation but for the moment one must deal with this constraint in order to let DELTA working properly
34. t e Target slave name e Component name e Metric name e Measurement value as specified in the toString methods of the mea surement class and measurement unit class Following is an example of output file for the measurement task de scribed in Listing 13 We assume that this task is integrated in the same scenario that contains the createPoints task too cf Listing 7 Thus slavei has no Point instance and returns an empty result when performing a measurement Listing 14 An example of output file Title Points scenario 1 Author s Marc LEMERCIER Execution date Wed Jul 16 11 40 26 CEST 2008 5000 5023 5055 0x0001 1 slavei null DISTANCE 5000 5023 5055 0x0002 1 slave2 null DISTANCE point 22 36 5000 5023 5055 0x0002 1 slave3 null DISTANCE point 22 36 7000 7021 7022 0x0002 2 slavei null DISTANCE 7000 7021 7022 0x0002 2 slave2 null DISTANCE point 22 36 7000 7021 7022 0x0002 2 slave3 null DISTANCE point 22 36 18 33 12 3 Use case examples with existing P2P frameworks In this section we give use examples of DELTA with existing frameworks namely FreePastry and OpenChord two Java based implementations of re spectively the Pastry 1 and Chord 2 DHT Before presenting these use we present a generic interface we designed in order to refine DELTA in the context of P2P applications 3 1 The P2PRemotelInstance interface In order to capture all the aspects specific to a P
35. thod params gt lt action gt lt task gt lt task ID 2 name measurement gt lt time gt lt start gt 5 lt start gt lt stop gt 9 lt stop gt lt occurrence gt 2 lt occurrence gt lt time gt lt targets select topology gt lt action mode all gt lt method name gt getMeasurement lt method name gt lt method params gt lt param gt lt param type gt java lang String lt param type gt lt param name gt metricName lt param name gt lt param value gt DISTANCE lt param value gt lt param gt lt param gt lt param type gt java lang String lt param type gt lt param name gt measurementId lt param name gt lt param value gt 0x0001 lt param value gt lt param gt lt param gt lt param type gt java lang String lt param type gt lt param name gt component lt param name gt lt param value gt null lt param value gt lt param gt lt param gt lt param type gt java lang String lt param type gt lt param name gt correlator lt param name gt lt param value gt null lt param value gt lt param gt lt method params gt lt action gt 31 64 69 74 79 84 89 94 99 104 109 lt task gt lt tasks gt lt scenario gt 4 2 scenario DTD Listing 20 DTD of a scenario lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt
36. type gt lt param name gt x lt param name gt lt param value gt 10 lt param value gt lt param gt lt param gt lt param type gt java lang Integer lt param type gt lt param name gt y lt param name gt lt param value gt 20 lt param value gt lt param gt lt method params gt lt action gt lt task gt lt task ID 2 name measurement gt lt time gt lt start gt 5 lt start gt lt stop gt 9 lt stop gt lt occurrence gt 2 lt occurrence gt lt time gt lt targets select topology gt lt action mode all gt lt method name gt getMeasurement lt method name gt 30 9 14 19 24 29 34 39 44 49 lt method params gt lt param gt lt param type gt java lang String lt param type gt lt param name gt metricName lt param name gt lt param value gt DISTANCE lt param value gt lt param gt lt param gt lt param type gt java lang String lt param type gt lt param name gt measurementId lt param name gt lt param value gt 0x0001 lt param value gt lt param gt lt param gt lt param type gt java lang String lt param type gt lt param name gt component lt param name gt lt param value gt null lt param value gt lt param gt lt param gt lt param type gt java lang String lt param type gt lt param name gt correlator lt param name gt lt param value gt null lt param value gt lt param gt lt me
37. uring an experiment all methods calls are performed through RMI each method must throw the java rmi RemoteException Listing 3 The PointRemotelnstance interface package fr utt era deltaappls point import fr utt era delta DeltaRemoteInstance import java rmi RemoteException public interface PointRemoteInstance extends DeltaRemoteInstance Remote Method Invocation public void createPoint String label Integer x Integer y T throws RemoteException public void movePoints Integer dx Integer dy throws RemoteException public void invertPoints throws RemoteException 12 2 4 2 Implementing the interface Once the interface is defined the next step consists in implementing it in what we call a server We use this term because this class will create host and let be reachable the application here a point Thus the class PointServer contains a collection of Points here a vector and performs operations on it through the methods defined in the PointRemoteInstance instance As for previous section we do not give here explanation concerning the getMeasurement method which will be detailed later in this document Listing 4 The PointServer class package fr utt era deltaappls point import fr utt era delta DeltaMeasurement import java rmi RemoteException import java util public class PointServer implements PointRemoteInstance private Vector lt Point gt points public PointServer 12
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