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JXTA: Tech Brief

JXTA: Tech Brief

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JXTA: Tech Brief

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  1. JXTA: Tech Brief Dan Berger, Suvidhean Dhirakaosal, Essia Hamouda, Demetris Zeinalipour CS 202 Spring 2003

  2. Outline • Problem Statement/Motivation • Architecture Overview • Experiments/Demonstrations • Conclusions

  3. Motivation • Existing P2P solutions have had rapid adoption and success – so why build another? • JXTA attempts to address 3 key “shortcomings” of typical P2P systems: • Interoperability • Platform Independence • Ubiquity

  4. Interoperability • Gnutella for file sharing, ICQ/AIM/Yahoo/Jabber/MSN for instant messaging • But none of them can talk to each other. • This has led to the development of apps like Gaim (linux) and Trillian (windows) that provide a single front-end to multiple protocols. • JXTA aims to standardize at the protocol level.

  5. Platform Independence • JXTA is “independent” of programming language, operating system, and networking platform. • The core of JXTA are protocol definitions, not API’s.

  6. Ubiquity • JXTA was designed to be scalable to any device with a “network heartbeat” – cited examples are: • Sensors • Consumer electronics (toasters, cell phones) • PDAs • Etc.

  7. The Grand Vision

  8. Enough Buzzwords, Already • JXTA proposes a set of services to enable building a securable logical overlay network linking “peers:” • Peer Discovery • Peer Resolution • Rendezvous • Pipe Binding • Endpoint Routing

  9. Gratuitous Architecture Picture

  10. Just the Facts • Each node in the JXTA network • has a “peer id” - a “globally” unique ID (UUID) • Urn:jxta:idform3-31:08:66:42:67:::91:24::73 • Is Autonomous and may operate independently of all peers • Peers (self)organize into peer groups – loosely hierarchical. • All peers belong to the “World” group. • Peers and services are advertised with advertisements (XML documents)

  11. Advertisements • Used to describe peers, peers groups, pipes, content, services and resources • Used to pass info between peers • Are presented in XML • Peer Adv. • Peer group Adv. • Module Class Adv. • Module Spec. Adv. • Module Implementation Adv.

  12. Discovery Query <xs:element name="DiscoveryQuery" type="jxta:DiscoveryQuery"/> <xsd:simpleType name="DiscoveryQueryType"> <xsd:restriction base="xsd:string"> <!-- peer --> <xsd:enumeration value="0"/> </xsd:restriction> </xsd:simpleType> <xs:complexType name="DiscoveryQuery"> <xs:sequence> <xs:element name="Type" type="jxta:DiscoveryQueryType"/> <xs:element name="Threshold" type="xs:unsignedInt" minOccurs="0"/> <xs:element name="Attr" type="xs:string" minOccurs="0"/> <xs:element name="Value" type="xs:string" minOccurs="0"/> <!-- The following should refer to a peer adv, but is instead a whole doc for historical reasons --> <xs:element name="PeerAdv" type="xs:string" minOccurs="0"/> </xs:sequence> </xs:complexType>

  13. Discovery • LAN-based (broadcast) • Invitation (in or out of band, via an advertisement) • Cascaded (controlled view across discovered peers) • Rendezvous (napster-esqe)

  14. Resolution • In general – a service that resolves advertisements into endpoints. • JXTA ships with one implementation – “Rendezvous” – in which hosts serve as switchboards for messages. • More complex/decentralized resolvers are possible, but not specified/provided.

  15. Pipes • Pipes are unidirectional communication channels. • Peers can host input pipes (incoming messages), or output pipes (outgoing messages). • Pipes can be chained to link peers across multiple logical hops, and can be one-to-many. • Pipes are bound to peer ids, not IP address.

  16. Pipe

  17. Routing • Allows peers to discover routes for reaching a peer which can not be directly connected to. • I.e. behind a firewall, NAT device, different network platform, etc.

  18. Experiments

  19. Required Components • has Java and C implementations of the core protocols. • The C version is based on the APR (apache portable runtime) and trails behind the JAVA version in terms of functionality and ease of use. • For Java – requires the J2SE JDK

  20. Installation & Configuration • Install a JRE/JDK (e.g. Sun 1.3.1_1) • Download the latest JXTAInst_VM.exe InstallAnywhere installer (JXTA v2.0) (4.71MB) (Or download JXTAInst.exe which contains VM) • Download tutorials/code from

  21. JXTA Jars • JXTA’s core uses 13 other JAR files like Jetty portable Web/Servlet Server, Log4J apache’s generic logging API. • Directory Structure so far • /InstantP2P -> A “full-fledged” instant P2P application • /lib -> The JAR Files • /lib/jxta.jar -> Contains the JXTA Programming API • /Shell -> Command-line Interface to JXTA • /tutorials -> Tutorials that we downloaded individually

  22. Step 0: Source/Compiling“Creating a PeerGroup” java -classpath jxta.jar;OTHER_JAR_FILES.jar; Hello import net.jxta.peergroup.*; import*; import*; public class Hello { static PeerGroup netPeerGroup = null; static DigestTool digestTool = new DigestTool(); public static void main(String args[]) { try { netPeerGroup = PeerGroupFactory.newNetPeerGroup(); System.out.println("Hello from JXTA group " +netPeerGroup.getPeerGroupName() ); System.out.println(" Group ID = " +netPeerGroup.getPeerGroupID().toString()); System.out.println(" Peer name = " + netPeerGroup.getPeerName()); System.out.println(" Peer ID = " + netPeerGroup.getPeerID().toString()); }catch(Exception e){e.printStackTrace();} } }

  23. Step 1 : Running the code 1 2 Now a .jxtadirectory is created on disk which contains all settings On the next run we only fill in an authentication box 3 4

  24. Step 2 : JXTA Sockets! (as of v2.0) • JXTA introduces a Socket API which is similar to the familiar sockets. • The Socket API attempts to make JXTA Pipe programming easier. (JxtaSocket is a bi-directional Pipe) • JxtaServerSocket: Server socket that waits for connections from clients. • JxtaSocket: Socket class used to create the I/O streams for both clients and servers.

  25. Step 3 : JXTA Sockets Example • In this example we use to types of “advertisement” Discovery Services: • LAN-based discovery: Local broadcast over the subnet. ( to • Works if peers are within the same subnet or if multicast-enabled routers are connecting the peers • Discovery via rendezvous points A peer at a well-known address has the task of knowing and disseminating locations of peers. • Works if peers are fire-walled in which case direct connection between peers is not feasible.

  26. Step 3 : JXTA Sockets Example Rendevouz Service 6 a)connect, b)receive msg, c) send msg back Server Client FIREWALL 5 a)connect, b)receive msg, c) send msg back The Server I want 4 My ServerSocket (multicast channel) to connect to is 2 ID is uuid...BC uuid...BC 3 read the text file 1 read the text file socket.adv <!DOCTYPE jxta:PipeAdvertisement> <jxta:PipeAdvertisement xmlns:jxta=""> <Id> urn:jxta:uuid-59616261646162614A757874614D504725184FBC </Id> <Type> JxtaUnicast </Type> <Name> socket example </Name> </jxta:PipeAdvertisement>

  27. JXTA Sockets Code Snippets Server (main snippets) // create, and Start the default jxta NetPeerGroup PeerGroupnetPeerGroup = PeerGroupFactory.newNetPeerGroup(); // Read file from disk FileInputStream is = new FileInputStream("socket.adv"); // Generate Pipe Advertisment PipeAdvertisement pipeAdv = (PipeAdvertisement)AdvertisementFactory. new Advertisement(is); // Launch ServerSocket JxtaServerSocket serverSocket = new JxtaServerSocket(netPeerGroup, socEx.pipeAdv); // if client connects, spawn two new Threads (input/output). JxtaSocket socket = serverSocket.accept(); OutputStream out = socket.getOutputStream(); InputStream in = socket.getInputStream(); // send a message String msg = “Hello JXTA”; out.write(msg.getbytes()); // receive message back, 0, bufsize);

  28. JXTA Sockets Code Snippets Client (main snippets) // create, and Start the default jxta NetPeerGroup PeerGroupnetPeerGroup = PeerGroupFactory.newNetPeerGroup(); // Read file from disk FileInputStream is = new FileInputStream("socket.adv"); // Generate Pipe Advertisment PipeAdvertisement pipeAdv = (PipeAdvertisement)AdvertisementFactory. new Advertisement(is); // Launch Socket along with 2 new Threads (input/output). JxtaSocket socket = new JxtaSocket(netPeerGroup, pipeAdv); OutputStream out = socket.getOutputStream(); InputStream in = socket.getInputStream(); // receive message read =, 0, bufsize); System.out.println(">> " + new String(inbuf)); // send message back out.write(inbuf, 0, read);

  29. JXTA Sockets Code Snippets Server acting also as Rendezvous Client connecting to Rendezvous

  30. Conclusions

  31. Ongoing JXTA Projects Full list available at : Gnougat: A Fully decentralized file caching RossetChat: Localized JXTA Peer Text Messaging Radiojxta: delivering audio content over JXTA networks P2Pconference: A tool to conduct remote, text-based conferences InstantP2P: To be interactively displayed.