Jxta--java Peer-to-peer Network Programming Technology (introductory article)

1 . Preface

RecentP2p（Peer-to-peer) has become a hot spot on the internet.Peer-to-peer is an application model of the Internet, meaning that any device on the network (including mainframes,PCs ,PDAs, mobile phones, set-top boxes, and so on) can connect and collaborate equally directly. Compared to the current mainstream Internet application Mode client/server or client/service ,Peer-to-peer has its own distinct characteristics and advantages. (This is where I'm fascinated by it.) Oh...... J)

with peer-to-peer technology, the Internet does not need a large server, which for some industries (especially online games), is very "lucky"! Because peer-to-peer technology is very convenient to achieve you only small money can achieve the desired effect. (Is it a heartbeat?) Oh...... J)

some common peer-to-peer apps: Chat programs, games (especially online games), file sharing, collaborative work, and whiteboards.

Of course,peer-to-peer Networks should also have the following characteristics:

①      p2p system is easy to find and connect each other, Communicate with each other.

② Platform independence: p2p system should be designed to be independent of programming languages such as c,java windows unixtcp/ip bluetooth

③ :peer-to-peer systems can be run on any device with digital processing capabilities.

2 . What's JXTA?

       First of all, jxtap2pp2p

Second,JXTA is a platform for Peer-to-peer application development. At present,JXTA first introduced the JAVA based reference implementation.

It consists of three layers: as shown in Figure 1-1 :

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Figure 1-1 Hierarchy of JXTA

The first floor isJxtaCore layer, which contains the core functionality required by the service, includingPeer, peer groups,PeerFoundPeerCommunicationPeerMonitoring and related security primitives; the second tier is the service layer, which provides access to thejxta protocol interface, including for p2p network is not required, but very common features such as find, share , index, code caching, and content caching mechanisms; The third tier is the application layer, which uses services to access jxta Network and jxta provides the function, Including the application jxta service developed a complete p2p applications such as Myjxta,jxta-cad

Here is a brief introduction to some of the concepts of JXTA:

3 . Some concepts of JXTA

Peer (PEER): a virtual point of communication. A user can have multiple Peer, and a single computer or device can have multiple Peer.

Peer Group (peer group): a way of organizing Peer and publishing specific services within a group. Can be created, joined, and exited; In a group, you can update the relationship of a group member.

       Pipe (Pipeline): peerpeer

       advertisement (AD): a xmljxta peerjxtajxtautf-8

Message (message): There are two ways to process messages: ① uses XML format; ② uses binary format.

Rendezvous Peer (Rendezvous point): A Peer that can handle requests from other Peer . You can also delegate a request to another collection point.

       Router Peer peer): a support peerpeer

       Gateway Peer peer): a peer rendezvous Peer The difference is that it is used in peerrendezvous Peer

All right, so many things, even I was a little dizzy. J hehe ... Let's start with an example to familiarize yourself with:

4 . Download and install JXTA

Software Address:jxta.org/">http://www.jxta.org2003-12-15 updated stable version. It offers several platforms, depending on your operating system to select the jxta jxta tool, can be http:// Www.apache.org download. One more note is that you also have to install jdk1.3.1jdk1.4 version.

Here's a little bit about configuration:

Run for the first timeJxtaProgram,JxtaThe configuration tool is automatically displayed. InBasic settingspage, fill in the name you think is cool, show yourPeer Name。 ClickOk。 The next interface enters a secure user name (Secure Username) and Password (Password), and then inExperienced Users onlypage, fill in yourIpAddress and Port,tcp The default port is 9701, The default port is 9700+" button. The meaning of the check box is clear at a glance. Of course you can also click download Relay and Rendezvous Liststcp and http Rendezvous list, and gateway list.

If you have a firewall, be sure to select the use a relay (Required if behind Firewall/nat) check box.

Congratulations, you can feel and experience the JXTA program now. J

5 . Hello JXTA 's simple program

Program Source code:

Hellojxta.java

Import java.io. InputStream;

Import Net. JXTA.peergroup.PeerGroup;

Import Net. JXTA.peergroup.PeerGroupFactory;

Import Net. JXTA.exception.PeerGroupException;

public class Hellojxta {

Public static void main(String args[]) {

System.out.println("Starting JXTA ...");

Hellojxta MyApp = new Hellojxta();

Myapp.startjxta();

System.exit(0);

}

Public void Startjxta() {

Peergroup pg = null;

try {

pg = Peergroupfactory.newnetpeergroup();

Catch (peergroupexception e) {

System.out.println("Fatal Error:group creation Failure");

E.printstacktrace();

system.exit(1);

}

System.out.println("Hello jxta!:)" );

System.out.println("Group name =" +pg.getpeergroupname());

System.out.println("Group ID =" +pg.getpeergroupid(). ToString());

System.out.println("Peer name =" +pg.getpeername());

System.out.println("Peer ID =" +pg.getpeerid(). ToString());

System.out.println("Peer baseclass =" +pg.reftcpprotospecid.getbaseclass());

}

}

Note, however, that this program uses the Jxta.jar file at compile time, so we compile the program:

D:>javac