Peer-to-Peer with Centralized Index (P2P-CI) System

A P2P-CI system in which peers can download RFC files from another active peer with TCP connection.

Internet protocol standards are defined in documents called “Requests for Comments” (RFCs).

There is a centralized server which keeps information about active peers and maintains an index of RFCs available at each active peer.

When peers join the P2P-CI system, it will register itself at the server and provide information about RFCs that it makes available to other peers.

When a peer wishes to download a specific RFC, it will get a list of other peers who have that RFC by requiring the central server.

The TCP connection between a peer and central server is long-lived, and the TCP connection between peers is short-lived.

Features

• Join/Leave P2P System
• Add RFCs to central server
• Look up a RFC from central server
• List all RFCs in P2P System
• Download a RFC from other peer

Build from source

Prerequisites

Install Java & Maven

• JDK 8+
• Maven version 3.x

Download the source

git clone https://github.com/weiranfu/P2P-system.git

cd P2P-system/

Build the source

mvn clean install

How to run

Run Server:

$java -cp target/P2PSystem-1.0-SNAPSHOT.jar P2PSystem.P2PSystemServer

Run Client:

$java -cp target/P2PSystem-1.0-SNAPSHOT.jar P2PSystem.P2PSystemClient

RFC files

• Local RFCs are stored under /localRFCs/
• RFCs downloaded from other peers are stored under /downloadedRFCs/
• The format of RFC name is rfcxxx.txt

Protocols

The protocols used in P2P-CI system is a simplified version of HTTP protocol.

• Protocol among peers:

  query:

     method <sp> RFC number <sp> version <cr> <lf> 
     header field name <sp> value <cr> <lf>
     header field name <sp> value <cr> <lf>
     ...
     <cr> <lf>
  

  response:

     version <sp> status code <sp> phrase <cr> <lf> 
     header field name <sp> value <cr> <lf>
     header field name <sp> value <cr> <lf>
     ...
     <cr> <lf> 
     data
     <cr> <lf>
  

• Protocol between server and peer:

  query:

    method <sp> RFC number <sp> version <cr> <lf> 
    header field name <sp> value <cr> <lf>
    header field name <sp> value <cr> <lf>
    ...
    <cr> <lf>
  

  response:

    version <sp> status code <sp> phrase <cr> <lf>
    <cr> <lf>
    RFC number <sp> RFC title <sp> hostname <sp> upload port number<cr><lf> 
    RFC number <sp> RFC title <sp> hostname <sp> upload port number<cr><lf>
    ...
    <cr><lf>
  

  Four methods are supported
  • ADD, to add a locally available RFC to the server’s index
  • LOOKUP, to find peers that have the specified RFC
  • LIST, to request the whole index of RFCs from the server
  • GET, to download a specific RFC from other peer

  Four status codes are supported
  • 200 OK
  • 400 Bad Request
  • 404 Not Found
  • 505 P2P-CI Version Not Supported

License

MIT