Chord

An Go implementation of Chord P2P Protocol

Install

Get the package

$ go get github.com/wang502/chord

Import the package

import "github.com/wang502/chord"

Usage

Configure

Add a config.json file in your source folder

{
  "Host": ,
  "HashBits": ,
  "NumNodes": ,
}

• Host: the host name of ip of the local server that wants to join the Chord ring
• HashBits: the number of bits in the hash bits to apply consistent hashing.
• NumNodes: the max number of nodes to participate in Chord ring. 2^(HashBits) = NumNodes

Initialize config

• Initialize default congiguration with HashBits=3 NumNodes=8 by passing only the host name

host = "localhost:3000"
config := chord.DefaultConfig(host)

Initialize Chord server

import (
    "github.com/gorilla/mux"
	"github.com/wang502/chord"
)

transporter := chord.NewTransporter()
chordServer := chord.NewServer("chord1", config, transporter)
transporter.Install(server, mux.NewRouter())

Chord servers can communicate with each other using an HTTP transporter. And after transporter installs chord server, following url paths are mapped to respective handlers:

• "/findSuccessor": path to handle incoming request to find successor of an given id
• "/getPredecessor": path to return the predecessor of this chord node
• "/getSuccessor": path to return the successor of this chord node
• "/getFingerTable": path to return the finger table of this chord node
• "/notify": path to handle the notify request
• "/join": path to handle a join request sent from a Chord server
• "/start": path to start this Chord server
• "/stop": path to stop this Chord server

Join Chord ring

By knowing the host name of another server that is participating in the Chord ring, this server can join the Chor ring as well This example joins a Chord ring consisting a http://localhost:4000 host.

err := chordServer.Join("http://localhost:4000")
if err != nil {
    // handle error
}

Find successor

succReq := NewFindSuccessorRequest(id, host)
succResp, err := chord.FindSuccessor(succReq)