This project is intended to become a robust Scala implementation of Chord, a protocol and algorithm for a peer-to-peer distributed hash table.

This repo currently contains two modules - core and demo.

The core module is being developed as a reusable Chord library, responsible for maintaining a node's location within a Chord overlay network. This approach, which is based on the architecture described in the Chord paper, allows the Chord network overlay layer to function independently of application-layer concerns such as replication.

The demo module is a single server demo application that can be used to experiment with Chord's network overlay concepts. It provides an RESTful interface for creating nodes, and a browser-based frontend for visualising a Chord ring.

To start the demo server using SBT:

sbt "demo/runMain com.tristanpenman.chordial.demo.Demo"

Once the server has started, the browser-based interface should be accessible via http://127.0.0.1:4567/eventstream/websocket.html. This page opens a WebSocket connection to the server, and will be updated with nodes and lines representing their successor relationships as they are added to the network.

Nodes can be created via POST requests to the http://127.0.0.1:4567/nodes endpoint. A new node could be created using cURL:

curl -XPOST -w"\n" http://127.0.0.1:4567/nodes

This would create a new node (and a new Chord network). The response will contain a JSON representation of the new node:

{"nodeId":6,"successorId":6,"active":true}

Although this demo allows you to create multiple independent Chord networks, you will generally want to create nodes that join an existing network. To create a node that is connected to an existing network, you can specify an existing node as a seed ID. For example:

curl -XPOST -w"\n" http://127.0.0.1:4567/nodes?seed_id=6

This would return a JSON representation of the new node, such as:

{"nodeId":6,"successorId":59,"active":true}

The list of all existing nodes can be retrieved via a GET request:

curl -XGET -w"\n" http://127.0.0.1:4567/nodes

This will return a JSON array, where each element represents a node:

[{"nodeId":6,"successorId":59,"active":true}, {"nodeId":59,"successorId":6,"active":true}]

Chordial includes a basic test suite (growing all the time!), which can be run via SBT:

sbt test

This project is licensed under the Simplified BSD License. See the LICENSE file for more information.