Peergroup

A signalling server and messaging library for peer to peer communication over WebRTC data channels

To install

npm install peergroup

On the server

GroupServer = require('peergroup/server');
var server = new GroupServer({port: 3000});

In the browser

var peer = new PeerGroup('ws://localhost:3000');

peer.on('message', function(group, id, text) {
  alert(id + ' said ' + text + ' in ' + group);
});

peer.join('world').then(function() {
  peer.send('world', 'message', 'HELLO WORLD!');
});

API

• GroupServer

  • constructor(options) - creates a new GroupServer, passing the options object through to a WebSocketServer. Available options include host, port, path, and server.

  • stop() - closes the websocket server.

• PeerGroup

  • constructor({url, configuration}) - opens a connection to a group server, accepting the url to the server and optionally an RTCConfiguration object to be passed to RTCPeerConnections.

  • create(group) - attempts to create a group with the provided name. Returns a promise which will succeed after the group is created. If the group already exists the promise will be rejected. Succuessfully creating a group triggers a 'join' event with the group name.

  • join(group) - attempts to join an existing group by name, returns a promise that will be rejected if the group does not already exist. Triggers a 'join' event with the group name after successfully joining the group.

  • joinOrCreate(group) - attempts to a join a group by name, and if it does not exist, creates it. It returns a promise, and triggers a 'join' event if successful.

  • leave(group) - leaves an existing group and triggers a 'leave' event.

  • send(group, type, payload) - sends a message to every peer in a group. Type can be any string, and payload can be any JSON serializable value.

  • sendTo(group, id, type, payload) - sends a message to a specifc peer in a group.

  • peers(group) - returns a Set object containing the ids of all peers in a group.

  • on(type, callback) - adds a listener to be triggered each time a message of matching type is received or a lifecycle event occurs. Lifecycle events use symbols instead of strings as keys to avoid clashing with message types. The lifecycle events include the following:

    • open - triggered when a websocket connection to the peering server has been opened, passes the peerGroup instance as an argument.

    • close - triggered when the websocket connection to the peering server is closed

    • start - triggered when the handshake with the peering server is complete and the peerGroup instance has received an id. After this event it is safe to start creating / joining groups and sending messages.

    • join - triggered when a group is successfully joined or created, includes the groupName as an argument.

    • peer - triggered when a data channel is opened to a new peer. Includes the group and peer id as arguments.

    To listen to lifecycle events, access the symbols through the PeerGroup.events object, for example: peerGroup.on(PeerGroup.events.open, function(){});

  • off(type, callback) - removes a listener for a message type or lifecycle event.

  • close() - closes all peer connections and the websocket connection to the server. Triggers a 'close' event.

  • ready - a promise that resolves when the peerGroup instance has had an id assigned by the server and is ready to create and join rooms and send and receive message.

  • id - a unique string identifying the peer, assigned by the peering server after a connection has been established. PeerGroup stores a secret key in local storage allowing a peer to reclaim the same id every time it connects to a GroupServer.

Contributions

Contributions are welcome! Before opening a pull make sure to npm test and npm run build.

There are a lot of exciting things that can be built with peer to peer messaging in the browser - if you are interested in using this library, and have ideas or questions please don't hesitate to get in touch.