teasealancs/socket.io-redis

Adapter to enable broadcasting of events to multiple separate socket.io server nodes.

socket.io-redis

How to use

var io = require('socket.io')(3000);
var redis = require('socket.io-redis');
io.adapter(redis({ host: 'localhost', port: 6379 }));

By running socket.io with the socket.io-redis adapter you can run multiple socket.io instances in different processes or servers that can all broadcast and emit events to and from each other.

If you need to emit events to socket.io instances from a non-socket.io process, you should use socket.io-emitter.

API

adapter(uri[, opts])

uri is a string like localhost:6379 where your redis server is located. For a list of options see below.

adapter(opts)

The following options are allowed:

• key: the name of the key to pub/sub events on as prefix (socket.io)
• host: host to connect to redis on (localhost)
• port: port to connect to redis on (6379)
• subEvent: optional, the redis client event name to subscribe to (messageBuffer)
• pubClient: optional, the redis client to publish events on
• subClient: optional, the redis client to subscribe to events on
• requestsTimeout: optional, after this timeout the adapter will stop waiting from responses to request (1000ms)
• withChannelMultiplexing: optional, whether channel multiplexing is enabled (a new subscription will be trigggered for each room) (true)

If you decide to supply pubClient and subClient, make sure you use node_redis as a client or one with an equivalent API.

RedisAdapter

The redis adapter instances expose the following properties that a regular Adapter does not

• uid
• prefix
• pubClient
• subClient
• requestsTimeout

RedisAdapter#clients(rooms:Array, fn:Function)

Returns the list of client IDs connected to rooms across all nodes. See Namespace#clients(fn:Function)

RedisAdapter#clientRooms(id:String, fn:Function)

Returns the list of rooms the client with the given ID has joined (even on another node).

Client error handling

Access the pubClient and subClient properties of the Redis Adapter instance to subscribe to its error event:

var redis = require('socket.io-redis');
var adapter = redis('localhost:6379');
adapter.pubClient.on('error', function(){});
adapter.subClient.on('error', function(){});

The errors emitted from pubClient and subClient will also be forwarded to the adapter instance:

var io = require('socket.io')(3000);
var redis = require('socket.io-redis');
io.adapter(redis({ host: 'localhost', port: 6379 }));
io.of('/').adapter.on('error', function(){});

Custom client (eg: with authentication)

If you need to create a redisAdapter to a redis instance that has a password, use pub/sub options instead of passing a connection string.

var redis = require('redis').createClient;
var adapter = require('socket.io-redis');
var pub = redis(port, host, { auth_pass: "pwd" });
var sub = redis(port, host, { auth_pass: "pwd" });
io.adapter(adapter({ pubClient: pub, subClient: sub }));

Protocol

The socket.io-redis adapter broadcasts and receives messages on particularly named Redis channels. For global broadcasts the channel name is:

prefix + '#' + namespace + '#'

In broadcasting to a single room the channel name is:

prefix + '#' + namespace + '#' + room + '#'

• prefix: The base channel name. Default value is socket.io. Changed by setting opts.key in adapter(opts) constructor
• namespace: See https://github.com/socketio/socket.io#namespace.
• room : Used if targeting a specific room.

A number of other libraries adopt this protocol including:

• socket.io-emitter
• socket.io-python-emitter

License

MIT