socket.io-nats

Adapter to enable broadcasting of events to multiple separate socket.io server nodes through NATS, based on the socket.io-redis

How to use

var io = require('socket.io')(3000);
var nats = require('socket.io-nats');
io.adapter(nats());

By running socket.io with the socket.io-nats 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-nats-emitter.

API

adapter(opts)

The following options are allowed:

• key: the name of the key to pub/sub events on as prefix (socket.io)
• delimiter: optional, channels delimiter
• nc: optional, the nats client
• ...: nats client options (ignored if nats client is supplied)

If you decide to supply nc, make sure you use node_nats as a client or one with an equivalent API.

NatsAdapter

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

• uid
• prefix
• nc
• delimiter

Client error handling

Access the nc property of the Nats Adapter instance to subscribe to its error event:

var nats = require('socket.io-nats');
var adapter = nats();
adapter.nats.on('error', function(){});

Custom client (eg: clustered nats)

If you need to create a NatsAdapter to a Nats client instance that has clustered connection

var nats = require('nats');
 
var servers = ['nats://nats.io:4222', 'nats://nats.io:5222', 'nats://nats.io:6222'];
 
// Randomly connect to a server in the cluster group.
var nc = nats.connect({'servers': servers});
 
// currentServer is the URL of the connected server.
console.log("Connected to " + nc.currentServer.host);
 
var adapter = require('socket.io-nats');
 
io.adapter(adapter({ nc: nc }));

Protocol

The socket.io-nats adapter broadcasts and receives messages on particularly named Nats 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
• delimiter: The delimiter of channel name. Default value is .. Changed by setting opts.delimiter in adapter(opts) constructor
• namespace: See https://github.com/socketio/socket.io#namespace.
• room : Used if targeting a specific room, the room is URL encoded.

License

MIT