socket.io-adapter-postgres

Derived from socket.io-redis.

How to use

const io = require('socket.io')(3000);
const postgres = require('socket.io-adapter-postgres');
io.adapter(postgres({ host: 'localhost', port: 5432 }));

By running socket.io with the socket.io-adapter-postgres 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:5432 where your PostgreSQL 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)
• pubClient: optional, the pg.Pool to publish events on
• subClient: optional, the pg.Client to subscribe to events on
• requestsTimeout: optional, after this timeout the adapter will stop waiting from responses to request (1000ms)

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

PostgresAdapter

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

• uid
• prefix
• pubClient
• subClient
• requestsTimeout

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

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

io.of('/').adapter.clients((err, clients) => {
  console.log(clients); // an array containing all connected socket ids
});
 
io.of('/').adapter.clients(['room1', 'room2'], (err, clients) => {
  console.log(clients); // an array containing socket ids in 'room1' and/or 'room2'
});
 
// you can also use
 
io.in('room3').clients((err, clients) => {
  console.log(clients); // an array containing socket ids in 'room3'
});

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

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

io.of('/').adapter.clientRooms('<my-id>', (err, rooms) => {
  if (err) { /* unknown id */ }
  console.log(rooms); // an array containing every room a given id has joined.
});

PostgresAdapter#allRooms(fn:Function)

Returns the list of all rooms.

io.of('/').adapter.allRooms((err, rooms) => {
  console.log(rooms); // an array containing all rooms (accross every node)
});

PostgresAdapter#remoteJoin(id:String, room:String, fn:Function)

Makes the socket with the given id join the room. The callback will be called once the socket has joined the room, or with an err argument if the socket was not found.

io.of('/').adapter.remoteJoin('<my-id>', 'room1', (err) => {
  if (err) { /* unknown id */ }
  // success
});

PostgresAdapter#remoteLeave(id:String, room:String, fn:Function)

Makes the socket with the given id leave the room. The callback will be called once the socket has left the room, or with an err argument if the socket was not found.

io.of('/').adapter.remoteLeave('<my-id>', 'room1', (err) => {
  if (err) { /* unknown id */ }
  // success
});

PostgresAdapter#remoteDisconnect(id:String, close:Boolean, fn:Function)

Makes the socket with the given id to get disconnected. If close is set to true, it also closes the underlying socket. The callback will be called once the socket was disconnected, or with an err argument if the socket was not found.

io.of('/').adapter.remoteDisconnect('<my-id>', true, (err) => {
  if (err) { /* unknown id */ }
  // success
});

PostgresAdapter#customRequest(data:Object, fn:Function)

Sends a request to every nodes, that will respond through the customHook method.

// on every node
io.of('/').adapter.customHook = (data, cb) => {
  cb('hello ' + data);
}
 
// then
io.of('/').adapter.customRequest('john', function(err, replies){
  console.log(replies); // an array ['hello john', ...] with one element per node
});

Client error handling

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

const postgres = require('socket.io-adapter-postgres');
const adapter = postgres('localhost:5432');
adapter.pubClient.on('error', function(){});
adapter.pubClient.on('connect', function(client){ client.on('error', function(){}); });
adapter.subClient.on('error', function(){});

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

const io = require('socket.io')(3000);
const 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.

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

With ioredis client

const io = require('socket.io')(3000);
const Redis = require('ioredis');
 
const cluster = new Redis.Cluster([
  {
    port: 6380,
    host: '127.0.0.1'
  },
  {
    port: 6381,
    host: '127.0.0.1'
  }
]);
 
const adapter = require('socket.io-redis');
io.adapter(adapter({ pubClient: cluster, subClient: cluster }));

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
• socket.io-emitter-go

License

MIT