emit.io

Turn a node stream into a socket.io-like 2-way messaging channel. Turn an event emitter into a stream. Multiple stream destinations and multiple listeners are supported.

example - 2 way messaging

var emitIO = require('emit.io')
var emitter = emitIO(inputStream)
var outputStream = emitIO(emitter)
socket.pipe(inputStream)
outputStream.pipe(socket)
emitter.on('remote-msg', function () {})
emitter.emit('send-to-remote', {data: 3})

Usage var emitIO = require('emit.io')

In the following section references to socket are assumed to be a duplex socket like a tcp connection or websocket connection or any other node duplex stream. You will have to add some sort of JSON encoding logic, that is left out for brevity. (JSONStream or mux-demux are recommended)

Stream->Emitter

Just pass emitIO a stream and it will return an event emitter that will listen on the stream for events

var emitter = emitIO(inStream)

Emitter->Stream

Pass emitIO an emitter and receive a stream that will channel the events. For 2-way communication, pass in the emitter that was returned by the stream->emitter call.

New Emitter

var ev = emitIO(inStream)
var outStream = emitIO(ev)
socket.pipe(inStream)
outStream.pipe(socket)

Link existing emitter into an inputStream

To hook an existing event emitter into an input and output channel do:

var ev = new EventEmitter()
var outStream = emitIO(ev)
emitIO(inStream, ev)
socket.pipe(inStream)
outStream.pipe(socket)

Hook new emitters into existing outgoing streams

You can get a new emitter from an incoming stream and hook it into an existing outgoing stream

var outStream = emitIO(someExistingEmitter)
var newEmitter = emitIO(inStream)
emitIO(newEmitter, outStream)   // now newEmitter will pipe its communication down the same channel as someExistingEmitter

Send events down multiple streams

To send events from a single emitter down multiple streams do

var MuxDemux = require('mux-demux')
var net = require('net')
var EmitFactory = require('../../.')

net.createServer(function (con) {
  var emitIO = EmitFactory()
  var mx = MuxDemux(function (stream) {
             var ev = emitIO(stream)
             var emitStream = emitIO(ev)
             emitStream.pipe(stream)

             ev.on('client-msg', function (msg) {
               console.log('server emitter', ev.eID, 'got msg', msg)
             })
             ev.emit('server-msg', 'server msg from emitter ' + ev.eID)
           })
  con.pipe(mx).pipe(con)

}).listen(8642, function () {
  var emitIO = EmitFactory()
  var con = net.connect(8642)
    , mx = MuxDemux()
  con.pipe(mx).pipe(con)
  // you can easily create a new emitter and stream for each
  // mx stream, but we are going to have more fun and wire
  // both streams into one emitter, and let that one emitter
  // send events down both streams
  var s1 = mx.createStream()
  var s2 = mx.createStream()
  var ev = emitIO(s1)
  emitIO(s2, ev) // hook s2 into our emitter
  var emitStream = emitIO(ev) // get an output stream
  emitStream.pipe(s1) // pipe output to s1
  emitStream.pipe(s2) // pipe output to s2

  ev.emit('client-msg', 'hello from the client!')

  ev.on('server-msg', function (msg) {
    console.log('client got:', msg)
  })

})

which prints

server emitter 0 got msg hello from the client!
server emitter 1 got msg hello from the client!
client got: server msg from emitter0
client got: server msg from emitter1