IPC combined with EventEmitter2

First, RTFM child.send(message[, sendHandle]).

The sendHandle option to child.send() is for sending a TCP server or socket object to another process. The child will receive the object as its second argument to the message event.

This means that you won't be able to do things like:

child.send('message', {some: 'data'}, [data])

List of accepted instances. If you look a but further in the code, internal messages are sent with the first argument. As stated in the docs:

There is a special case when sending a {cmd: 'NODE_foo'} message.

Then, I thought it could be nice to do:

ipc.send('started')

var child = fork('child')
child.once('started', dosomething)

Internally I just had to combine EventEmitter and use the first argument to pass an array of arguments.

  var ipc = IPCEE(process)

  ipc.send('started')

  ipc.on('ping', function() {
    ipc.send('pong') 
  })

  var server = fork('some/node/app.js')
  var client = IPCEE(server)

  client.once('started', function() {
    client.send('ping')
  })

  client.once('*.pong', function() {
    console.log('\o/')
  })

Or with namespaces:

  var ipc = IPCEE(process, {wildcard: true})

  ipc.send('started')

  ipc.on('ping:me', function() {
    ipc.send('me:pong')
  })

  var server = fork('some/node/app.js')
  var client = IPCEE(server, {wildcard: true})

  client.once('started', function() {
    client.send('ping.*')
  })

  client.once('*.pong', function() {
    console.log('\o/') 
  })

Using the first argument of child_process.send(), Nodejs IPC will transport strings. Javascript objects are encoded with json internally. That said, You won't be able to pass instances.

Example:

process.on('uncaughtException', function(err) {
  ipc.send('error', err.toString(), err.stack)

  process.nextTick(function() {
    process.exit(1) 
  })
})

Here, Temptation would be to send the full Error object but JSON.stringify(new Error('test')) will return '{}'.

IPCEE does not override any of the internals methods. This means that you'll still be able to get messages from the standard way:

process.on('message', function(m, handle) {
  if(m === 'server') {
    //do something with handle 
  }
})

But it will handle accepted instances in an easy way too. For example, sending a Socket:

//server.js
ipc.send('socket', sock)
//child.js
ipc.on('socket', function(sock) {
  assert(sock instanceof Socket)
})

The MIT License (MIT)

Copyright (c) 2015 Antoine Bluchet

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