c3io

c3io exploits stdin and stdout for inter-process communication in order to communicate with other processes.

If you only want to communicate with parent to child in nodejs you simply can use standard child_process communication.

WORK IN PROGRESS - NOT STABLE

Use cases

Have a look at c3docker using c3io as means of communicating with docker container.

Basic usage

var c3io  = require('c3io')(options),
    spawn = require('child_process').spawn

c3io.on('message', function(msg) {
  // input request
  if ( msg.stdin ) {
    // send message [string]
    this.stdin = 'Hello World'
  }
  // stderr stream
  else if ( msg.stderr ) {
    console.log('stderr', msg.toString('utf8'))
  }
  // stdout stream
  else {
    console.log('stdout', msg.toString('utf8'))
  }
})

var child = spawn(
    'casperjs',
    ['test.js'])

c3io.pipe(child)

First a new c3io instance is created, which is basically an EventEmitter. Then you can listen to message as you would with child processes. Your child process can invoke this with simple commands. Here e.g. for casperjs.

var system = require('system'),
    casper = require("casper").create();

system.stdout.write('Hello, system.stdout.write!\n');

system.stdout.writeLine("c3io!req");
var line = system.stdin.readLine();
system.stdout.writeLine(line);

casper.echo('c3io!stp');
casper.exit();

notice [ default ] for c3io is each line a command to be passed on. For that make sure it ends with an EOL. You can change this behavior with options.protocol.

As you maybe noticed there is also the ability to push for certain commands. First there is the initial c3io! telling c3io to look for the given command. You can change the initial sequence within the environment.

env c3ctr="foo" c3len=1 node example.js

c3len configures how long the command name is. [default: 3] Currently there are following sequences. (for usage see latter example)

• c3io!req

triggers an message event in order to replay to the input request

c3io!stp is c3docker specific.

options

• protocol [ newline | native ] ~ The same format is used to send messages in both directions.
  newline
  each line is a command to be passed on. For that make sure it ends with an EOL.
  native
  each message is serialized using Buffer and is preceded with 32-bit message length in native byte order.

custom commands

It is possible to define your own commands.

var c3io = require('c3io')

c3io.options.r2d2.wrt = function(_data) {
  require('fs').writeFile('example.txt', _data)
  // skip message (no event will be emitted)
  return null
}

And executing the command in child process.

var system = require('system'),
    file_c = "Write something to File!"

// if you have line breaks within string make sure to handle them. e.g. through serializing.
system.stdout.writeLine("c3io!wrt" + file_c);

more examples

Please refer to test/main.js

Installation

npm install c3io --save

or directly from github

npm install fentas/c3io