dnp3/src/Master/Slave.js

A DNP 3.0 library for Node.js

let util = require('util')
let events = require('events')
let net = require('net')
let Request = require('./Request')

/*
    SLAVE CLASS
*/
let Slave = module.exports = function (options) {
  if (!(this instanceof Slave)) {
    return new Slave(options)
  }
  events.EventEmitter.call(this)

  this.master = options.master
  this.name = options.name

  // TCP options for connection
  this.host = options.host || '127.0.0.1'
  this.port = options.port && options.port >= 0 ? options.port : 20000

  // DNP options
  this.dir = options.dir && options.dir >= 0 ? options.dir : 0

  // Request pool
  this._requests = []

  // Connection socket
  this._socket = null
  // Internal state
  this._state = Slave.States.DISCONNECTED
}
util.inherits(Slave, events.EventEmitter)

Slave.States = {
  DISCONNECTED: 0,
  CONNECTING: 1,
  CONNECTED: 2
}

Slave.prototype.connect = function () {
  console.log('Slave::connect')
  if (Slave.States.DISCONNECTED === this._state) {
    console.log('Slave::connect# Connecting')
    this._state = Slave.States.CONNECTING
    var self = this
    this._socket = net.connect({
      port: this.port,
      host: this.host,
      localAddress: this.master.localAddress
    }, function () {
      console.log('Slave::_socket>connect')
      self._onConnect()
    })
  } else {
    console.log('Slave::connect# Already connected or connecting')
  }
  return this
}

Slave.prototype._onConnect = function () {
  console.log('Slave::_onConnect')
  this._state = Slave.States.CONNECTED

  this._processRequests()
}

Slave.prototype._processRequests = function () {
  console.log('Slave::_processRequests')
  if (Slave.States.CONNECTED === this._state && this._requests.length > 0) {
    var request = this._requests[0]
    console.log('Slave::_processRequests# Processing ' + request.id)
    request._send(this._onRequestReady)
  }
}

Slave.prototype._onRequestReady = function (request) {
  console.log('Slave::_onRequestReady# Request ' + request.id + ' is ready!')
  this._requests.shift()
  this._processRequests()
}

Slave.prototype.request = function (options) {
  console.log('Slave::request')
  var request

  if (Slave.States.DISCONNECTED === this._state) {
    console.log('Slave::request# Disconnected, trying to connect')
    this.connect()
  }

  options = options || {}
  options.slave = this
  this._requests.push(request = new Request(options))
  console.log('Slave::request# New request ' + request.id)

  return request
}