mar/lib/server.js

MAR - Message & Reply, is a RPC library based on message exchange.

var net = require('net');

var Server = module.exports = function() {
  this._remoteMethods = {};

  this._authRequired = false;

  var that = this;
  this._socket = net.createServer(function(s) {
    new ServerClient(that, s);
  });
  this._socket.listen.apply(this._socket, arguments);
};

Server.prototype.on = function(subject, fn) {
  if (subject == 'mar.auth') this._authRequired = true;

  this._remoteMethods[subject] = fn;
};

Server.prototype._process = function(msg) {
  if (!this._remoteMethods[msg.subject]) {
    if (msg.reply) msg.reply('unsupported subject [' + msg.subject + ']');
    return;
  }

  this._remoteMethods[msg.subject](msg);
};


var ServerClient = function(server, socket) {
  this._server = server;
  this._socket = socket;

  this.authenticated = false;
  this._buffer = '';

  var that = this;

  socket.setEncoding('utf8');
  socket.setNoDelay(true);

  socket.on('data', function(data) {
    var tokens = that._tokenizer(data);
    for (var i = 0, len = tokens.length; i < len; i++) {
      that._process(tokens[i]);
    }
  });
};

ServerClient.prototype._process = function(msg) {
  try {
    msg = JSON.parse(msg);
    msg = this.prepare(msg);
    msg = this.auth(msg);
    if (msg) this._server._process(msg);
  } catch (e) {
    console.log('error', e);
  }
};

ServerClient.prototype.auth = function(msg) {
  if (!this._server._authRequired) return msg;
  if (!this.authenticated && msg.subject != 'mar.auth') {
    msg.reply('auth required');
    return;
  }

  var that = this;

  var original = msg.reply;
  msg.reply = function(err, data) {
    if (!err) that.authenticated = true;
    original(err, data);
  }
  return msg;
};

ServerClient.prototype.prepare = function(msg) {
  var that = this;

  if (msg.reply) msg.reply = function(err, data) {
    var reply = {
      id: msg.id
    }
    if (err) {
      reply.err = err;
      that._socket.write(JSON.stringify(reply) + '\0');
      return;
    }
    reply.data = data;
    that._socket.write(JSON.stringify(reply) + '\0');
  }
  return msg;
};

ServerClient.prototype._tokenizer = function(data) {
  this._buffer += data;

  var result = this._buffer.split('\0');
  if (result.length == 1) return [];

  var last = result.pop();
  if (last === '') {
    this._buffer = '';
    return result;
  } else {
    this._buffer = last;
    return result;
  }
};