iot-sol/node_modules/hope-message/lib/mnode.js

Intel(r) IoT Services Orchestration Layer - HTML5 IDE + Node.js middleware to create and host distributed IoT Apps in minutes

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var _ = require("lodash");
var B = require("hope-base");
var EventEmitter = require("eventemitter3");
var BrokerClient = require("./broker_client");

var log = B.log.for_category("message/mnode");

var all_mnodes_in_this_process = {};

var MNode =
/**
 * A Message Node
 * config is optional, it may contains {
 *   id: ...,         // otherwise would automatically generate one
 *   brokers: [{      // a list of broker definitioin
 *     type: ...
 *     config: {}
 *   },  ...]
 * }
 *
 * @exports message/mnode
 */
module.exports = function MNode(config) {
  this.config = config = config || {};

  this.id = config.id || B.unique_id("MNODE_");
  this.name = config.name || "<" + config.id + ">";

  this.broker_clients = [];
  // We specially handle local broker client instead of putting it into 
  // the broker_clients array above
  this.disable_local_broker = config.disable_local_broker;
  this.local_broker_client = null;
  this.events_broker = new EventEmitter();

  B.check_warn(!_.isObject(all_mnodes_in_this_process[this.id]), 
    "message/mnode/create", "id already used in this process", this.id);

  this.events = {
    accept: {
      topics: {},
      event: new EventEmitter()
    },
    subscribe: {},
    subscribe_all: {
      topics: {},
      event: new EventEmitter()
    }
  };


  // RPC sessions
  this.rpc = {
    is_enabled: false,
    sessions: {},
    defines: {}
  };

  this.rpc_handler = this._handle_rpc_call.bind(this);


  all_mnodes_in_this_process[this.id] = this;
  MNode.event.emit("added", this);
};

MNode.event = new EventEmitter();


MNode.create$ = function(config) {
  var m = new MNode(config);
  return m.init$().then(function() {
    return m;
  });
};

MNode.dispose$ = function(mnode_id) {
  var n = all_mnodes_in_this_process[mnode_id];
  if (n) {
    delete all_mnodes_in_this_process[mnode_id];
    MNode.event.emit("removed", n);
    return n.dispose$();
  } else {
    return Promise.resolve();
  }
};


MNode.prototype.init$ = function() {
  var bc_config = this.config.brokers || [];
  if (!_.isArray(bc_config)) {
    bc_config = [bc_config];
  }
  var self = this;
  // need to keep the order of the broker_clients in config
  var todos = [];
  _.forOwn(bc_config, function(v, k) {
    todos.push(BrokerClient.create$(v.type, self, v).then(function(bc) {
      self.broker_clients[k] = bc;
    }));
  });
  todos.push(BrokerClient.create$("events", self).then(function(bc) {
    self.local_broker_client = bc;
  }));
  return Promise.all(todos);
};

MNode.prototype.dispose$ = function() {
  return Promise.all(this.broker_clients.map(function(bc) {
    return bc.dispose$();
  }));
};


MNode.prototype.updated = function() {
  MNode.event.emit("updated", this);
};


//----------------------------------------------------------------
// Helpers
//----------------------------------------------------------------

MNode.is_in_this_process = function(mnode_id) {
  return _.has(all_mnodes_in_this_process, mnode_id);
};

MNode.get_mnode_in_this_process = function(mnode_id) {
  return all_mnodes_in_this_process[mnode_id];
};

MNode.get_all_mnodes_in_this_process = function() {
  return all_mnodes_in_this_process;
};

MNode.prototype.is_in_this_process = function(mnode_id) {
  return MNode.is_in_this_process(mnode_id);
};

MNode.prototype.get_mnode_in_this_process = function(mnode_id) {
  return MNode.get_mnode_in_this_process(mnode_id);
};

MNode.prototype.validate_income_msg = function(msg, from_broker) {
  if (this.is_in_this_process(msg.from.mnode_id) && from_broker && !this.disable_local_broker) {
    if (from_broker !== this.local_broker_client) {
      return false;
    }
  }
  return true;
};


//----------------------------------------------------------------
// Message Envelop
//----------------------------------------------------------------
var _msg_seq = 1;

function _encode_send_msg(from_mnode_id, to_mnode_id, topic, msg, options) {
  return {
    type: "send",
    from: from_mnode_id,
    to: to_mnode_id,
    topic: topic,
    message: msg,
    options: options,
    seq: _msg_seq++,
    timestamp: Date.now()
  };
}

function _encode_publish_msg(from_mnode_id, topic, msg, options) {
  return {
    type: "publish",
    from: from_mnode_id,
    topic: topic,
    message: msg,
    options: options,
    seq: _msg_seq++,
    timestamp: Date.now()
  };
}



//----------------------------------------------------------------
// Accept
//----------------------------------------------------------------

/**
 * Add message handler
 * @param  {String} topic 
 * @param  {Function} cb     callback with signature cb(message, topic, from_mnode_id)
 */
MNode.prototype.accept$ = function(topic, cb) {
  log("accept", topic, "[by]", this.name);
  var has_subscribed = this.events.accept.topics[topic];
  this.events.accept.topics[topic] = true;
  this.events.accept.event.on(topic, cb);
  if (has_subscribed) {
    return Promise.resolve();
  } else {
    return Promise.all(this.broker_clients.map(function(bc) {
      return bc.accept$(topic);
    }));
  }
};

MNode.prototype.remove_accept$ = function(topic, cb) {
  log("remove_accept", "[topic]", topic, "[for]", cb ? "one cb" : "all cbs", "[by]", this.name);
  if (!this.events.accept.topics[topic]) {
    return Promise.resolve();
  }
  if (cb) {
    this.events.accept.event.removeListener(topic, cb);
  } else {
    this.events.accept.event.removeAllListeners(topic);
  }
  if (this.events.accept.event.listeners(topic, true)) {
    return Promise.resolve();
  } else {
    delete this.events.accept.topics[topic];
    return Promise.all(this.broker_clients.map(function(bc) {
      return bc.unaccept$(topic);
    }));
  }
};

MNode.prototype.clean_accepts$ = function() {
  log("clean_accepts", "[by]", this.name);
  this.events.accept.event.removeAllListeners();
  return Promise.resolve();
};


MNode.prototype.on_message_for_accept = function(msg, from_broker) {
  if (this.validate_income_msg(msg, from_broker)) {
    log("ACCEPTED", msg);
    this.events.accept.event.emit(msg.topic, msg.message, msg.topic, msg.from);
  }
};

//----------------------------------------------------------------
// Subscribe
//----------------------------------------------------------------


MNode.prototype.on_message_for_subscribe = function(msg, from_broker) {
  var e = this.events.subscribe[msg.from];
  if (e && this.validate_income_msg(msg, from_broker)) {
    log("SUBSCRIBE ARRIVED", msg);
    e.event.emit(msg.topic, msg.message, msg.topic, msg.from);
  }
};


MNode.prototype.on_message_for_subscribe_all = function(msg, from_broker) {
  if (this.validate_income_msg(msg, from_broker)) {
    log("SUBSCRIB_ALL ARRIVED", msg);
    this.events.subscribe_all.event.emit(msg.topic, msg.message, msg.topic, msg.from);
  }
};


MNode.prototype.subscribe$ = function(mnode_id, topic, cb) {
  log("subscribe", "[mnode]", mnode_id, "[topic]", topic, "[by]", this.name);
  if (!this.events.subscribe[mnode_id]) {
    this.events.subscribe[mnode_id] = {
      topics: {},
      event: new EventEmitter()
    };
  }
  var m = this.events.subscribe[mnode_id];
  var has_subscribed = m.topics[topic];
  m.topics[topic] = true;
  m.event.on(topic, cb);

  if (has_subscribed) {
    return Promise.resolve();
  } else {
    if (this.is_in_this_process(mnode_id) && !this.disable_local_broker) {
      return this.local_broker_client.subscribe$(mnode_id, topic);
    }
    return Promise.all(this.broker_clients.map(function(bc) {
      return bc.subscribe$(mnode_id, topic);
    }));
  }
};

MNode.prototype.subscribe_all$ = function(topic, cb) {
  log("subscribe_all", "[topic]", topic, "[by]", this.name);
  var has_subscribed = this.events.subscribe_all.topics[topic];
  this.events.subscribe_all.topics[topic];
  this.events.subscribe_all.event.on(topic, cb);
  if (has_subscribed) {
    return Promise.resolve();
  } 
  var todos = this.broker_clients.map(function(bc) {
      return bc.subscribe_all$(topic);
  });
  if (!this.disable_local_broker) {
    todos.push(this.local_broker_client.subscribe_all$(topic));
  }
  return Promise.all(todos);
};

MNode.prototype.unsubscribe$ = function(mnode_id, topic, cb) {
  log("unsubscribe", "[mnode]", mnode_id, "[topic]", topic,
    "[for]", cb ? "one cb" : "all cbs", "[by]", this.name);
  var m = this.events.subscribe[mnode_id];
  if (!m || !m.topics[topic]) {
    return Promise.resolve();
  }
  if (cb) {
    m.event.removeListener(topic, cb);
  } else {
    m.event.removeAllListeners(topic);
  }
  var need_unsub = false;
  if (!m.event.listeners(topic, true)) {  // no listeners now
    need_unsub = true;
    delete m.topics[topic];
    if (_.isEmpty(m.topics)) {
      delete this.events.subscribe[mnode_id];
    }
  }
  if (need_unsub) {
    if (this.is_in_this_process(mnode_id) && !this.disable_local_broker) {
      return this.local_broker_client.unsubscribe$(mnode_id, topic);
    } else {
      return Promise.all(this.broker_clients.map(function(bc) {
        return bc.unsubscribe$(mnode_id, topic);
      }));
    }
  }
};



MNode.prototype.clean_subscribe$ = function(mnode_id) {
  log("clean_subscribe", "[mnode]", mnode_id ? mnode_id : "*ALL*", "[by]", this.name);
  var self = this;
  if (mnode_id) {
    var m = this.events.subscribe[mnode_id];
    if (m) {
      return Promise.all(Object.keys(m.topics).map(function(t) {
        return self.unsubscribe$(mnode_id, t);
      }));
    }
  } else {
    return Promise.all(Object.keys(this.events.subscribe).map(function(n_id) {
      return self.clean_subscribe$(n_id);
    }));
  }
};

MNode.prototype.unsubscribe_all$ = function(topic, cb) {
  log("subscribe_all", "[topic]", topic, "[by]", this.name);
  if (!this.events.subscribe_all.topics[topic]) {
    return Promise.resolve();
  }
  if (cb) {
    this.events.subscribe_all.event.removeListener(topic, cb);
  } else {
    this.events.subscribe_all.event.removeAllListeners(topic);
  }
  if (this.events.subscribe_all.listeners(topic, true)) {
    return Promise.resolve();
  } else {
    delete this.events.subscribe_all.topics[topic];
    var todos = this.broker_clients.map(function(bc) {
      return bc.unsubscribe_all$(topic);
    });
    if (!this.disable_local_broker) {
      todos.push(this.local_broker_client.unsubscribe_all$(topic));
    }
    return Promise.all(todos);
  }
};

MNode.prototype.clean_subscribe_all$ = function() {
  log("clean_subscribe_all");
  var self = this;
  return Promise.all(Object.keys(this.events.subscribe_all.topics)
    .map(function(topic) {
      return self.unsubscribe_all$(topic);
    }));
};



//----------------------------------------------------------------
// Send
//----------------------------------------------------------------
MNode.prototype.send$ = function(mnode_id, topic, data) {
  var msg = _encode_send_msg(this.id, mnode_id, topic, data);
  if (this.is_in_this_process(mnode_id) && !this.disable_local_broker) {
    return this.local_broker_client.send$(mnode_id, topic, msg);
  } else {
    return Promise.all(this.broker_clients.map(function(bc) {
      return bc.send$(mnode_id, topic, msg);
    }));
  }
};


//----------------------------------------------------------------
// Publish
//----------------------------------------------------------------
MNode.prototype.publish$ = function(topic, data) {
  var self = this;
  var msg = _encode_publish_msg(this.id, topic, data);
  // we added additional Promise.resolve() to ensure publish$ and 
  // subscribe$ has same number of then in internal, this ensures port.sub 
  // and port.pub is executed in order, for local event impl.
  return Promise.resolve().then(function() {
    log("PUBLISH", topic, data);
    var todos = self.broker_clients.map(function(bc) {
      return bc.publish$(topic, msg);
    });
    if (!this.disable_local_broker) {
      todos.push(self.local_broker_client.publish$(topic, msg));
    }
    return Promise.all(todos);
  });
};


//----------------------------------------------------------------
// Helpers
//----------------------------------------------------------------
/**
 * Listen to events and publish them
 * @param  {Event} e      
 * @param  {Array} topics 
 */
MNode.prototype.attach_publish_to_event = function(e, topics) {
  var self = this;
  topics.forEach(function(t) {
    e.on(t, function(m) {
      self.publish$(t, m).done();
    });
  });
};

/**
 * Generate an event for subscribed messages
 * @param  {Event} e      
 * @param  {String} mnode_id
 * @param  {Array} topics 
 */
MNode.prototype.attach_event_to_subscribe$ = function(e, mnode_id, topics) {
  var self = this;
  return Promise.all(topics.map(function(t) {
    return self.subscribe$(mnode_id, t, function(msg, topic) {
      e.emit(msg, topic);
    });
  }));
};

/**
 * Generate an event for subscribe_all messages
 * @param  {Event} e      
 * @param  {Array} topics 
 */
MNode.prototype.attach_event_to_subscribe_all$ = function(e, topics) {
  var self = this;
  return Promise.all(topics.map(function(t) {
    return self.subscribe_all$(t, function(msg, topic) {
      e.emit(msg, topic);
    });
  }));
};


//----------------------------------------------------------------
// Remote Procedure Call
// 
// based on accept$ and send$
//----------------------------------------------------------------

var rpc_entry = "__HOPE__/__RPC__";

MNode.prototype._close_rpc_session = function(session_id, result, error) {
  var session = this.rpc.sessions[session_id];
  if (!session) {
    B.check_warn(false, "mnode/rpc/close_session",
      "Session expired already", session_id, result, error);
  } else {
    delete this.rpc.sessions[session_id];
    if (session.timer) {
      clearTimeout(session.timer);
    }
    if (error) {
      session.reject(_.isError(error) ? error : new Error(error));
    } else {
      session.resolve(result);
    }
  }
};

// msg {
//   session: ...,
//   type: "invoke" 
//   func: ...,
//   params: ...,
//   config: ...
// } or {
//   session: ...,
//   type: "return",
//   error / result: ...
// }
MNode.prototype._handle_rpc_call = function(msg, topic, from_mnode_id) {
  log("handle rpc", msg, from_mnode_id);
  B.check(msg.type === "invoke" || msg.type === "return",
    "mnode/rpc/handle_rpc", "Unknow msg type", msg);
  var self = this;
  if (msg.type === "invoke") {
    var f = this.rpc.defines[msg.func];
    if (!f) {
      this.send$(from_mnode_id, rpc_entry, {
        session: msg.session,
        type: "return",
        error: "RPC function " + msg.func + " not defined on " + this.id
      }).done();
    } else {
      if (_.isUndefined(msg.params)) {
        msg.params = [];
      }
      Promise.resolve(f.apply({}, msg.params)).then(function(r) {
        return self.send$(from_mnode_id, rpc_entry, {
          session: msg.session,
          type: "return",
          result: r
        });
      }).catch(function(err) {
        return self.send$(from_mnode_id, rpc_entry, {
          session: msg.session,
          type: "return",
          error: "RPC function " + msg.func + " on " + self.id + 
                  " failed due to " + err.toString()
        });
      }).done();
    }
  } else if (msg.type === "return") {
    this._close_rpc_session(msg.session, msg.result, msg.error);
  }
};


MNode.prototype.enable_rpc$ = function() {
  if (this.rpc.is_enabled) {
    return Promise.resolve();
  }
  var self = this;
  return this.accept$(rpc_entry, this.rpc_handler).then(function() {
    self.rpc.is_enabled = true;
  });
};

MNode.prototype.disable_rpc$ = function() {
  if (!this.rpc.is_enabled) {
    return Promise.resolve();
  }
  var self = this;
  return this.remove_accept$(rpc_entry, this.rpc_handler).then(function() {
    self.rpc.is_enabled = false;
  });
};


MNode.prototype.define_rpc = function(func_name, func) {
  B.check_warn(this.rpc.is_enabled, "mnode/rpc/define", 
    "RPC isn't enabled when define", func_name);
  B.check(!this.rpc.defines[func_name], "mnode/rpc/define", "Already defined:", func_name);
  B.check(_.isFunction(func), "mnode/rpc/define", "Should be a function", func);
  this.rpc.defines[func_name] = func;
};

MNode.prototype.undefine_rpc = function(func_name) {
  delete this.rpc.defines[func_name];
};


MNode.prototype.invoke_rpc$ = function(mnode_id, func_name, params, config) {
  B.check(this.rpc.is_enabled, "mnode/rpc/invoke", "RPC hasn't been enabled yet");
  var self = this;
  if (_.isUndefined(params)) {
    params = [];
  }
  if (!_.isArray(params)) {
    params = [params];
  }
  config = config || {};
  return new Promise(function(resolve, reject) {
    var session_id = B.unique_id("HOPE_RPC_SESSION_");
    var session = {
      resolve: resolve,
      reject: reject
    };
    self.rpc.sessions[session_id] = session;

    if (config.timeout > 0) {
      session.timer = setTimeout(function() {
        self._close_rpc_session(session_id, null, 
          "Timeout for invoking rpc", mnode_id, func_name, params, config);
      }, config.timeout);
    }

    self.send$(mnode_id, rpc_entry, {
      session: session_id,
      type: "invoke",
      func: func_name,
      params: params,
      config: config
    }).catch(function(err) {
      self._close_rpc_session(session_id, null, err);
    });
  });
};