client-one.js

/*
The MIT License (MIT)

Copyright (c) 2016 saikath

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

/***** this is a publisher client for tesing ****/

/** loading mqtt */

var mqtt = require("mqtt");

/*###############*/

/*** connect to the server *****/

var client = mqtt.connect('mqtt://localhost:1883');

/*##########################*/

/*** client on connect ***/
client.on("connect", function() {
  console.log("cleint is connected");
})

/*** client on reconnect ***/
client.on("reconnect", function() {
  console.log("cleint is reconnected");
})

/*** client on error ***/
client.on("error", function(err) {
  console.log("error from client --> ", err);
})

/*** client on close ***/
client.on("close", function() {
    console.log("cleint is closed");
  })
  /*** client on offline ***/
client.on("offline", function(err) {
  console.log("client is offline");
});

/** subscribe to a topic */
/*
  subscribe method takes two arguments {topic,options}.
 */
client.subscribe('topic/client', { qos: 1 }, function(err, granted) {
  if (err)
    console.log(err);
  else
    console.log("client connected : ", granted);
});

/*#####################*/

/*** publish a message ***/

//set retain true to deliver a message (like welcome messages) to the newly subscribed client.
//set qos = 1 to guarantee delivery service implement. 
//broker will always store the last retain message per topic if retain is true for messages.
client.publish('topic/client', JSON.stringify({ name: "saikat", title: "hajra" }), { retain: true, qos: 1 });

/*######################*/

/**** listen for a message ******/


client.on('message', function(topic, message) {
  console.log(message.toString()); // message is Buffer
  //console.log(message);
});

/*##########################*/