Simple MQTT Server. Tessel acts as an MQTT client sending temperature data to a host

listening-client.js

var mqtt = require('mqtt')
  // Make sure to change this to the IP address of your MQTT server
  , host = '192.168.128.204' // or localhost
  client = mqtt.createClient(1883, host, {keepalive: 10000});

// Subscribe to the temperature topic
client.subscribe('temperature');

// When a temperature is published, it will show up here
client.on('message', function (topic, message) {
  console.log("Got a message!", topic, message);
});

mqtt-server.js

// Pulled directly from the MQTT example folder
// https://github.com/adamvr/MQTT.js/blob/master/examples/server/broadcast.js
var mqtt = require('mqtt')
  , util = require('util');

mqtt.createServer(function(client) {
  var self = this;

  if (!self.clients) self.clients = {};


  client.on('connect', function(packet) {
    self.clients[packet.clientId] = client;
    client.id = packet.clientId;
    console.log('client connected!', client.id);
    client.subscriptions = [];
    client.connack({returnCode: 0});
  });

  client.on('subscribe', function(packet) {
    var granted = [];

    for (var i = 0; i < packet.subscriptions.length; i++) {
      var qos = packet.subscriptions[i].qos
        , topic = packet.subscriptions[i].topic
        , reg = new RegExp(topic.replace('+', '[^\/]+').replace('#', '.+') + '$');

      granted.push(qos);
      client.subscriptions.push(reg);
    }

    client.suback({messageId: packet.messageId, granted: granted});
  });

  client.on('publish', function(packet) {
    for (var k in self.clients) {
      var c = self.clients[k];

      for (var i = 0; i < c.subscriptions.length; i++) {
        var s = c.subscriptions[i];

        if (s.test(packet.topic)) {
          c.publish({topic: packet.topic, payload: packet.payload});
          break;
        }
      }
    }
  });

  client.on('pingreq', function(packet) {
    client.pingresp();
  });

  client.on('disconnect', function(packet) {
    client.stream.end();
  });

  client.on('close', function(packet) {
    delete self.clients[client.id];
  });

  client.on('error', function(e) {
    client.stream.end();
    console.log(e);
  });
}).listen(process.argv[2] || 1883);

console.log('listening for clients!');

mqtt-temperature-client.js

var mqtt = require('mqtt')
  // Make sure to replace this line with the IP Address of your MQTT server
  , host = '192.168.128.204'
  , port = 1883
  , client = mqtt.createClient(port, host, {keepalive: 10000})
  , tessel = require('tessel')
  , climate = require('climate-si7020').use(tessel.port['A']);

climate.on('ready', function ready() {
  console.log('climate ready');
  // We will set an interval of 5 seconds to make sure we don't use up all of Tessel's 4 sockets
  setInterval(function() {
    // Read the temperature
    climate.readTemperature(function(err, temperature) {
      // If there was no error
      if (!err) {
        console.log('publishing temp', temperature);
        // Publish the string representation of the temperature
        client.publish('temperature', temperature.toString());
      }
    });
  }, 5000);
});