var client = mqtt.connect('ws://host:port', {
    username: 'username',
    clientId: 'client-id',
    password: 'password'
});

client.subscribe('endpoint');

client.on('message', function (topic, payload) {
    var evt = topic.toString(), args = payload.toString();
    return _isJsonObj(args) && $rootScope.$broadcast(evt, JSON.parse(args));
});