mqtts.begin(argv[1], B9600);  // argv[1] is a serial device for XBee. ex) /dev/ttyUSB0

mqtts.init("Node-02");  // Get XBee's address64, short address and set XBee Node ID, 

mqtts.setQos(1);  // set QOS level.  0 or 1

mqtts.setWillTopic(willtopic);  // set WILLTOPIC. 

mqtts.setWillMessage(willmsg);  // set WILLMSG  those are sent automatically.

mqtts.setKeepAlive(60000);   // PINGREQ interval time

mqtts.connect();   // Before CONNECT, SEARCHGW is sent automatically, if the gateway is lost.

mqtts.subscribe(topic, callback); // Execute the callback, when the subscribed topic's data is published.

mqtts.registerTopic(topic);  // Register topic and aquire a Topic ID

mqtts.publish(topic, payload, payload_length); // publish the data, topic is converted into ID automatically.

mqtts.unsubscribe(topic);

mqtts.disconnect();

3) MQTTS.cpp

MQTT-S messages classes and some classes for client and Gateway.

4) ZBeeStack.cpp

XBee control classes base on https://code.google.com/p/xbee-arduino/ 

5) Mqtts_Defines.h

Default setting is for Arduino.  (comment out both systems)

//#define LINUX 

//#define MBED

select the system and uncoment it.

6) MqttsGateway.cpp

Gateway dummy Class for debug. Not real gateway.

7) MqttsGatewayApp.cpp

Gateway application for Debug. 

[BD] 0-7 

[D7] 1

[D6] 0 or 1

[AP] 2