Mqtt subscribe DIO Status

The following script will send a subscribe message to the topic, if DIO status has been changed.

sdk-dio-mqtt-subscribe.are

HOST = "123.123.123.123"; 
PORT = 1883;
KEEPALIVE = 60;
PROTOCOL = "V31";
USERNAME = "mqtt-username";
PASSWORD = "mqtt-password";
CLIENT_ID = "mqtt-client-id";
TOPIC = "1/io";
QOS = 0;
RETAIN = 0; 
MESSAGE = "";
TIMEOUT = 1000;
CLEAN_SESSION = true;
MQTT_HANDLE = 0;
 
/*create new mqtt instance*/
MQTT_HANDLE = nb_mqttlib_new(CLIENT_ID, CLEAN_SESSION);
 
if (nb_mqttlib_set_protocol_version(MQTT_HANDLE, PROTOCOL)  < 0 ) {
  printf("Unable to set Protocol version\n");
    exit(1);
}
 
if (nb_mqttlib_set_user_pw(MQTT_HANDLE, USERNAME, PASSWORD) < 0 ) {
	printf("Unable to set Username and Passsword\n");
 
	exit(1);
}
 
if (nb_mqttlib_connect(MQTT_HANDLE, HOST, PORT, KEEPALIVE) < 0 ) {
	printf("Unable to connect\n");
	exit(1);
}
 
if (nb_mqttlib_subscribe(MQTT_HANDLE, TOPIC, QOS) < 0 ) {
	printf("Unable to subscribe\n");
	exit(1);
}
 
while (1) {
 
ret = nb_mqttlib_get_callback_message(MQTT_HANDLE, TIMEOUT);
 
buffer=(string) ret.msg.msg;
 
if(buffer=="1") {
	printf("switch DIO 1 on\n");
	if (nb_dio_set("out1", 1) < 0 ) {
		printf("DIO switch on failed\n");
	exit(1);
}
}else {
	if(buffer=="0") {
        printf("switch DIO 1 off\n");
        if (nb_dio_set("out1", 0) < 0 ) {
		  printf("DIO switch off failed\n");
	    exit(1);
	    }
	}
}
 
//For debugging
//dump(buffer);
 
if(ret<0){
			nb_syslog("Failed to publish mqtt message");
	}
 
//sleep(10);
}
 
exit(0);