Building Arduino Projects for the Internet of Things

CHAPTER 3 ■ COMMUNICATION PROTOCOLS

//Connect MQTT Broker
Serial.println("[INFO] Connecting to MQTT Broker");
if (pubSubClient.connect( "arduinoClient" ))
{
Serial.println("[INFO] Connection to MQTT Broker Successful");

pubSubClient.subscribe(topic);
Serial.println("[INFO] Successfully Subscribed to MQTT Topic ");

Serial.println("[INFO] Publishing to MQTT Broker");
pubSubClient.publish(topic, "Test Message");
}
else
{
Serial.println("[INFO] Connection to MQTT Broker Failed");
}
}

void loop()
{
// Wait for messages from MQTT broker
pubSubClient.loop();
}

Your Arduino code is complete.

Final Product

To test the application, verify and upload the code as discussed in Chapter 1. Once the
code has been deployed, open the Serial Monitor window. You will start seeing log
messages from Arduino as shown in Figure  3-7.

Figure 3-7. MQTT: Publish/subscribe log messages