/**
* Publish / send a message to an MQTT server
*
* @param topicName the name of the topic to publish to
* @param qos the quality of service to delivery the message at (0,1,2)
* @param payload the set of bytes to send to the MQTT server
* @throws MqttException
*/
public void publish(String topicName, int qos, byte[] payload) throws MqttException {
// Connect to the MQTT server
// issue a non-blocking connect and then use the token to wait until the
// connect completes. An exception is thrown if connect fails.
log("Connecting to " + brokerUrl + " with client ID " + client.getClientId());
IMqttToken conToken = client.connect(conOpt, null, null);
conToken.waitForCompletion();
log("Connected");
String time = new Timestamp(System.currentTimeMillis()).toString();
log("Publishing at: " + time + " to topic \"" + topicName + "\" qos " + qos);
// Construct the message to send
MqttMessage message = new MqttMessage(payload);
message.setQos(qos);
// Send the message to the server, control is returned as soon
// as the MQTT client has accepted to deliver the message.
// Use the delivery token to wait until the message has been
// delivered
IMqttDeliveryToken pubToken = client.publish(topicName, message, null, null);
pubToken.waitForCompletion();
log("Published");
// Disconnect the client
// Issue the disconnect and then use a token to wait until
// the disconnect completes.
log("Disconnecting");
IMqttToken discToken = client.disconnect(null, null);
discToken.waitForCompletion();
log("Disconnected");
}
/**
* Subscribe to a topic on an MQTT server Once subscribed this method waits for the messages to
* arrive from the server that match the subscription. It continues listening for messages until
* the enter key is pressed.
*
* @param topicName to subscribe to (can be wild carded)
* @param qos the maximum quality of service to receive messages at for this subscription
* @throws MqttException
*/
public void subscribe(String topicName, int qos) throws MqttException {
// Connect to the MQTT server
// issue a non-blocking connect and then use the token to wait until the
// connect completes. An exception is thrown if connect fails.
log("Connecting to " + brokerUrl + " with client ID " + client.getClientId());
IMqttToken conToken = client.connect(conOpt, null, null);
conToken.waitForCompletion();
log("Connected");
// Subscribe to the requested topic.
// Control is returned as soon client has accepted to deliver the subscription.
// Use a token to wait until the subscription is in place.
log("Subscribing to topic \"" + topicName + "\" qos " + qos);
IMqttToken subToken = client.subscribe(topicName, qos, null, null);
subToken.waitForCompletion();
log("Subscribed to topic \"" + topicName);
// Continue waiting for messages until the Enter is pressed
log("Press <Enter> to exit");
try {
System.in.read();
} catch (IOException e) {
// If we can't read we'll just exit
}
// Disconnect the client
// Issue the disconnect and then use the token to wait until
// the disconnect completes.
log("Disconnecting");
IMqttToken discToken = client.disconnect(null, null);
discToken.waitForCompletion();
log("Disconnected");
}