/**
* 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");
}
/**
* Constructs an instance of the sample client wrapper
*
* @param brokerUrl the url to connect to
* @param clientId the client id to connect with
* @param cleanSession clear state at end of connection or not (durable or non-durable
* subscriptions)
* @param quietMode whether debug should be printed to standard out
* @param userName the username to connect with
* @param password the password for the user
* @throws MqttException
*/
public SampleAsyncWait(
String brokerUrl,
String clientId,
boolean cleanSession,
boolean quietMode,
String userName,
String password)
throws MqttException {
this.brokerUrl = brokerUrl;
this.quietMode = quietMode;
this.clean = cleanSession;
this.userName = userName;
this.password = password;
// This sample stores in a temporary directory... where messages temporarily
// stored until the message has been delivered to the server.
// ..a real application ought to store them somewhere
// where they are not likely to get deleted or tampered with
String tmpDir = System.getProperty("java.io.tmpdir");
MqttDefaultFilePersistence dataStore = new MqttDefaultFilePersistence(tmpDir);
try {
// Construct the connection options object that contains connection parameters
// such as cleanSession and LWT
conOpt = new MqttConnectOptions();
conOpt.setCleanSession(clean);
if (password != null) {
conOpt.setPassword(this.password.toCharArray());
}
if (userName != null) {
conOpt.setUserName(this.userName);
}
// Construct a non-blocking MQTT client instance
client = new MqttAsyncClient(this.brokerUrl, clientId, dataStore);
// Set this wrapper as the callback handler
client.setCallback(this);
} catch (MqttException e) {
e.printStackTrace();
log("Unable to set up client: " + e.toString());
System.exit(1);
}
}
public static void main(String[] args) {
clearConsolidation();
try {
final MqttAsyncClient mqttClient =
new MqttAsyncClient(BROKER_URI, MqttClient.generateClientId(), new MemoryPersistence());
mqttClient.setCallback(
new MqttCallback() {
@Override
public void messageArrived(String topic, MqttMessage message) throws Exception {
try {
// TODO retrieve sensor value and sensor name
double sensorValue = 0;
// sensorValue = ...
String sensorName = null;
// sensorName = ...
ConsolidatedValues conso = consolidation.get(sensorName);
if (conso == null) {
conso = new ConsolidatedValues();
consolidation.put(sensorName, conso);
}
conso.addSample(sensorValue);
// end of the minute?
if (System.currentTimeMillis() > nextMinuteTimestamp) {
System.out.println("PUBLISH CONSOLIDATION");
// TODO publish computed average value
clearConsolidation();
}
} catch (RuntimeException e) {
e.printStackTrace();
}
}
@Override
public void deliveryComplete(IMqttDeliveryToken token) {
// not used
}
@Override
public void connectionLost(Throwable cause) {
System.out.println("Connection lost: " + cause.getLocalizedMessage());
}
});
mqttClient.connect(
null,
new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
// TODO subscribe to live data
}
@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
exception.printStackTrace();
}
});
} catch (MqttException e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws JSONException, MqttException {
final MqttAsyncClient mqtt = MqttAsyncClient.createMqttClient("52fcc04c4dc903d66d6f8f92");
// System.out.println(getCid());
}
/**
* 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");
}