org.eclipse.paho.client.mqttv3.MqttCallback Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2009, 2014 IBM Corp.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Eclipse Distribution License v1.0 which accompany this distribution.
*
* The Eclipse Public License is available at
* http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Dave Locke - initial API and implementation and/or initial documentation
*/
package org.eclipse.paho.client.mqttv3;
/**
* Enables an application to be notified when asynchronous
* events related to the client occur.
* Classes implementing this interface
* can be registered on both types of client: {@link IMqttClient#setCallback(MqttCallback)}
* and {@link IMqttAsyncClient#setCallback(MqttCallback)}
*/
public interface MqttCallback {
/**
* This method is called when the connection to the server is lost.
*
* @param cause the reason behind the loss of connection.
*/
public void connectionLost(Throwable cause);
/**
* This method is called when a message arrives from the server.
*
*
* This method is invoked synchronously by the MQTT client. An
* acknowledgment is not sent back to the server until this
* method returns cleanly.
*
* If an implementation of this method throws an Exception, then the
* client will be shut down. When the client is next re-connected, any QoS
* 1 or 2 messages will be redelivered by the server.
*
* Any additional messages which arrive while an
* implementation of this method is running, will build up in memory, and
* will then back up on the network.
*
* If an application needs to persist data, then it
* should ensure the data is persisted prior to returning from this method, as
* after returning from this method, the message is considered to have been
* delivered, and will not be reproducible.
*
* It is possible to send a new message within an implementation of this callback
* (for example, a response to this message), but the implementation must not
* disconnect the client, as it will be impossible to send an acknowledgment for
* the message being processed, and a deadlock will occur.
*
* @param topic name of the topic on the message was published to
* @param message the actual message.
* @throws Exception if a terminal error has occurred, and the client should be
* shut down.
*/
public void messageArrived(String topic, MqttMessage message) throws Exception;
/**
* Called when delivery for a message has been completed, and all
* acknowledgments have been received. For QoS 0 messages it is
* called once the message has been handed to the network for
* delivery. For QoS 1 it is called when PUBACK is received and
* for QoS 2 when PUBCOMP is received. The token will be the same
* token as that returned when the message was published.
*
* @param token the delivery token associated with the message.
*/
public void deliveryComplete(IMqttDeliveryToken token);
}