Package 

Interface MqttCallback

  • 
public interface MqttCallback

    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: setCallback and setCallback

    • Method Summary

      Modifier and Type Method Description
      abstract void connectionLost(Throwable cause) This method is called when the connection to the server is lost.
      abstract boolean messageArrived(String topic, MqttMessage message) This method is called when a message arrives from the server.
      abstract void deliveryComplete(IMqttDeliveryToken token) Called when delivery for a message has been completed, and all acknowledgments have been received.
      abstract void fastReconnect()

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Method Detail

      • connectionLost

         abstract void connectionLost(Throwable cause)

        This method is called when the connection to the server is lost.

        Parameters:
        cause - the reason behind the loss of connection.

      • messageArrived

         abstract boolean messageArrived(String topic, MqttMessage message)

        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.

        Parameters:
        topic - name of the topic on the message was published to
        message - the actual message.

      • deliveryComplete

         abstract void deliveryComplete(IMqttDeliveryToken token)

        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.

        Parameters:
        token - the delivery token associated with the message.