public interface MqttCallback
|Modifier and Type||Method and Description|
This method is called when the connection to the server is lost.
Called when delivery for a message has been completed, and all acknowledgments have been received.
This method is called when a message arrives from the server.
void connectionLost(java.lang.Throwable cause)
cause- the reason behind the loss of connection.
void messageArrived(java.lang.String topic, MqttMessage message) throws java.lang.Exception
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.
topic- name of the topic on the message was published to
message- the actual message.
java.lang.Exception- if a terminal error has occurred, and the client should be shut down.
void deliveryComplete(IMqttDeliveryToken token)
token- the delivery token associated with the message.