Package org.apache.activemq.transport.mqtt.strategy

Interface MQTTSubscriptionStrategy

All Known Implementing Classes:
AbstractMQTTSubscriptionStrategy, MQTTDefaultSubscriptionStrategy, MQTTVirtualTopicSubscriptionStrategy
public interface MQTTSubscriptionStrategy
Subscription management strategy used to control how MQTT clients subscribe to destination and how messages are addressed in order to arrive on the appropriate destinations.

  • Method Summary

    Modifier and Type
    Method
    Description
    MQTTProtocolConverter
    getProtocolConverter()
     
    MQTTSubscription
    getSubscription(org.apache.activemq.command.ConsumerId consumer)
    Lookup an MQTTSubscription instance based on known ConsumerId value.
    void
    initialize(MQTTProtocolConverter protocol)
    Initialize the strategy before first use.
    boolean
    isControlTopic(org.apache.activemq.command.ActiveMQDestination destination)
    Allows the protocol handler to interrogate an destination name to determine if it is equivalent to the MQTT control topic (starts with $).
    void
    onConnect(org.fusesource.mqtt.codec.CONNECT connect)
    Allows the strategy to perform any needed actions on client connect prior to the CONNACK frame being sent back such as recovering old subscriptions and performing any clean session actions.
    void
    onReSubscribe(MQTTSubscription subscription)
    Called when a client sends a duplicate subscribe request which should force any retained messages on that topic to be replayed again as though the client had just subscribed for the first time.
    org.apache.activemq.command.ActiveMQDestination
    onSend(String topicName)
    Intercepts PUBLISH operations from the client and allows the strategy to map the target destination so that the send operation will land in the destinations that this strategy has mapped the incoming subscribe requests to.
    String
    onSend(org.apache.activemq.command.ActiveMQDestination destination)
    Intercepts send operations from the broker and allows the strategy to map the target topic name so that the client sees a valid Topic name.
    byte
    onSubscribe(String topicName, org.fusesource.mqtt.client.QoS requestedQoS)
    Called when a new Subscription is being requested.
    byte
    onSubscribe(org.fusesource.mqtt.client.Topic topic)
    Called for each Topic that a client requests to subscribe to.
    void
    onUnSubscribe(String topicName)
    Called when a client requests an un-subscribe a previous subscription.
    void
    setProtocolConverter(MQTTProtocolConverter parent)
    Sets the MQTTProtocolConverter that is the parent of this strategy object.

  • Method Details

    • initialize

      void initialize(MQTTProtocolConverter protocol) throws MQTTProtocolException
      Initialize the strategy before first use.
      Parameters:
      protocol - the MQTTProtocolConverter that is initializing the strategy
      Throws:
      MQTTProtocolException - if an error occurs during initialization.

    • onConnect

      void onConnect(org.fusesource.mqtt.codec.CONNECT connect) throws MQTTProtocolException
      Allows the strategy to perform any needed actions on client connect prior to the CONNACK frame being sent back such as recovering old subscriptions and performing any clean session actions.
      Throws:
      MQTTProtocolException - if an error occurs while processing the connect actions.

    • onSubscribe

      byte onSubscribe(org.fusesource.mqtt.client.Topic topic) throws MQTTProtocolException
      Called for each Topic that a client requests to subscribe to. The strategy needs check each Topic for duplicate subscription requests and change of QoS state.
      Parameters:
      topic - the MQTT Topic instance being subscribed to.
      Returns:
      the assigned QoS value given to the new subscription.
      Throws:
      MQTTProtocolException - if an error occurs while processing the subscribe actions.

    • onSubscribe

      byte onSubscribe(String topicName, org.fusesource.mqtt.client.QoS requestedQoS) throws MQTTProtocolException
      Called when a new Subscription is being requested. This method allows the strategy to create a specific type of subscription for the client such as mapping topic subscriptions to Queues etc.
      Parameters:
      topicName - the requested Topic name to subscribe to.
      requestedQoS - the QoS level that the client has requested for this subscription.
      Returns:
      the assigned QoS value given to the new subscription
      Throws:
      MQTTProtocolException - if an error occurs while processing the subscribe actions.

    • onReSubscribe

      void onReSubscribe(MQTTSubscription subscription) throws MQTTProtocolException
      Called when a client sends a duplicate subscribe request which should force any retained messages on that topic to be replayed again as though the client had just subscribed for the first time. The method should not unsubscribe the client as it might miss messages sent while the subscription is being recreated.
      Parameters:
      subscription - the MQTTSubscription that contains the subscription state.
      Throws:
      MQTTProtocolException

    • onUnSubscribe

      void onUnSubscribe(String topicName) throws MQTTProtocolException
      Called when a client requests an un-subscribe a previous subscription.
      Parameters:
      topicName - the name of the Topic the client wishes to unsubscribe from.
      Throws:
      MQTTProtocolException - if an error occurs during the un-subscribe processing.

    • onSend

      org.apache.activemq.command.ActiveMQDestination onSend(String topicName)
      Intercepts PUBLISH operations from the client and allows the strategy to map the target destination so that the send operation will land in the destinations that this strategy has mapped the incoming subscribe requests to.
      Parameters:
      topicName - the targeted Topic that the client sent the message to.
      Returns:
      an ActiveMQ Topic instance that lands the send in the correct destinations.

    • onSend

      String onSend(org.apache.activemq.command.ActiveMQDestination destination)
      Intercepts send operations from the broker and allows the strategy to map the target topic name so that the client sees a valid Topic name.
      Parameters:
      destination - the destination that the message was dispatched from
      Returns:
      an Topic name that is valid for the receiving client.

    • isControlTopic

      boolean isControlTopic(org.apache.activemq.command.ActiveMQDestination destination)
      Allows the protocol handler to interrogate an destination name to determine if it is equivalent to the MQTT control topic (starts with $). Since the mapped destinations that the strategy might alter the naming scheme the strategy must provide a way to reverse map and determine if the destination was originally an MQTT control topic.
      Parameters:
      destination - the destination to query.
      Returns:
      true if the destination is an MQTT control topic.

    • setProtocolConverter

      void setProtocolConverter(MQTTProtocolConverter parent)
      Sets the MQTTProtocolConverter that is the parent of this strategy object.
      Parameters:
      parent - the MQTTProtocolConverter that owns this strategy.

    • getProtocolConverter

      MQTTProtocolConverter getProtocolConverter()
      Returns:
      the MQTTProtocolConverter that owns this strategy.

    • getSubscription

      MQTTSubscription getSubscription(org.apache.activemq.command.ConsumerId consumer)
      Lookup an MQTTSubscription instance based on known ConsumerId value.
      Parameters:
      consumer - the consumer ID to lookup.
      Returns:
      the MQTTSubscription for the consumer or null if no subscription exists.