Class MessageListenerAdapter

java.lang.Object
org.jgroups.blocks.MessageListenerAdapter
All Implemented Interfaces:
ExtendedMessageListener, MessageListener
public class MessageListenerAdapter extends Object implements ExtendedMessageListener
This class provides multiplexing possibilities for MessageListener instances. Usually, we have more than one instance willing to listen to incoming messages, but only one that can produce state for group. PullPushAdapter allows only one instance of MessageListener to be registered for message notification. With help of this class you can overcome this limitation.
Author:
Roman Rokytskyy (rrokytskyy@acm.org)

  • Field Details

    • stateListener

      protected MessageListener stateListener

    • messageListeners

      protected final HashSet messageListeners

    • messageListenersCache

      protected MessageListener[] messageListenersCache

  • Constructor Details

    • MessageListenerAdapter

      public MessageListenerAdapter()
      Create default instance of this class. Newly created instance will have no message or state listeners. You have to use addMessageListener(MessageListener) or removeMessageListener(MessageListener) to add or remove message listeners, and setStateListener(MessageListener) to set listener that will participate in state transfer.

    • MessageListenerAdapter

      public MessageListenerAdapter(MessageListener mainListener)
      Create instance of this class. mainListener is a main listener instance that received message notifications and can get and set group state.
      Parameters:
      mainListener - instance of MessageListener that will provide state messages.

  • Method Details

    • getState

      public byte[] getState()
      Get state from state listener if present.
      Specified by:
      getState in interface MessageListener
      Returns:
      current state of the group state or null if no state listeners were registered.

    • getState

      public byte[] getState(String state_id)
      Description copied from interface: ExtendedMessageListener
      Allows an application to provide a partial state as a byte array
      Specified by:
      getState in interface ExtendedMessageListener
      Parameters:
      state_id - id of the partial state requested
      Returns:
      partial state for the given state_id

    • getState

      public void getState(OutputStream ostream)
      Description copied from interface: ExtendedMessageListener
      Allows an application to write a state through a provided OutputStream. An application is obligated to always close the given OutputStream reference.
      Specified by:
      getState in interface ExtendedMessageListener
      Parameters:
      ostream - the OutputStream
      See Also:

    • getState

      public void getState(String state_id, OutputStream ostream)
      Description copied from interface: ExtendedMessageListener
      Allows an application to write a partial state through a provided OutputStream. An application is obligated to always close the given OutputStream reference.
      Specified by:
      getState in interface ExtendedMessageListener
      Parameters:
      state_id - id of the partial state requested
      ostream - the OutputStream
      See Also:

    • receive

      public void receive(Message msg)
      Receive message from group. This method will send this message to each message listener that was registered in this adapter.
      Specified by:
      receive in interface MessageListener
      Parameters:
      msg - message to distribute within message listeners.

    • setState

      public void setState(byte[] state)
      Set state of ths group. This method will delegate call to state listener if it was previously registered.
      Specified by:
      setState in interface MessageListener
      Parameters:
      state -

    • setState

      public void setState(String state_id, byte[] state)
      Description copied from interface: ExtendedMessageListener
      Allows an application to read a partial state indicated by state_id from a given state byte array parameter.
      Specified by:
      setState in interface ExtendedMessageListener
      Parameters:
      state_id - id of the partial state requested
      state - partial state for the given state_id

    • setState

      public void setState(InputStream istream)
      Description copied from interface: ExtendedMessageListener
      Allows an application to read a state through a provided InputStream. An application is obligated to always close the given InputStream reference.
      Specified by:
      setState in interface ExtendedMessageListener
      Parameters:
      istream - the InputStream
      See Also:

    • setState

      public void setState(String state_id, InputStream istream)
      Description copied from interface: ExtendedMessageListener
      Allows an application to read a partial state through a provided InputStream. An application is obligated to always close the given InputStream reference.
      Specified by:
      setState in interface ExtendedMessageListener
      Parameters:
      state_id - id of the partial state requested
      istream - the InputStream
      See Also:

    • addMessageListener

      public final void addMessageListener(MessageListener listener)
      Add message listener to this adapter. This method registers listener for message notification.

      Note, state notification will not be used.

    • removeMessageListener

      public void removeMessageListener(MessageListener listener)
      Remove message listener from this adapter. This method deregisters listener from message notification.

    • setStateListener

      public void setStateListener(MessageListener listener)
      Register listener for state notification events. There can be only one state listener per adapter.