Package org.jgroups.blocks

Class NotificationBus

java.lang.Object
org.jgroups.blocks.NotificationBus
All Implemented Interfaces:
MembershipListener, MessageListener, Receiver
public class NotificationBus extends Object implements Receiver
This class provides notification sending and handling capability. Producers can send notifications to all registered consumers. Provides hooks to implement shared group state, which allows an application programmer to maintain a local cache which is replicated by all instances. NotificationBus sits on top of a channel, however it creates its channel itself, so the application programmers do not have to provide their own channel.
Author:
Bela Ban

  • Field Details

    • log

      protected final org.apache.commons.logging.Log log

  • Constructor Details

  • Method Details

    • setConsumer

      public void setConsumer(NotificationBus.Consumer c)

    • getLocalAddress

      public Address getLocalAddress()

    • getMembership

      public Vector getMembership()
      Returns a reference to the real membership: don't modify. If you need to modify, make a copy first !
      Returns:
      Vector of Address objects

    • getChannel

      public Channel getChannel()
      Answers the Channel. Used to operate on the underlying channel directly, e.g. perform operations that are not provided using only NotificationBus. Should be used sparingly.
      Returns:
      underlying Channel

    • isCoordinator

      public boolean isCoordinator()

    • start

      public void start() throws Exception
      Throws:
      Exception

    • stop

      public void stop()

    • sendNotification

      public void sendNotification(Serializable n)
      Pack the argument in a Info, serialize that one into the message buffer and send the message

    • sendNotification

      public void sendNotification(Address dest, Serializable n)
      Pack the argument in a Info, serialize that one into the message buffer and send the message

    • getCacheFromCoordinator

      public Serializable getCacheFromCoordinator(long timeout, int max_tries)
      Determines the coordinator and asks it for its cache. If there is no coordinator (because we are first member), null will be returned. Used only internally by NotificationBus.
      Parameters:
      timeout - Max number of msecs until the call returns
      max_tries - Max number of attempts to fetch the cache from the coordinator

    • getCacheFromMember

      public Serializable getCacheFromMember(Address mbr, long timeout, int max_tries)
      Determines the coordinator and asks it for its cache. If there is no coordinator (because we are first member), null will be returned. Used only internally by NotificationBus.
      Parameters:
      mbr - The address of the member from which to fetch the state. If null, the current coordinator will be asked for the state
      timeout - Max number of msecs until the call returns - if timeout elapses null will be returned
      max_tries - Max number of attempts to fetch the cache from the coordinator (will be set to 1 if invalid input: '<' 1)

    • notifyConsumer

      public void notifyConsumer(Serializable n)
      Don't multicast this to all members, just apply it to local consumers.

    • receive

      public void receive(Message msg)
      Description copied from interface: MessageListener
      Called when a message is received.
      Specified by:
      receive in interface MessageListener
      Parameters:
      msg -

    • getState

      public byte[] getState()
      Description copied from interface: MessageListener
      Answers the group state; e.g., when joining.
      Specified by:
      getState in interface MessageListener
      Returns:
      byte[]

    • setState

      public void setState(byte[] state)
      Description copied from interface: MessageListener
      Sets the group state; e.g., when joining.
      Specified by:
      setState in interface MessageListener
      Parameters:
      state -

    • viewAccepted

      public void viewAccepted(View new_view)
      Description copied from interface: MembershipListener
      Called when a change in membership has occurred. No long running actions or sending of messages should be done in this callback. If some long running action needs to be performed, it should be done in a separate thread.

      Note that on reception of the first view (a new member just joined), the channel will not yet be in the connected state. This only happens when Channel.connect(String) returns.

      Specified by:
      viewAccepted in interface MembershipListener

    • suspect

      public void suspect(Address suspected_mbr)
      Description copied from interface: MembershipListener
      Called whenever a member is suspected of having crashed, but has not yet been excluded.
      Specified by:
      suspect in interface MembershipListener

    • block

      public void block()
      Description copied from interface: MembershipListener
      Called (usually by the FLUSH protocol), as an indication that the member should stop sending messages. Any messages sent after returning from this callback might get blocked by the FLUSH protocol. When the FLUSH protocol is done, and messages can be sent again, the FLUSH protocol will simply unblock all pending messages. If a callback for unblocking is desired, implement ExtendedMembershipListener.unblock(). Note that block() is the equivalent of reception of a BlockEvent in the pull mode.
      Specified by:
      block in interface MembershipListener

    • getCache

      public Serializable getCache()