Class STATE_TRANSFER

java.lang.Object
org.jgroups.stack.Protocol
org.jgroups.protocols.pbcast.STATE_TRANSFER
public class STATE_TRANSFER extends Protocol
New STATE_TRANSFER protocol based on PBCAST. Compared to the one in ./protocols, it doesn't need a QUEUE layer above it. A state request is sent to a chosen member (coordinator if null). That member makes a copy D of its current digest and asks the application for a copy of its current state S. Then the member returns both S and D to the requester. The requester first sets its digest to D and then returns the state to the application.
Version:
$Id: STATE_TRANSFER.java,v 1.76.2.1 2008/02/13 02:13:24 vlada Exp $
Author:
Bela Ban

  • Constructor Details

    • STATE_TRANSFER

      public STATE_TRANSFER()

  • Method Details

    • getName

      public String getName()
      All protocol names have to be unique !
      Specified by:
      getName in class Protocol

    • getNumberOfStateRequests

      public int getNumberOfStateRequests()

    • getNumberOfStateBytesSent

      public long getNumberOfStateBytesSent()

    • getAverageStateSize

      public double getAverageStateSize()

    • requiredDownServices

      public Vector<Integer> requiredDownServices()
      Description copied from class: Protocol
      List of events that are required to be answered by some layer below.
      Overrides:
      requiredDownServices in class Protocol
      Returns:
      Vector (of Integers)

    • resetStats

      public void resetStats()
      Overrides:
      resetStats in class Protocol

    • setProperties

      public boolean setProperties(Properties props)
      Description copied from class: Protocol
      Configures the protocol initially. A configuration string consists of name=value items, separated by a ';' (semicolon), e.g.:
      "loopback=false;unicast_inport=4444"
      Overrides:
      setProperties in class Protocol

    • init

      public void init() throws Exception
      Description copied from class: Protocol
      Called after instance has been created (null constructor) and before protocol is started. Properties are already set. Other protocols are not yet connected and events cannot yet be sent.
      Overrides:
      init in class Protocol
      Throws:
      Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the channel constructor will throw an exception

    • start

      public void start() throws Exception
      Description copied from class: Protocol
      This method is called on a Channel.connect(String). Starts work. Protocols are connected and queues are ready to receive events. Will be called from bottom to top. This call will replace the START and START_OK events.
      Overrides:
      start in class Protocol
      Throws:
      Exception - Thrown if protocol cannot be started successfully. This will cause the ProtocolStack to fail, so Channel.connect(String) will throw an exception

    • stop

      public void stop()
      Description copied from class: Protocol
      This method is called on a Channel.disconnect(). Stops work (e.g. by closing multicast socket). Will be called from top to bottom. This means that at the time of the method invocation the neighbor protocol below is still working. This method will replace the STOP, STOP_OK, CLEANUP and CLEANUP_OK events. The ProtocolStack guarantees that when this method is called all messages in the down queue will have been flushed
      Overrides:
      stop in class Protocol

    • up

      public Object up(Event evt)
      Description copied from class: Protocol
      An event was received from the layer below. Usually the current layer will want to examine the event type and - depending on its type - perform some computation (e.g. removing headers from a MSG event type, or updating the internal membership list when receiving a VIEW_CHANGE event). Finally the event is either a) discarded, or b) an event is sent down the stack using down_prot.down() or c) the event (or another event) is sent up the stack using up_prot.up().
      Overrides:
      up in class Protocol

    • down

      public Object down(Event evt)
      Description copied from class: Protocol
      An event is to be sent down the stack. The layer may want to examine its type and perform some action on it, depending on the event's type. If the event is a message MSG, then the layer may need to add a header to it (or do nothing at all) before sending it down the stack using down_prot.down(). In case of a GET_ADDRESS event (which tries to retrieve the stack's address from one of the bottom layers), the layer may need to send a new response event back up the stack using up_prot.up().
      Overrides:
      down in class Protocol