org.apache.directory.mitosis.service.protocol.handler
Class ReplicationClientContextHandler

java.lang.Object
  org.apache.directory.mitosis.service.protocol.handler.ReplicationClientContextHandler

All Implemented Interfaces:

ReplicationContextHandler

public class ReplicationClientContextHandler
extends java.lang.Object
implements ReplicationContextHandler

ReplicationContextHandler that implements client-side replication logic which sends any changes out-of-date to server. The following is the detailed protocol flow and the description of the replication logic execution.

• ClientConnectionManager connects the client to the server.
• The client sends LoginMessage to the server.
• The server responds with LoginAckMessage to the client
  • Unless the response code is Constants.OK, disconnect. Next connection attempt is performed by ClientConnectionManager later.
  • Otherwise, the state of the ReplicationContext changes to ReplicationContext.State.READY, and proceed.
• The client tries to transfer the data that server needs from in ReplicationStore periodically using contextIdle(ReplicationContext, IdleStatus) event, which is implemented using sessionIdle event in MINA.
  • The client sends a BeginLogEntriesMessage to the server.
  • The server responds with BeginLogEntriesAckMessage.
    • If the response code is Constants.OK,
      • BeginLogEntriesAckMessage contains a Update Vector (UV) of the server. The client compares the received UV and the client's Purge Vector (PV).
        • If the PV is greater than the UV, this means the client can't send all operation logs that server needs to get synchronized. This usually means that the server has been offline for too long time and got out-of-sync finally due to the log-purging process of the client side (see ReplicationConfiguration.getLogMaxAge()). The clients sends all entries in the DIT to the server, and the server overwrites its current DIT with the received entries.
        • Otherwise, the client sends only the changed part since the last synchronization by querying its ReplicationStore by calling ReplicationStore.getLogs(CSNVector, boolean).
        • The data transfer is very simple. It's asynchronous request-response exchange. The client sends LogEntryMessage, and then the server responds with LogEntryAckMessage.
      • If the response code is not Constants.OK, retry later.

  Version:

  $Rev: 116 $, $Date: 2006-09-18 13:47:53Z $

  Author:

  The Apache Directory Project (dev@directory.apache.org)

  Constructor Summary

  ReplicationClientContextHandler()
  

  Method Summary

  boolean	beginReplication(ReplicationContext ctx)
  void	contextBegin(ReplicationContext ctx) Invoked when a connection is established between two replicas.
  void	contextEnd(ReplicationContext ctx) Invoked when a connection is closed between two replicas.
  void	contextIdle(ReplicationContext ctx, org.apache.mina.common.IdleStatus status) Invoked when two replicas are not exchanging any data for certain amount of time.
  void	exceptionCaught(ReplicationContext ctx, java.lang.Throwable cause) Invoked when an exception is raised during the communication or executing replication logic.
  void	messageReceived(ReplicationContext ctx, java.lang.Object message) Invoked when a message is received from a peer replica.
  void	messageSent(ReplicationContext ctx, java.lang.Object message) Invoked when a message is received from a peer replica.
  org.apache.mina.common.WriteFuture	writeTimeLimitedMessage(ReplicationContext ctx, java.lang.Object message) A helper to write a message and schedule that message for expiration.

  Methods inherited from class java.lang.Object

  clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  Constructor Detail

  ReplicationClientContextHandler

  public ReplicationClientContextHandler()

  Method Detail

  contextBegin

  public void contextBegin(ReplicationContext ctx)
                    throws java.lang.Exception

  Description copied from interface: ReplicationContextHandler

  Invoked when a connection is established between two replicas.

  Specified by:

  contextBegin in interface ReplicationContextHandler

  Throws:

  java.lang.Exception

  contextEnd

  public void contextEnd(ReplicationContext ctx)
                  throws java.lang.Exception

  Description copied from interface: ReplicationContextHandler

  Invoked when a connection is closed between two replicas.

  Specified by:

  contextEnd in interface ReplicationContextHandler

  Throws:

  java.lang.Exception

  messageReceived

  public void messageReceived(ReplicationContext ctx,
                              java.lang.Object message)
                       throws java.lang.Exception

  Description copied from interface: ReplicationContextHandler

  Invoked when a message is received from a peer replica.

  Specified by:

  messageReceived in interface ReplicationContextHandler

  Throws:

  java.lang.Exception

  messageSent

  public void messageSent(ReplicationContext ctx,
                          java.lang.Object message)
                   throws java.lang.Exception

  Description copied from interface: ReplicationContextHandler

  Invoked when a message is received from a peer replica.

  Specified by:

  messageSent in interface ReplicationContextHandler

  Throws:

  java.lang.Exception

  writeTimeLimitedMessage

  public org.apache.mina.common.WriteFuture writeTimeLimitedMessage(ReplicationContext ctx,
                                                                    java.lang.Object message)

  A helper to write a message and schedule that message for expiration.

  Parameters:

  ctx - the replication context

  message - the message to replicate

  Returns:

  the write future to block on this replication message transmission

  exceptionCaught

  public void exceptionCaught(ReplicationContext ctx,
                              java.lang.Throwable cause)
                       throws java.lang.Exception

  Description copied from interface: ReplicationContextHandler

  Invoked when an exception is raised during the communication or executing replication logic.

  Specified by:

  exceptionCaught in interface ReplicationContextHandler

  Throws:

  java.lang.Exception

  contextIdle

  public void contextIdle(ReplicationContext ctx,
                          org.apache.mina.common.IdleStatus status)
                   throws java.lang.Exception

  Description copied from interface: ReplicationContextHandler

  Invoked when two replicas are not exchanging any data for certain amount of time.

  Specified by:

  contextIdle in interface ReplicationContextHandler

  Throws:

  java.lang.Exception

  beginReplication

  public boolean beginReplication(ReplicationContext ctx)