Package org.jgroups.protocols

Class RELAY

java.lang.Object
org.jgroups.stack.Protocol
org.jgroups.protocols.RELAY
public class RELAY extends Protocol
Simple relaying protocol: RELAY is added to the top of the stack, creates a channel to a bridge cluster, and - if coordinator - relays all multicast messages via the bridge cluster to the remote cluster.

This is not a big virtual cluster, e.g. consisting of {A,B,C,X,Y,Z}, but 2 autonomous clusters {A,B,C} and {X,Y,Z}, bridged together by RELAY. For example, when B multicasts a message M, A (if it happens to be the coord) relays M to X (which happens to be the other cluster's coordinator). X then re-broadcasts M, with M.src being a ProxyUUID(X,B). This means that the sender of M in the {X,Y,Z} cluster will be X for all practical purposes, but the original sender B is also recorded, for sending back a response.

See [1] and [2] for details.

[1] https://jira.jboss.org/browse/JGRP-747

[2] doc/design/RELAY.txt

Since:
2.12
Author:
Bela Ban

  • Field Details

    • site

      protected String site

    • bridge_props

      protected String bridge_props

    • bridge_name

      protected String bridge_name

    • relay

      protected boolean relay

    • present_global_views

      protected boolean present_global_views

    • local_addr

      protected Address local_addr

    • is_coord

      protected volatile boolean is_coord

    • coord

      protected volatile Address coord

    • bridge

      protected JChannel bridge
      The bridge between the two local clusters, usually based on a TCP config

    • local_view

      protected View local_view
      The view of the local cluster

    • bridge_view

      protected View bridge_view
      The view of the bridge cluster, usually consists of max 2 nodes

    • remote_view

      protected View remote_view
      The view of the remote cluster

    • global_view

      protected View global_view
      The combined view of local and remote cluster

    • global_view_id

      protected long global_view_id
      To generate new global views

    • timer

      protected TimeScheduler timer

    • remote_view_fetcher_future

      protected Future<?> remote_view_fetcher_future

  • Constructor Details

    • RELAY

      public RELAY()

  • Method Details

    • setRelay

      public void setRelay(boolean relay)

    • getLocalView

      public String getLocalView()

    • getBridgeView

      public String getBridgeView()

    • getRemoteView

      public String getRemoteView()

    • getGlobalView

      public String getGlobalView()

    • 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

    • 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

    • 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

    • 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

    • handleView

      protected void handleView(View view)

    • installView

      protected Object installView(byte[] buf, int offset, int length)

    • forward

      protected void forward(byte[] buffer, int offset, int length)
      Forwards the message across the TCP link to the other local cluster

    • forwardToCoord

      protected void forwardToCoord(Message msg)
      Wraps the message annd sends it to the current coordinator

    • sendViewToRemote

      protected void sendViewToRemote(RELAY.ViewData view_data, boolean use_seperate_thread)

    • generateGlobalView

      protected View generateGlobalView(View local_view, View remote_view)

    • generateGlobalView

      protected View generateGlobalView(View local_view, View remote_view, boolean merge)

    • createBridge

      protected void createBridge()

    • sendOnLocalCluster

      protected void sendOnLocalCluster(byte[] buf, int offset, int length)

    • sendViewOnLocalCluster

      protected void sendViewOnLocalCluster(Address dest, View remote_view, View global_view, boolean use_seperate_thread)

    • sendViewOnLocalCluster

      protected void sendViewOnLocalCluster(Address dest, RELAY.ViewData data, boolean use_seperate_thread)

    • isLocal

      protected boolean isLocal(Address dest)
      Does the payload match the 'site' ID. Checks only unicast destinations (multicast destinations return true)

    • startRemoteViewFetcher

      protected void startRemoteViewFetcher()

    • stopRemoteViewFetcher

      protected void stopRemoteViewFetcher()