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

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	RELAY.Receiver
static class	RELAY.RelayHeader
protected class	RELAY.RemoteViewFetcher
protected static class	RELAY.ViewData Contains local and remote views, and UUID information

Field Summary

Fields

Modifier and Type	Field and Description
protected JChannel	bridge The bridge between the two local clusters, usually based on a TCP config
protected java.lang.String	bridge_name
protected java.lang.String	bridge_props
protected View	bridge_view The view of the bridge cluster, usually consists of max 2 nodes
protected Address	coord
protected View	global_view The combined view of local and remote cluster
protected long	global_view_id To generate new global views
protected boolean	is_coord
protected Address	local_addr
protected View	local_view The view of the local cluster
protected boolean	present_global_views
protected boolean	relay
protected View	remote_view The view of the remote cluster
protected java.util.concurrent.Future<?>	remote_view_fetcher_future
protected java.lang.String	site
protected static byte[]	SITE_ID
protected TimeScheduler	timer

Fields inherited from class org.jgroups.stack.Protocol

after_creation_hook, down_prot, ergonomics, id, log, name, stack, stats, up_prot

Constructor Summary

Constructors

Constructor and Description
RELAY()

Method Summary

Modifier and Type	Method and Description
protected void	createBridge()
java.lang.Object	down(Event evt) An event is to be sent down the stack.
protected void	forward(byte[] buffer, int offset, int length) Forwards the message across the TCP link to the other local cluster
protected void	forwardToCoord(Message msg) Wraps the message annd sends it to the current coordinator
protected View	generateGlobalView(View local_view, View remote_view)
protected View	generateGlobalView(View local_view, View remote_view, boolean merge)
java.lang.String	getBridgeView()
java.lang.String	getGlobalView()
java.lang.String	getLocalView()
java.lang.String	getRemoteView()
protected java.lang.Object	handleUpEvent(Message msg, RELAY.RelayHeader hdr)
protected void	handleView(View view)
void	init() Called after instance has been created (null constructor) and before protocol is started.
protected java.lang.Object	installView(byte[] buf, int offset, int length)
protected boolean	isLocal(Address dest) Does the payload match the 'site' ID.
protected void	sendOnLocalCluster(byte[] buf, int offset, int length)
protected void	sendViewOnLocalCluster(java.util.List<Address> destinations, byte[] buffer)
protected void	sendViewOnLocalCluster(RELAY.ViewData data, boolean use_seperate_thread, java.util.List<Address> new_mbrs)
protected void	sendViewOnLocalCluster(View remote_view, View global_view, boolean use_seperate_thread, java.util.List<Address> new_mbrs)
protected void	sendViewToRemote(RELAY.ViewData view_data, boolean use_seperate_thread)
void	setRelay(boolean relay)
protected void	startRemoteViewFetcher()
void	stop() This method is called on a Channel.disconnect().
protected void	stopRemoteViewFetcher()
java.lang.Object	up(Event evt) An event was received from the layer below.
void	up(MessageBatch batch) Sends up a multiple messages in a MessageBatch.

Methods inherited from class org.jgroups.stack.Protocol

accept, afterCreationHook, destroy, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getDownServices, getId, getIdsAbove, getLevel, getLog, getName, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getUpServices, getValue, isErgonomics, level, parse, printStats, providedDownServices, providedUpServices, requiredDownServices, requiredUpServices, resetStatistics, resetStats, setDownProtocol, setErgonomics, setId, setLevel, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, start, statsEnabled

Methods inherited from class java.lang.Object

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

Field Detail

site

protected java.lang.String site

bridge_props

protected java.lang.String bridge_props

bridge_name

protected java.lang.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 java.util.concurrent.Future<?> remote_view_fetcher_future

SITE_ID

protected static final byte[] SITE_ID

Constructor Detail

RELAY

public RELAY()

Method Detail

setRelay

public void setRelay(boolean relay)

getLocalView

public java.lang.String getLocalView()

getBridgeView

public java.lang.String getBridgeView()

getRemoteView

public java.lang.String getRemoteView()

getGlobalView

public java.lang.String getGlobalView()

init

public void init()
          throws java.lang.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:

java.lang.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 java.lang.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 java.lang.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

handleUpEvent

protected java.lang.Object handleUpEvent(Message msg,
                                         RELAY.RelayHeader hdr)

up

public void up(MessageBatch batch)

Description copied from class: Protocol

Sends up a multiple messages in a MessageBatch. The sender of the batch is always the same, and so is the destination (null == multicast messages). Messages in a batch can be OOB messages, regular messages, or mixed messages, although the transport itself will create initial MessageBatches that contain only either OOB or regular messages.

The default processing below sends messages up the stack individually, based on a matching criteria (calling Protocol.accept(org.jgroups.Message)), and - if true - calls Protocol.up(org.jgroups.Event) for that message and removes the message. If the batch is not empty, it is passed up, or else it is dropped.

Subclasses should check if there are any messages destined for them (e.g. using MessageBatch.getMatchingMessages(short,boolean)), then possibly remove and process them and finally pass the batch up to the next protocol. Protocols can also modify messages in place, e.g. ENCRYPT could decrypt all encrypted messages in the batch, not remove them, and pass the batch up when done.

Overrides:

up in class Protocol

Parameters:

batch - The message batch

handleView

protected void handleView(View view)

installView

protected java.lang.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(View remote_view,
                                      View global_view,
                                      boolean use_seperate_thread,
                                      java.util.List<Address> new_mbrs)

sendViewOnLocalCluster

protected void sendViewOnLocalCluster(RELAY.ViewData data,
                                      boolean use_seperate_thread,
                                      java.util.List<Address> new_mbrs)

sendViewOnLocalCluster

protected void sendViewOnLocalCluster(java.util.List<Address> destinations,
                                      byte[] buffer)

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()