org.modeshape.jcr.clustering

Class ClusteringService

java.lang.Object

org.modeshape.jcr.clustering.ClusteringService

@ThreadSafe
public abstract class ClusteringService
extends Object

ModeShape service which handles sending/receiving messages in a cluster via JGroups. This service is also a LockingService when running in a cluster, relying on JGroups' CENTRAL_LOCK protocol.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	ClusteringService.Listener
protected class	ClusteringService.Receiver

Field Summary

Fields

Modifier and Type	Field and Description
protected org.jgroups.Channel	channel The JGroups channel which will be used to send/receive event across the cluster
protected String	clusterName The name of the cluster (in standalone mode) or the ID of the fork stack (in forked mode)
protected ClusteringService.Listener	listener The listener for channel changes.
protected static Logger	LOGGER
protected ClusteringService.Receiver	receiver The component that will receive the JGroups messages.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ClusteringService(String clusterName)

Method Summary

Modifier and Type	Method and Description
void	addConsumer(MessageConsumer<? extends Serializable> consumer) Adds a new message consumer to this service.
String	clusterName() Returns the name of the cluster which has been configured for this service.
protected Serializable	fromByteArray(byte[] data, ClassLoader classLoader)
org.jgroups.Channel	getChannel() Returns the JGroups channel used for clustered communication.
long	getMaxAllowedClockDelayMillis() Returns the maximum accepted delay in clock time between cluster members.
protected abstract void	init()
boolean	isOpen() Checks if this instance is open or not (open means the JGroups channel has been connected).
int	membersInCluster() Returns the number of members in the cluster.
boolean	multipleMembersInCluster() Checks if the cluster has multiple members.
void	restart() Performs a shutdown/startup sequence.
boolean	sendMessage(Serializable payload) Sends a message of a given type across a cluster.
boolean	shutdown() Shuts down and clears resources held by this service.
static ClusteringService	startForked(org.jgroups.Channel mainChannel) Starts a new clustering service by forking a channel of an existing JGroups channel.
static ClusteringService	startStandalone(String clusterName, org.jgroups.Channel channel) Starts a standalone clustering service which uses the supplied channel.
static ClusteringService	startStandalone(String clusterName, String jgroupsConfig) Starts a standalone clustering service which in turn will start & connect its own JGroup channel.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

LOGGER

protected static final Logger LOGGER

listener

protected final ClusteringService.Listener listener

The listener for channel changes.

receiver

protected final ClusteringService.Receiver receiver

The component that will receive the JGroups messages.

clusterName

protected final String clusterName

The name of the cluster (in standalone mode) or the ID of the fork stack (in forked mode)

channel

protected org.jgroups.Channel channel

The JGroups channel which will be used to send/receive event across the cluster

Constructor Detail

ClusteringService

protected ClusteringService(String clusterName)

Method Detail

restart

public void restart()
             throws Exception

Performs a shutdown/startup sequence.

Throws:

Exception - if anything unexpected fails

addConsumer

public void addConsumer(MessageConsumer<? extends Serializable> consumer)

Adds a new message consumer to this service.

Parameters:

consumer - a MessageConsumer instance.

shutdown

public boolean shutdown()

Shuts down and clears resources held by this service.

Returns:

true if the service has been shutdown or false if it had already been shut down.

isOpen

public boolean isOpen()

Checks if this instance is open or not (open means the JGroups channel has been connected).

Returns:

true if the service is open, false otherwise.

multipleMembersInCluster

public boolean multipleMembersInCluster()

Checks if the cluster has multiple members.

Returns:

true if the cluster has multiple members, false otherwise.

membersInCluster

public int membersInCluster()

Returns the number of members in the cluster.

Returns:

the number of active members

clusterName

public String clusterName()

Returns the name of the cluster which has been configured for this service.

Returns:

a String the name of the cluster; never null

getMaxAllowedClockDelayMillis

public long getMaxAllowedClockDelayMillis()

Returns the maximum accepted delay in clock time between cluster members.

Returns:

the number of milliseconds representing the maximum accepted delay.

sendMessage

public boolean sendMessage(Serializable payload)

Sends a message of a given type across a cluster.

Parameters:

payload - the main body of the message; must not be null

Returns:

true if the send operation was successful, false otherwise

toString

public String toString()

Overrides:

toString in class Object

startStandalone

public static ClusteringService startStandalone(String clusterName,
                                                String jgroupsConfig)

Starts a standalone clustering service which in turn will start & connect its own JGroup channel.

Parameters:

clusterName - the name of the cluster to which the JGroups channel should connect; may not be null

jgroupsConfig - either the path or the XML content of a JGroups configuration file; may not be null

Returns:

a ClusteringService instance, never null

startStandalone

public static ClusteringService startStandalone(String clusterName,
                                                org.jgroups.Channel channel)

Starts a standalone clustering service which uses the supplied channel.

Parameters:

clusterName - the name of the cluster to which the JGroups channel should connect; may not be null

channel - a Channel instance, may not be null

Returns:

a ClusteringService instance, never null

startForked

public static ClusteringService startForked(org.jgroups.Channel mainChannel)

Starts a new clustering service by forking a channel of an existing JGroups channel.

Parameters:

mainChannel - a Channel instance; may not be null.

Returns:

a ClusteringService instance, never null

fromByteArray

protected Serializable fromByteArray(byte[] data,
                                     ClassLoader classLoader)
                              throws IOException,
                                     ClassNotFoundException

Throws:

IOException

ClassNotFoundException

getChannel

public org.jgroups.Channel getChannel()

Returns the JGroups channel used for clustered communication.

Returns:

a Channel instance, never null

init

protected abstract void init()