org.modeshape.clustering
Class ClusteredObservationBus

java.lang.Object
  org.modeshape.clustering.ClusteredObservationBus

All Implemented Interfaces:

Observable, ObservationBus, Observer

public class ClusteredObservationBus
extends Object
implements ObservationBus

An implementation of a cluster-aware ObservationBus.

Nested Class Summary

protected class	ClusteredObservationBus.Listener
protected class	ClusteredObservationBus.Receiver

Field Summary

protected AtomicBoolean	isOpen Flag that dictates whether this bus has connected to the cluster.
protected static Logger	LOGGER
protected AtomicBoolean	multipleAddressesInCluster Flag that dictates whether there are multiple participants in the cluster; if not, then the changes are propogated only to the local observers.
protected ChangeObservers	observers The list of Observer instances that should receive events from the bus.

Constructor Summary

ClusteredObservationBus()

Method Summary

protected static Changes	deserialize(byte[] data)
String	getClusterName() Get the name of the JGroups cluster.
String	getConfiguration() Get the configuration for JGroups.
boolean	hasObservers() Determine whether this particular bus currently has any observers.
boolean	isStarted() Return whether this bus has been started and not yet shut down.
protected org.jgroups.JChannel	newChannel(String configuration) A method that is used to instantiate the JChannel object with the supplied configuration.
void	notify(Changes changes) Method that is called for each set of changes from the Observable instance(s) with which this observer is registered.
boolean	register(Observer observer) Register the supplied observer.
protected static byte[]	serialize(Changes changes)
void	setClusterName(String clusterName) Set the name of the JGroups cluster.
void	setConfiguration(String configuration) Set the JGroups configuration, which may be a string that refers to a resource on the classpath, the path of the local configuration, the URL to the configuration file, or the configuration specified using the newer-style XML form or older-style string form.
void	shutdown() Unregister all registered observers, and mark this as no longer accepting new registered observers.
void	start() Prepare this bus for operation by starting any resources.
boolean	unregister(Observer observer) Unregister the supplied observer.

Methods inherited from class java.lang.Object

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

Field Detail

LOGGER

protected static final Logger LOGGER

observers

protected final ChangeObservers observers

The list of Observer instances that should receive events from the bus. These Observer objects are all local.

isOpen

protected final AtomicBoolean isOpen

Flag that dictates whether this bus has connected to the cluster.

multipleAddressesInCluster

protected final AtomicBoolean multipleAddressesInCluster

Flag that dictates whether there are multiple participants in the cluster; if not, then the changes are propogated only to the local observers.

Constructor Detail

ClusteredObservationBus

public ClusteredObservationBus()

Method Detail

getConfiguration

public String getConfiguration()

Get the configuration for JGroups. This configuration may be a string that refers to a resource on the classpath, the path of the local configuration, the URL to the configuration file, or the configuration specified using the newer-style XML form or older-style string form.

Returns:

the location of the JGroups configuration, or null if no configuration has been defined

setConfiguration

public void setConfiguration(String configuration)

Set the JGroups configuration, which may be a string that refers to a resource on the classpath, the path of the local configuration, the URL to the configuration file, or the configuration specified using the newer-style XML form or older-style string form.

Parameters:

configuration - the relative path to a classpath resource, path to a local file, URL to the configuration file, or the configuration specified using the newer-style XML form or older-style string form.

Throws:

IllegalStateException - if this method is called after this bus has been started but before it has been shutdown

getClusterName

public String getClusterName()

Get the name of the JGroups cluster.

Returns:

the cluster name, or null if the cluster name was not yet defined

See Also:

JChannel.connect(String)

setClusterName

public void setClusterName(String clusterName)

Set the name of the JGroups cluster. This must be called with a non-null cluster name before start() is called.

Parameters:

clusterName - Sets clusterName to the specified value.

Throws:

IllegalStateException - if this method is called after this bus has been started but before it has been shutdown

See Also:

JChannel.connect(String)

start

public void start()

Prepare this bus for operation by starting any resources.

Specified by:

start in interface ObservationBus

See Also:

ObservationBus.start()

newChannel

protected org.jgroups.JChannel newChannel(String configuration)
                                   throws org.jgroups.ChannelException

A method that is used to instantiate the JChannel object with the supplied configuration. Subclasses can override this method to specialize this behavior.

Parameters:

configuration - the configuration; may be null or empty string, if the default configuration should be used

Returns:

the JChannel instance; never null

Throws:

org.jgroups.ChannelException - if there is a problem creating the new channel object

notify

public void notify(Changes changes)

Method that is called for each set of changes from the Observable instance(s) with which this observer is registered.

Specified by:

notify in interface Observer

Parameters:

changes - the changes that are being published

See Also:

Observer.notify(org.modeshape.graph.observe.Changes)

register

public boolean register(Observer observer)

Register the supplied observer. This method does nothing if the observer reference is null.

Specified by:

register in interface Observable

Parameters:

observer - the observer to be added; may be null

Returns:

true if the observer was added, or false if the observer was null, if the observer was already registered, or if the observer could not be added

See Also:

Observable.register(org.modeshape.graph.observe.Observer)

unregister

public boolean unregister(Observer observer)

Unregister the supplied observer. This method does nothing if the observer reference is null.

Specified by:

unregister in interface Observable

Parameters:

observer - the observer to be removed; may not be null

Returns:

true if the observer was removed, or false if the observer was null or if the observer was not registered on this source

See Also:

Observable.unregister(org.modeshape.graph.observe.Observer)

hasObservers

public boolean hasObservers()

Determine whether this particular bus currently has any observers.

Specified by:

hasObservers in interface ObservationBus

Returns:

true if there is at least one observer, or false otherwise

See Also:

ObservationBus.hasObservers()

isStarted

public boolean isStarted()

Return whether this bus has been started and not yet shut down.

Returns:

true if start() has been called but shutdown() has not, or false otherwise

shutdown

public void shutdown()

Unregister all registered observers, and mark this as no longer accepting new registered observers.

Specified by:

shutdown in interface ObservationBus

See Also:

ObservationBus.shutdown()

serialize

protected static byte[] serialize(Changes changes)
                           throws Exception

Throws:

Exception

deserialize

protected static Changes deserialize(byte[] data)
                              throws Exception

Throws:

Exception