org.jboss.ha.framework.server
Class HATarget

java.lang.Object
  org.jboss.ha.framework.server.HATarget

All Implemented Interfaces:

DistributedReplicantManager.ReplicantListener

public class HATarget
extends Object
implements DistributedReplicantManager.ReplicantListener

Control point representing a clustered service. Works with the DistributedReplicantManager to makes available a list of replicants (objects used to identify remote service endpoints around the cluster) for the service. Guards access to the service via the invocationsAllowed() and setInvocationsAuthorization(int) methods.

Version:

$Revision: 69398 $

Revisions:

2002/01/13: Bill Burke

1. Initial revision

Author:

bill@burkecentral.com

Field Summary

protected int	allowInvocationsStatus
protected int	clusterViewId
static int	DISABLE_INVOCATIONS Argument to setInvocationsAuthorization(int) that indicates invocationsAllowed() should return false.
static int	ENABLE_INVOCATIONS Argument to setInvocationsAuthorization(int) that indicates invocationsAllowed() should return true.
protected CountDownLatch	latch
protected org.jboss.logging.Logger	log
static int	MAKE_INVOCATIONS_WAIT Argument to setInvocationsAuthorization(int) that indicates calls to invocationsAllowed() should block until a different value is passed to setInvocationsAuthorization(int).
protected HAPartition	partition
protected String	replicantName
protected ArrayList	replicants
protected Serializable	target

Constructor Summary

HATarget(HAPartition partition, String replicantName, Serializable target, int allowInvocations)
Creates a new HATarget.

Method Summary

protected void	cleanExistenceInCurrentHAPartition() Unregister's with the partition's DistributedReplicantManager.
void	destroy() Removes the local node from the distributed registry of nodes providing the service and causes invocationsAllowed() to return false.
void	disable() Removes the local node from the distributed registry of nodes providing the service.
HAPartition	getAssociatedPartition()
long	getCurrentViewId() Gets the current view id for the clustered service.
ArrayList	getReplicants() Gets the replicants for the clustered service.
protected void	init() Deprecated. this will be removed in the next major release
boolean	invocationsAllowed() Returns whether invocations on the target service are currently allowed on this node.
protected void	releaseCurrentLatch() Releases any latch blocking threads in invocationsAllowed().
void	replicantsChanged(String key, List newReplicants, int newReplicantsViewId, boolean merge) Callback called when the content/list of replicant for a given replicant key has changed
void	setInvocationsAuthorization(int status) Sets the behavior expected from invocationsAllowed().
String	toString()
protected void	updateHAPartition(HAPartition partition) Associates this target with the given partition, registering with the partition's DistributedReplicantManager.

Methods inherited from class java.lang.Object

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

Field Detail

DISABLE_INVOCATIONS

public static final int DISABLE_INVOCATIONS

Argument to setInvocationsAuthorization(int) that indicates invocationsAllowed() should return false.

See Also:

Constant Field Values

MAKE_INVOCATIONS_WAIT

public static final int MAKE_INVOCATIONS_WAIT

Argument to setInvocationsAuthorization(int) that indicates calls to invocationsAllowed() should block until a different value is passed to setInvocationsAuthorization(int).

See Also:

Constant Field Values

ENABLE_INVOCATIONS

public static final int ENABLE_INVOCATIONS

Argument to setInvocationsAuthorization(int) that indicates invocationsAllowed() should return true.

See Also:

Constant Field Values

replicantName

protected String replicantName

replicants

protected ArrayList replicants

partition

protected HAPartition partition

log

protected org.jboss.logging.Logger log

clusterViewId

protected int clusterViewId

target

protected Serializable target

allowInvocationsStatus

protected int allowInvocationsStatus

latch

protected CountDownLatch latch

Constructor Detail

HATarget

public HATarget(HAPartition partition,
                String replicantName,
                Serializable target,
                int allowInvocations)
         throws Exception

Creates a new HATarget.

Parameters:

partition - the HAPartition for the service's cluster

replicantName - the name of the service

target - the service's replicant

allowInvocations - true if invocationsAllowed() should return true immediately; false if not

Throws:

Exception

Method Detail

toString

public String toString()

Overrides:

toString in class Object

getCurrentViewId

public long getCurrentViewId()

Gets the current view id for the clustered service.

destroy

public void destroy()

Removes the local node from the distributed registry of nodes providing the service and causes invocationsAllowed() to return false.

disable

public void disable()

Removes the local node from the distributed registry of nodes providing the service. After this call, the HATarget can still be queried for view change, etc. but the local node's instance of the service is no longer registered with the cluster.

NOTE: Calling this method does not cause invocationsAllowed() to return false. Use destroy() unless your application needs to separately control the two aspects of shutting down a clustered service.

getReplicants

public ArrayList getReplicants()

Gets the replicants for the clustered service. A replicant is a service-specific object, typically something that represents a remote service endpoint for the service on a particular cluster node. Examples include an RMI stub, a JBoss Remoting InvokerLocator or an HTTP URL.

setInvocationsAuthorization

public void setInvocationsAuthorization(int status)

Sets the behavior expected from invocationsAllowed().

Parameters:

status - ENABLE_INVOCATIONS, DISABLE_INVOCATIONS or MAKE_INVOCATIONS_WAIT

invocationsAllowed

public boolean invocationsAllowed()
                           throws InterruptedException

Returns whether invocations on the target service are currently allowed on this node. Will block if setInvocationsAuthorization(int) has been set to MAKE_INVOCATIONS_WAIT.

Returns:

truee if it is valid to make invocations on the service, false otherwise

Throws:

InterruptedException - if the current thread is interrupted while blocking waiting for MAKE_INVOCATIONS_WAIT

getAssociatedPartition

public HAPartition getAssociatedPartition()

replicantsChanged

public void replicantsChanged(String key,
                              List newReplicants,
                              int newReplicantsViewId,
                              boolean merge)

Description copied from interface: DistributedReplicantManager.ReplicantListener

Callback called when the content/list of replicant for a given replicant key has changed

Specified by:

replicantsChanged in interface DistributedReplicantManager.ReplicantListener

Parameters:

key - The name of the key of the replicant that has changed

newReplicants - The list of new replicants for the give replicant key. This list will be in a consistent order on all cluster nodes on which the current viewId is in effect

newReplicantsViewId - The new replicant view id corresponding to this change

merge - Is the change due to a merge (i.e. the healing of a cluster split)?

init

@Deprecated
protected void init()
             throws Exception

Deprecated. this will be removed in the next major release

Allows subclasses to perform initialization work.

Throws:

Exception

updateHAPartition

protected void updateHAPartition(HAPartition partition)
                          throws Exception

Associates this target with the given partition, registering with the partition's DistributedReplicantManager.

Parameters:

partition - the partition

Throws:

Exception

cleanExistenceInCurrentHAPartition

protected void cleanExistenceInCurrentHAPartition()

Unregister's with the partition's DistributedReplicantManager.

releaseCurrentLatch

protected void releaseCurrentLatch()

Releases any latch blocking threads in invocationsAllowed().