jgroup.relacs.gm
Class MembershipLayer

java.lang.Object
  jgroup.relacs.gm.MembershipLayer

All Implemented Interfaces:

Layer, Layer.FinalizeLayer, MembershipService, EventTags, DispatcherListener

public final class MembershipLayer
extends java.lang.Object
implements MembershipService, DispatcherListener, EventTags

The MembershipLayer class implements the group membership service interface and provide membership events to listeners.

Since:

Jgroup 2.2

Author:

Alberto Montresor, Hein Meling

Nested Class Summary

Nested classes/interfaces inherited from interface jgroup.core.Layer

Layer.FinalizeLayer

Field Summary

Fields inherited from interface jgroup.relacs.events.EventTags

DAEMON_FAILURE_EVENT, DELIVERY_ACK, DELIVERY_EVENT, INSTALL_ACK, INSTALL_EVENT, JOIN_REQUEST, LEAVE_REQUEST, MEMBER_LEFT_EVENT, MULTICAST_REQUEST, PREPARE_ACK, PREPARE_EVENT

Method Summary

void	addListener(java.lang.Object listener) Add a listener object for this layer to provide upcalls to, in response to membership events.
void	complete(java.lang.Object server) Post initialization of the MembershipLayer; invoked once all group manager layers have been constructed.
int[]	eventTypes() Returns the set of event types supported by this listener.
int	getGid() Returns the group identifier.
static MembershipLayer	getLayer(DispatcherService dispatcher)
int	getMemberIndex() Position index of this member in the array containing the local members of the current view.
MemberTable	getMemberTable() Returns a MemberTable helper object that will be notified of changes in the membership.
MemberId	getMyIdentifier() Returns the member identifier of the local member.
int	getViewIndex() Position index of this member in the array containing the members of the current view.
boolean	isJoining() Returns true if the GroupManager is in the process of joining some group.
boolean	isLeader() Returns true if the local member is the group leader.
boolean	isMember() Returns true if the GroupManager is member of some group.
boolean	isMemberOrJoining() Returns true if the GroupManager is member of some group or is in the process of joining some group.
boolean	isUnused()
void	join() Requests to join the default group associated with the Jgroup daemon.
void	join(int gid) Requests to join a group identified by groupId.
void	leave() Request to leave a group.
int	members() Return the number of members of this group.
void	notifyEvent(Event event) This method is invoked by a dispatcher to notify a listener about an event.
java.lang.String	toString() Returns a string representation of this object; currently only the status and group identifier.

Methods inherited from class java.lang.Object

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

Method Detail

getLayer

public static MembershipLayer getLayer(DispatcherService dispatcher)
                                throws JgroupException

Throws:

JgroupException

addListener

public void addListener(java.lang.Object listener)

Add a listener object for this layer to provide upcalls to, in response to membership events.

Specified by:

addListener in interface Layer

Parameters:

listener - An Object representation of the listener interface. This will typically be cast to the appropriate listener interface type after checking the type with the instanceof operator.

See Also:

Layer.addListener(java.lang.Object)

complete

public void complete(java.lang.Object server)
              throws JgroupException

Post initialization of the MembershipLayer; invoked once all group manager layers have been constructed. This method is defined in the FinalizeLayer inherited through the MembershipSerivce.

This method is used to determine if the provided server should join the group automatically, as soon as the group manager layer stack has been completed. By default, automatic join is disabled. To enable auto join you must configure it in the applications.xml file.

Specified by:

complete in interface Layer.FinalizeLayer

Parameters:

server - The server using a layer implementing the FinalizeLayer interface.

Throws:

JgroupException - Thrown if the layer could not be completed.

join

public void join()
          throws JgroupException

Description copied from interface: MembershipService

Requests to join the default group associated with the Jgroup daemon.

Each Jgroup daemon has a default group. If a Jgroup daemon does not need to be shared by multiple groups, the application servers may simply join the default group without having to specify group identifiers.

Specified by:

join in interface MembershipService

Throws:

JgroupException - Raised if the membership service receives a request to join a group to which it is already a member.

join

public void join(int gid)
          throws JgroupException

Description copied from interface: MembershipService

Requests to join a group identified by groupId.

Specified by:

join in interface MembershipService

Parameters:

gid - Non-negative integer identifying the group.

Throws:

JgroupException - Raised if the membership service receives a request to join a group to which it is already a member.

leave

public void leave()
           throws JgroupException

Description copied from interface: MembershipService

Request to leave a group. Note that an object member may receive event notifications such as view installations for a group even after having requested to leave the group itself. However, the member will eventually leave the group. When this happens, its hasLeft method is invoked. After this invocation, the member will not receive any further event notification related to the group.

Specified by:

leave in interface MembershipService

Throws:

JgroupException - Rasied if the server is not member of any group, or is already leaving its current group.

isMember

public boolean isMember()

Description copied from interface: MembershipService

Returns true if the GroupManager is member of some group. Otherwise, false is returned.

Specified by:

isMember in interface MembershipService

isJoining

public boolean isJoining()

Description copied from interface: MembershipService

Returns true if the GroupManager is in the process of joining some group. Otherwise, false is returned.

Specified by:

isJoining in interface MembershipService

isMemberOrJoining

public boolean isMemberOrJoining()

Description copied from interface: MembershipService

Returns true if the GroupManager is member of some group or is in the process of joining some group. Otherwise, false is returned.

Specified by:

isMemberOrJoining in interface MembershipService

isUnused

public boolean isUnused()

isLeader

public boolean isLeader()

Description copied from interface: MembershipService

Returns true if the local member is the group leader.

Specified by:

isLeader in interface MembershipService

getMyIdentifier

public MemberId getMyIdentifier()

Description copied from interface: MembershipService

Returns the member identifier of the local member.

Specified by:

getMyIdentifier in interface MembershipService

getGid

public int getGid()

Description copied from interface: MembershipService

Returns the group identifier.

Specified by:

getGid in interface MembershipService

getMemberTable

public MemberTable getMemberTable()

Description copied from interface: MembershipService

Returns a MemberTable helper object that will be notified of changes in the membership. This is used to provide application developers with additional information about members of their current view.

Specified by:

getMemberTable in interface MembershipService

members

public int members()

Description copied from interface: MembershipService

Return the number of members of this group.

Specified by:

members in interface MembershipService

getViewIndex

public int getViewIndex()

Description copied from interface: MembershipService

Position index of this member in the array containing the members of the current view.

Specified by:

getViewIndex in interface MembershipService

getMemberIndex

public int getMemberIndex()

Description copied from interface: MembershipService

Position index of this member in the array containing the local members of the current view.

Specified by:

getMemberIndex in interface MembershipService

eventTypes

public int[] eventTypes()

Description copied from interface: DispatcherListener

Returns the set of event types supported by this listener. Legal event types are given in the EventTags interface.

Specified by:

eventTypes in interface DispatcherListener

notifyEvent

public void notifyEvent(Event event)

Description copied from interface: DispatcherListener

This method is invoked by a dispatcher to notify a listener about an event.

Specified by:

notifyEvent in interface DispatcherListener

Parameters:

event - The Event object to be processed.

toString

public java.lang.String toString()

Returns a string representation of this object; currently only the status and group identifier.

Overrides:

toString in class java.lang.Object