com.sun.enterprise.ee.cms.impl.jxta
Class GroupHandleImpl

java.lang.Object
  extended by com.sun.enterprise.ee.cms.impl.jxta.GroupHandleImpl
All Implemented Interfaces:
GroupHandle

public final class GroupHandleImpl
extends Object
implements GroupHandle

Implementation of GroupHandle interface.

Version:
$Revision: 1.13 $
Author:
Shreedhar Ganapathy Date: Jan 12, 2004

Constructor Summary
GroupHandleImpl(String groupName, String serverToken)
           
 
Method Summary
 List<String> getAllCurrentMembers()
          returns a List containing the current group membership including spectator members.
 List<String> getAllCurrentMembersWithStartTimes()
          returns a List of strings containing the current group membership including spectator members.
 List<String> getCurrentAliveOrReadyMembers()
          * returns only the members that are in ALIVE or READY state
 List<String> getCurrentCoreMembers()
          returns a List containing the current core members in the group.
 List<String> getCurrentCoreMembersWithStartTimes()
          returns a List of strings containing the current core members in the group.
 DistributedStateCache getDistributedStateCache()
          returns a DistributedStateCache object that provides the ability to set and retrieve CachedStates.
 String getGroupLeader()
          Return the leader of the group
 MemberStates getMemberState(String member)
          API for giving the state of the member Calls #getMemberState(String, long, long) with implementation default values for threshold and timeout.
 MemberStates getMemberState(String member, long threshold, long timeout)
          Returns the state of the member.
 List<String> getSuspectList()
           
 boolean isFenced(String componentName, String memberToken)
          Provides the status of a member component's fence, if any.
 boolean isGroupLeader()
          This is a check to find out if this peer is a group leader.
 boolean isMemberAlive(String memberToken)
          Checks if a member is alive
 void lowerFence(String componentName, String failedMemberToken)
          Enables the caller to lower a logical fence that was earlier raised on a target member component.
 void raiseFence(String componentName, String failedMemberToken)
          Enables the caller to raise a logical fence on a specified target member token's component.
 void sendMessage(List<String> targetServerTokens, String targetComponentName, byte[] message)
          Sends a message to a list of members in the group.
 void sendMessage(String componentName, byte[] message)
          Sends a message to all members of the Group.
 void sendMessage(String targetServerToken, String targetComponentName, byte[] message)
          Sends a message to a single member of the group Expects a targetServerToken representing the recipient member's id, the target component name in the target recipient member, and a byte array as parameter carrying the payload.
 String toString()
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

GroupHandleImpl

public GroupHandleImpl(String groupName,
                       String serverToken)
Method Detail

sendMessage

public void sendMessage(String componentName,
                        byte[] message)
                 throws GMSException
Sends a message to all members of the Group. Expects a byte array as parameter carrying the payload.

Specified by:
sendMessage in interface GroupHandle
Parameters:
componentName - Destination component in remote members.
message - Payload in byte array to be delivered to the destination.
Throws:
GMSException - - any exception while sending message wrapped into GMSException

sendMessage

public void sendMessage(String targetServerToken,
                        String targetComponentName,
                        byte[] message)
                 throws GMSException
Sends a message to a single member of the group Expects a targetServerToken representing the recipient member's id, the target component name in the target recipient member, and a byte array as parameter carrying the payload. Specifying a null component name would result in the message being delivered to all registered components in the target member instance.

Specified by:
sendMessage in interface GroupHandle
Parameters:
targetServerToken - destination member's identification
targetComponentName - destination member's target component
message - Payload in byte array to be delivered to the destination.
Throws:
GMSException - - any exception while sending message wrapped into GMSException

sendMessage

public void sendMessage(List<String> targetServerTokens,
                        String targetComponentName,
                        byte[] message)
                 throws GMSException
Description copied from interface: GroupHandle
Sends a message to a list of members in the group. An empty list would have the same effect as sending the message to the entire group

Specified by:
sendMessage in interface GroupHandle
Parameters:
targetServerTokens - List of target server tokens
targetComponentName - a component in the target members to which message is addressed.
message - - the payload
Throws:
GMSException - - any exception while sending message wrapped into GMSException

getDistributedStateCache

public DistributedStateCache getDistributedStateCache()
returns a DistributedStateCache object that provides the ability to set and retrieve CachedStates.

Specified by:
getDistributedStateCache in interface GroupHandle
Returns:
DistributedStateCache
See Also:
DistributedStateCache

getCurrentCoreMembers

public List<String> getCurrentCoreMembers()
returns a List containing the current core members in the group.

Specified by:
getCurrentCoreMembers in interface GroupHandle
Returns:
List a List of member token ids pertaining to core members

getAllCurrentMembers

public List<String> getAllCurrentMembers()
returns a List containing the current group membership including spectator members.

Specified by:
getAllCurrentMembers in interface GroupHandle
Returns:
List a List of member token ids pertaining to all members

getCurrentCoreMembersWithStartTimes

public List<String> getCurrentCoreMembersWithStartTimes()
Description copied from interface: GroupHandle
returns a List of strings containing the current core members in the group. Each entry contains a "::" delimiter after the member token id. After the delimited is a string representation of the long value that stands for that member's startup timestamp.

Specified by:
getCurrentCoreMembersWithStartTimes in interface GroupHandle
Returns:
List

getAllCurrentMembersWithStartTimes

public List<String> getAllCurrentMembersWithStartTimes()
Description copied from interface: GroupHandle
returns a List of strings containing the current group membership including spectator members. Each entry contains a "::" delimiter after the member token id. After the delimited is a string representation of the long value that stands for that member's startup timestamp.

Specified by:
getAllCurrentMembersWithStartTimes in interface GroupHandle
Returns:
List

raiseFence

public void raiseFence(String componentName,
                       String failedMemberToken)
                throws GMSException
Enables the caller to raise a logical fence on a specified target member token's component. This API is directly called only when a component is raising a fence itself and not as part of acquiring a signal. If this is part of acquiring a signal, then the call should be to signal.acquire() which encompasses raising a fence and potentially other state updates.

Failure Fencing is a group-wide protocol that, on one hand, requires members to update a shared/distributed datastructure if any of their components need to perform operations on another members' corresponding component. On the other hand, the group-wide protocol requires members to observe "Netiquette" during their startup so as to check if any of their components are being operated upon by other group members. Typically this check is performed by the respective components themselves. See the isFenced() method below for this check. When the operation is completed by the remote member component, it removes the entry from the shared datastructure. See the lowerFence() method below.

Raising the fence, places an entry into a distributed datastructure that is accessed by other members during their startup

Specified by:
raiseFence in interface GroupHandle
Parameters:
componentName -
failedMemberToken -
Throws:
GMSException

lowerFence

public void lowerFence(String componentName,
                       String failedMemberToken)
                throws GMSException
Enables the caller to lower a logical fence that was earlier raised on a target member component. This is typically done when the operation being performed on the target member component has now completed. This api is directly called only by a component that is lowering a fence directly and not as part of releasing a signal. If the operation is to release a signal, then the appropriate call is to signal.release() which encompasses lowering the fence and other cleanups.

Specified by:
lowerFence in interface GroupHandle
Parameters:
componentName - target member component
failedMemberToken -
Throws:
GMSException

isFenced

public boolean isFenced(String componentName,
                        String memberToken)
Provides the status of a member component's fence, if any.

This check is mandatorily done at the time a member component is in the process of starting(note that at this point we assume that this member failed in its previous lifetime).

The boolean value returned would indicate if this member component is being recovered by any other member. The criteria for returning a boolean "true" is that this componentName-memberToken combo is present as a value for any key in the GMS DistributedStateCache. If a true is returned, for instance, this could mean that the client component should continue its startup without attempting to perform its own recovery operations.

The criteria for returning a boolean "false" is that the componentId-memberTokenId combo is not present in the list of values in the DistributedStateCache.If a boolean "false" is returned, this could mean that the client component can continue with its lifecycle startup per its normal startup policies.

Specified by:
isFenced in interface GroupHandle
Parameters:
componentName -
memberToken -
Returns:
boolean

isMemberAlive

public boolean isMemberAlive(String memberToken)
Description copied from interface: GroupHandle
Checks if a member is alive

Specified by:
isMemberAlive in interface GroupHandle
Returns:
boolean

getGroupLeader

public String getGroupLeader()
Description copied from interface: GroupHandle
Return the leader of the group

Specified by:
getGroupLeader in interface GroupHandle
Returns:
String representing the member identity token of the group leader

isGroupLeader

public boolean isGroupLeader()
Description copied from interface: GroupHandle
This is a check to find out if this peer is a group leader.

Specified by:
isGroupLeader in interface GroupHandle
Returns:
true if this peer is the group leader

getSuspectList

public List<String> getSuspectList()

toString

public String toString()
Overrides:
toString in class Object

getCurrentAliveOrReadyMembers

public List<String> getCurrentAliveOrReadyMembers()
Description copied from interface: GroupHandle
* returns only the members that are in ALIVE or READY state

Specified by:
getCurrentAliveOrReadyMembers in interface GroupHandle
Returns:
List

getMemberState

public MemberStates getMemberState(String member)
Description copied from interface: GroupHandle
API for giving the state of the member Calls #getMemberState(String, long, long) with implementation default values for threshold and timeout.

Specified by:
getMemberState in interface GroupHandle
Returns:
the state of the member.

getMemberState

public MemberStates getMemberState(String member,
                                   long threshold,
                                   long timeout)
Description copied from interface: GroupHandle
Returns the state of the member. The parameters threshold and timeout enable the caller to tune this lookup between accuracy and time it will take to complete the call. It is lowest cost to just return the local computed concept for a member's state. threshold parameter controls this. If the local state is stale, then the timeout parameter enables one to control how long they are willing to wait for more accurate state information from the member itself.

Specified by:
getMemberState in interface GroupHandle
threshold - allows caller to specify how up-to-date the member state information has to be. The larger this value, the better chance that this method just returns the local concept of this member's state. The smaller this value, the better chance that the local state is not fresh enough and the method will find out directly from the instance what its current state is.
timeout - is the time for which the caller instance should wait to get the state from the concerned member via a network call. if timeout and threshold are both 0, then the default values are used if threshold is 0, then a network call is made to get the state of the member if timeout is 0, then the caller instance checks for the state of the member stored with it within the given threshold
Returns:
the state of the member Returns UNKNOWN when the local state for the member is considered stale (determined by threshold value) and the network invocation to get the member state times out before getting a reply from the member of what its state is.


Copyright © 2003 Copyright 2004 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.