commonj.work
Interface RemoteWorkItem

All Superinterfaces:
WorkItem

public interface RemoteWorkItem
extends WorkItem

If a Work instance is serializable and the WorkManager implementation supports Remoteable WorkManager then the Work can be sent to a remote member of the application cluster for execution. This allows serializable Works to be executed on any member of the J2EE cluster containing the application. Subsequent scheduleWork calls will result in the Works being load balanced over the available members in the cluster using a vendor specific algorithm.

Clearly, if this is the case then the Work object supplied to scheduleWork cannot be used to interrogate the result when the Work completes as it was a copy that was executed on the remote JVM. The Work instance is copied and marshalled to the remote JVM where it is executed and then a copy of the Work instance is send back to the JVM that called scheduleWork. This returned copy is then available using the getResult() method.

If the application wants to send multiple Work objects to the same remote JVM then it should schedule Work on a resource-ref obtained WorkManager and then schedule subsequent Work objectgs using the WorkManager obtained from the getPinnedWorkManager() method. This is called a pinned WorkManager. This allows affinity to the same remote JVM to be maintained. If the remote JVM fails then subsequent calls to scheduleWork on the pinned WorkManager will fail with a WorkRejectedException once the failure has been detected.

If a remote JVM containing pending Works fails then these Works are marked as complete with a status of rejected.


Method Summary
 WorkManager getPinnedWorkManager()
          This returns a pinned WorkManager which represents the JVM that was used to execute this Work.
 Work getResult()
          This returns the Work once the Remote Work is completed.
 void release()
          Calls the remote Work object's Work.release() method.
 
Methods inherited from interface commonj.work.WorkItem
getStatus
 

Method Detail

getResult

public Work getResult()
               throws WorkException
This returns the Work once the Remote Work is completed. If the Work threw an exception during run then the exception is rethrown here.

Returns:
the completed Work or null if the Work is not yet complete.
WorkException

release

public void release()
Calls the remote Work object's Work.release() method. It instructs the Work associated with this RemoteWorkItem to 'stop' voluntarily. If the work has already stopped then this has no effect. The WorkItem.getStatus() can be used to determine whether it has stopped or not but the Work can always stop just after getStatus returns 'still working'. The best way to wait for such Works to release is using the WorkManager.waitForAll(java.util.Collection, long) API.


getPinnedWorkManager

public WorkManager getPinnedWorkManager()
This returns a pinned WorkManager which represents the JVM that was used to execute this Work. This allows subsequent remote Works to be sent to the same JVM as the one that was used to execute this WorkItem. If the remote JVM fails then subsequent scheduleWorks on this WorkManager will fail with a rejected exception even if the remote JVM restarts. The pinned WorkManager is associated with the JVM instance that was running as opposed to any future JVM instance.

Returns:
the WorkManager associated with the JVM that was used to execute this RemoteWorkItem


Copyright BEA Systems, Inc. and International Business Machines Corp 2003. All rights reserved.