com.tangosol.coherence.commonj
Class WorkManager

java.lang.Object
  com.tangosol.util.Base
      com.tangosol.coherence.commonj.WorkManager

All Implemented Interfaces:

commonj.work.WorkManager

public class WorkManager
extends Base
implements commonj.work.WorkManager

An implementation of commonj.work.WorkManager based on a joint BEA-IBM specification: "The Timer and Work Manager for Application Servers", which is a foundation of JSR 237: Work Manager for Application Servers.

Implementation notes:

• This WorkManager implementation allows client to request current "work in progress" feedback via getCurrentResult(commonj.work.WorkItem) method.
• The specification does not explicitly specify what response should be if a remote server crashes during an execution. Current implementation uses WORK_COMPLETED with WorkCompletedException as a result. It's important to understand that in a generic case it's impossible to know whether or not a Work has been completed.
If a Work originator Member terminates before the Work gets started, the remote server will still run it.
• Only serializable Work is currently supported.

Note: The WorkManager is a feature of the Coherence Enterprise Edition and Coherence Grid Edition. It cannot be used in a Coherence Standard Edition cluster.

See Also:

WorkManager and Timers: Utilities for J2EE programmers
Timer and Work Manager for Application Servers

Nested Class Summary

protected static class	WorkManager.AbstractWork Base class for Invocable tasks related to the WorkManager.
protected static class	WorkManager.CollectMembershipInfo Invocable task used during handshake, which has to be scheduled immediately.
protected static class	WorkManager.ReleaseWork Invocable task that forces a release for a wrapped Work object.
protected class	WorkManager.RemoteWorkManager RemoteWorkManager is a delegating WorkManager wrapper.
protected static class	WorkManager.RequestStatus Invocable task that requests a status for a given Work.
protected static class	WorkManager.ScheduleWork Invocable task that posts a wrapped Work object to a WorkManager queue.
protected static class	WorkManager.ScheduleWorkRejectedException The ScheduleWorkRejectedException is a WrapperException that carries the information about the rejected Work.
protected static class	WorkManager.SendFeedback Invocable task that delivers a WorkEvent to a WorkListener.
protected class	WorkManager.ServiceListener The member listener for the InvocataionService used by the WorkManager.
protected class	WorkManager.WorkHolder A holder for a Work object that serves as a communication intermediary between a client and a [remote] service.
protected class	WorkManager.WorkObserver The InvocationObserver for all posted work.
protected static class	WorkManager.WorkStatus A WorkStatus object is used to communicate a work execution status back to the caller.

Field Summary

protected InvocationObserver

m_workObserver The ScheduleWork agent observer.

Fields inherited from interface commonj.work.WorkManager

IMMEDIATE, INDEFINITE

Constructor Summary

WorkManager(String sManagerName, int cThreads)
Construct the WorkManager.

Method Summary

void	cancelPostedWork() Cancel all posted work that has not yet completed.
protected Member	chooseServer() Choose a Member to run a next Work at.
protected void	collectMembershipInfo() Inform all the members about this node's role (client or server) and collect the information regarding other nodes' roles
void	disableServer(Member member) Remove a Member from a list of active server nodes and terminate all work posted to that server.
protected int	generateWorkId() Generate a unique (for this WorkManager) work id.
Map	getAcceptedWork() Return a catalog of accepted ScheduleWork tasks as known by the server side keyed by the origin Member where the value is a map of ScheduleWork tasks keyed by the WorkId.
WorkManager.WorkStatus	getCurrentResult(commonj.work.WorkItem item) Retrieve a current WorkStatus (partial result) for a given Work.
Map	getPostedWork() Return a catalog of WorkHolder objects for all posted Work as known by the client side keyed by the corresponding work id.
protected WorkManager.WorkHolder	getPostedWork(long lWorkId) Return a WorkHolder for a posted work with a given id.
Set	getServers() Return a set of Members that run the same Invocation service as this WorkManager in a "server" capacity.
InvocationService	getService() Return an InvocationService used by this WorkManager.
protected void	init(String sManagerName, int cThreads) Initialization.
protected void	initWork(WorkManager.ScheduleWork workAgent) Initialize the remote work agent.
protected void	installMemberListener() Install a MemberListener.
protected void	instantiateWorkObserver() Instantiate a Work observer.
boolean	isServer() Check whether or not this node operates in a "server" mode processing remote Work requests.
static void	main(String[] asArg) Entry point: start a stand-alone WorkManager (server) using the specified name and thread count.
protected void	processFeedback(WorkManager.SendFeedback workFeedback) Process a remote work feedback.
protected Object	processWork(WorkManager.ScheduleWork workAgent) Run the remote work agent.
protected void	releaseWork(WorkManager.ReleaseWork releaseAgent) Release the remote work agent.
protected WorkManager.WorkHolder	removePostedWork(long lWorkId) Remove a WorkHolder for a posted work with a given id.
protected WorkManager.WorkStatus	requestWorkStatus(WorkManager.RequestStatus requestAgent) Obtain current status of the specified Work.
commonj.work.WorkItem	schedule(commonj.work.Work work) Dispatches a Work asynchronously.
commonj.work.WorkItem	schedule(commonj.work.Work work, commonj.work.WorkListener workListener) Dispatches a Work asynchronously.
protected commonj.work.WorkItem	schedule(commonj.work.Work work, commonj.work.WorkListener workListener, Member member) Accepts a Work instance for processing at the specified Member.
protected boolean	updateWork(WorkManager.WorkStatus status) Update a WorkStatus for a work.
boolean	waitForAll(Collection collWorkItems, long lTimeoutMillis) Wait for all WorkItems in the collection to finish.
Collection	waitForAny(Collection collWorkItems, long lTimeoutMillis) Wait for any of the WorkItems in the collection to finish.

Field Detail

m_workObserver

protected InvocationObserver m_workObserver

The ScheduleWork agent observer.

Constructor Detail

WorkManager

public WorkManager(String sManagerName,
                   int cThreads)

Construct the WorkManager.

Parameters:

sManagerName - a unique WorkManager name; there could be one and only one manager per cluster node with this name. This name will also be the name of the underlying InvocationService instance used by the WorkManager. WorkManagers across the cluster that share a common name will form a pool of available WorkManager threads.

cThreads - number of threads dedicated for Work processing; if this value is zero, the WorkManager will be in a "client" role only

Method Detail

init

protected void init(String sManagerName,
                    int cThreads)

Initialization.

installMemberListener

protected void installMemberListener()

Install a MemberListener.

instantiateWorkObserver

protected void instantiateWorkObserver()

Instantiate a Work observer.

collectMembershipInfo

protected void collectMembershipInfo()

Inform all the members about this node's role (client or server) and collect the information regarding other nodes' roles

schedule

public commonj.work.WorkItem schedule(commonj.work.Work work)
                               throws commonj.work.WorkException

Dispatches a Work asynchronously. The work is dispatched and the method returns immediately.

At-most-once semantics are provided. If the server fails then the Work will not be executed on restart.

Specified by:

schedule in interface commonj.work.WorkManager

Parameters:

work - the Work to execute.

Returns:

the WorkItem representing the asynchronous work; since the Work must be serializable, a RemoteWorkItem is always returned

Throws:

commonj.work.WorkException - thrown if queuing this up results in an exception

schedule

public commonj.work.WorkItem schedule(commonj.work.Work work,
                                      commonj.work.WorkListener workListener)
                               throws commonj.work.WorkException

Dispatches a Work asynchronously. The work is dispatched and the method returns immediately.

At-most-once semantics are provided. If the server fails then the Work will not be executed on restart.

Specified by:

schedule in interface commonj.work.WorkManager

Parameters:

work - the Work to execute

workListener - an optional WorkListener which is used to inform the application of the progress of a Work

Returns:

the WorkItem representing the asynchronous work; since the Work must be serializable, a RemoteWorkItem is always returned

Throws:

commonj.work.WorkException - thrown if queuing this up results in an exception

schedule

protected commonj.work.WorkItem schedule(commonj.work.Work work,
                                         commonj.work.WorkListener workListener,
                                         Member member)
                                  throws commonj.work.WorkException

Accepts a Work instance for processing at the specified Member.

Throws:

commonj.work.WorkException

waitForAll

public boolean waitForAll(Collection collWorkItems,
                          long lTimeoutMillis)
                   throws InterruptedException

Wait for all WorkItems in the collection to finish. If there are no WorkItems in the list then it returns immediately indicating a timeout. WorkItems from different WorkManagers can be placed in a single collection and waited on together.

The WorkItems collection should not be altered once submitted until the method returns.

Specified by:

waitForAll in interface commonj.work.WorkManager

Parameters:

collWorkItems - the Collection of WorkItem objects to wait for

lTimeoutMillis - the timout in milliseconds. If this value is zero then this method returns immediately

Returns:

true if all WorkItems have completed; false if the timeout has expired

Throws:

InterruptedException - thrown if the wait is interrupted

IllegalArgumentException - thrown if workItems is null, any of the objects in the collection are not WorkItems or the timeout is negative

waitForAny

public Collection waitForAny(Collection collWorkItems,
                             long lTimeoutMillis)
                      throws InterruptedException

Wait for any of the WorkItems in the collection to finish. If there are no WorkItems in the list then it returns immediately indicating a timeout. WorkItems from different WorkManagers can be placed in a single collection and waited on together.

The WorkItems collection should not be altered once submitted until the method returns.

Specified by:

waitForAny in interface commonj.work.WorkManager

Parameters:

collWorkItems - the Collection of WorkItem objects to wait for

lTimeoutMillis - the timeout in ms. If this value is zero then the method returns immediately, i.e. does not block

Returns:

the WorkItems that have completed or an empty Collection if its timeout expires before any finished

Throws:

InterruptedException - thrown if the wait is interrupted

IllegalArgumentException - thrown if workItems is null, any of the objects in the collection are not WorkItems or the timeout is negative

getCurrentResult

public WorkManager.WorkStatus getCurrentResult(commonj.work.WorkItem item)

Retrieve a current WorkStatus (partial result) for a given Work.

If the specified work has not been rejected or completed, this method will always communicate with a remote server to retrieve the current WorkStatus.

getService

public InvocationService getService()

Return an InvocationService used by this WorkManager.

Returns:

an InvocationService used by this WorkManager

getServers

public Set getServers()

Return a set of Members that run the same Invocation service as this WorkManager in a "server" capacity.

Returns:

a set of server Members

getPostedWork

public Map getPostedWork()

Return a catalog of WorkHolder objects for all posted Work as known by the client side keyed by the corresponding work id.

getAcceptedWork

public Map getAcceptedWork()

Return a catalog of accepted ScheduleWork tasks as known by the server side keyed by the origin Member where the value is a map of ScheduleWork tasks keyed by the WorkId.

Returns:

a catalog of started ScheduleWork tasks

isServer

public boolean isServer()

Check whether or not this node operates in a "server" mode processing remote Work requests.

Returns:

true if this node operates in a "server" mode processing remote Work requests; false otherwise

disableServer

public void disableServer(Member member)

Remove a Member from a list of active server nodes and terminate all work posted to that server. This method could be called by the client code in response to exceptions (i.e. serialization problems) thrown by a server that deem further use of that server impossible.

cancelPostedWork

public void cancelPostedWork()

Cancel all posted work that has not yet completed.

chooseServer

protected Member chooseServer()

Choose a Member to run a next Work at.

Called by client threads.

getPostedWork

protected WorkManager.WorkHolder getPostedWork(long lWorkId)

Return a WorkHolder for a posted work with a given id.

Parameters:

lWorkId - a work id

Returns:

a WorkHolder for a given work id

removePostedWork

protected WorkManager.WorkHolder removePostedWork(long lWorkId)

Remove a WorkHolder for a posted work with a given id.

Parameters:

lWorkId - a work id

Returns:

a WorkHolder for a given work id

generateWorkId

protected int generateWorkId()

Generate a unique (for this WorkManager) work id.

Called by client threads.

processFeedback

protected void processFeedback(WorkManager.SendFeedback workFeedback)

Process a remote work feedback.

Called by the InvocationService on the service thread at the client VM.

updateWork

protected boolean updateWork(WorkManager.WorkStatus status)

Update a WorkStatus for a work. If the corresponding WorkHolder has already been released, no action takes place.

Called by the InvocationService on a service thread of the client VM.

Parameters:

status - a WorkStatus object with an new status

Returns:

true iff the status was updated; false if the corresponding work has already been released

initWork

protected void initWork(WorkManager.ScheduleWork workAgent)

Initialize the remote work agent.

Called by the InvocationService on the service thread of the server member.

processWork

protected Object processWork(WorkManager.ScheduleWork workAgent)

Run the remote work agent.

Called by a daemon thread of the InvocationService on a server VM.

requestWorkStatus

protected WorkManager.WorkStatus requestWorkStatus(WorkManager.RequestStatus requestAgent)

Obtain current status of the specified Work.

Called by a daemon thread of the InvocationService on a server VM.

releaseWork

protected void releaseWork(WorkManager.ReleaseWork releaseAgent)

Release the remote work agent.

Called by a daemon thread of the InvocationService on a server VM.

main

public static void main(String[] asArg)

Entry point: start a stand-alone WorkManager (server) using the specified name and thread count.

 Example:
   java com.tangosol.coherence.commonj.WorkManager Manager 5