com.whitestein.lsps.engine

Class AbstractAsynchronousExecutionTask

java.lang.Object

com.whitestein.lsps.engine.AbstractAsynchronousExecutionTask

All Implemented Interfaces:

AsynchronousExecutionTask, ExecutableTask

Direct Known Subclasses:

HttpClientTask, WsSoapCall

@PermitAll
public abstract class AbstractAsynchronousExecutionTask
extends Object
implements AsynchronousExecutionTask

This is the base class for all tasks, which needs to perform some heavy computing or any other long running operations. This task encapsulates logic of asynchronous execution of code. When the task is started, data needed for execution are collected (collectDataForExecution(TaskContext)) and then the message is sent to queue. Upon message retrieval, ProcessAgentMDB will invoke method processDataAsynchronously(java.io.Serializable). Since this invocation is done outside of model instance execution, this doesn't block transaction or model instance execution or any other process-related resources. After the execution finish, the resulting data are sent back to task, so that the task can process it in the model instance context (processExecutionResult(com.whitestein.lsps.engine.lang.TaskContext, java.io.Serializable)). Since sometimes can be useful to execute task synchronously or asynchronously based on task context (metadata, parameters etc.), this task also defines method executeAsynchronously(TaskContext) which determines if the execution is performed directly in model instance context or asynchronously.

Author:

mbj

Nested Class Summary

Nested classes/interfaces inherited from interface com.whitestein.lsps.engine.ExecutableTask

ExecutableTask.Result

Constructor Summary

Constructors

Constructor and Description
AbstractAsynchronousExecutionTask()

Method Summary

Modifier and Type	Method and Description
abstract Serializable	collectDataForExecution(TaskContext context) Collects data from task context for asynchronous execution.
abstract boolean	executeAsynchronously(TaskContext context) Determines, based on current task context (params, metadata, etc.) if the exeuction should be done asynchronously.
abstract Class<? extends AbstractAsynchronousExecutionTask>	getImplementationClass()
abstract Serializable	processDataAsynchronously(Serializable data) Process data collected in AsynchronousExecutionTask.collectDataForExecution(com.whitestein.lsps.engine.lang.TaskContext).
abstract void	processExecutionResult(TaskContext context, Serializable result) This method is called after the asynchronous execution has been done
ExecutableTask.Result	processInput(TaskContext context, Object input) The method for processing the model instance input.
ExecutableTask.Result	start(TaskContext context) An initial method that is called when the task execution starts.
void	terminate(TaskContext context, TerminationReason reason) Called when this task is to be terminated.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractAsynchronousExecutionTask

public AbstractAsynchronousExecutionTask()

Method Detail

start

public ExecutableTask.Result start(TaskContext context)
                            throws ErrorException

Description copied from interface: ExecutableTask

An initial method that is called when the task execution starts.

Specified by:

start in interface ExecutableTask

Returns:

result of execution, must not be null

Throws:

ErrorException - the BPMN error

getImplementationClass

public abstract Class<? extends AbstractAsynchronousExecutionTask> getImplementationClass()

Returns:

class of implementation. We can't use plain this.getClass() since weblogic returns the class of some weblogic specific subclass (some wrapper) and we need concrete implementation in order to look it up from ComponentService.

processInput

public ExecutableTask.Result processInput(TaskContext context,
                                          Object input)
                                   throws ErrorException

Description copied from interface: ExecutableTask

The method for processing the model instance input.

This method is invoked when a previous call to either start method or processInput method returned WAITING_FOR_INPUT and a new input is to be process by the model instance.

Specified by:

processInput in interface ExecutableTask

Returns:

result of execution, must not be null

Throws:

ErrorException - the BPMN error

terminate

public void terminate(TaskContext context,
                      TerminationReason reason)

Description copied from interface: ExecutableTask

Called when this task is to be terminated. This method is called also in case of normal task completion.

Specified by:

terminate in interface ExecutableTask

See Also:

ErrorException

collectDataForExecution

public abstract Serializable collectDataForExecution(TaskContext context)
                                              throws ErrorException

Description copied from interface: AsynchronousExecutionTask

Collects data from task context for asynchronous execution. These data will be used to invoke AsynchronousExecutionTask.processDataAsynchronously(java.io.Serializable) method asynchronously.

Specified by:

collectDataForExecution in interface AsynchronousExecutionTask

Returns:

data that will be used in asynchronous execution

Throws:

ErrorException

processExecutionResult

public abstract void processExecutionResult(TaskContext context,
                                            Serializable result)
                                     throws ErrorException

Description copied from interface: AsynchronousExecutionTask

This method is called after the asynchronous execution has been done

Specified by:

processExecutionResult in interface AsynchronousExecutionTask

result - result of asynchronous call of method AsynchronousExecutionTask.processDataAsynchronously(java.io.Serializable)

Throws:

ErrorException

processDataAsynchronously

public abstract Serializable processDataAsynchronously(Serializable data)

Description copied from interface: AsynchronousExecutionTask

Process data collected in AsynchronousExecutionTask.collectDataForExecution(com.whitestein.lsps.engine.lang.TaskContext). This execution is done asynchronously outside of process model. The result of this execution is afterwards sent back to task (AsynchronousExecutionTask.processExecutionResult(com.whitestein.lsps.engine.lang.TaskContext, java.io.Serializable)) so that the computed results can be processed and any necessary changes in model instance can be done. This method should not throw ErrorException since it is not executed in model instance context.

Specified by:

processDataAsynchronously in interface AsynchronousExecutionTask

Parameters:

data - data to process

Returns:

result of execution

executeAsynchronously

public abstract boolean executeAsynchronously(TaskContext context)
                                       throws ErrorException

Description copied from interface: AsynchronousExecutionTask

Determines, based on current task context (params, metadata, etc.) if the exeuction should be done asynchronously. If true, method AsynchronousExecutionTask.processDataAsynchronously(java.io.Serializable) will be executed outside model instance (thus not blocking transaction, model execution, etc.}. If false it will be called directly.

Specified by:

executeAsynchronously in interface AsynchronousExecutionTask

Returns:

true if the execution should be performed asynchronously, false otherwise

Throws:

ErrorException