org.jppf.server.protocol

Class JPPFTask

java.lang.Object

org.jppf.server.protocol.JPPFTask

All Implemented Interfaces:

Serializable, Runnable, Task<Object>

Direct Known Subclasses:

CommandLineTask, DemoTask, HelloTask, JPPFAnnotatedTask, JPPFExceptionResult

public abstract class JPPFTask
extends Object
implements Task<Object>

Abstract superclass for all tasks submitted to the execution server. This class provides the basic facilities to handle data shared among tasks, handling of task execution exception, and handling of the execution results.

JPPF clients have to extend this class and must implement the run method. In the run method the task calculations are performed, and the result of the calculations is set with the JPPFTask.setResult(Object) method:

 class MyTask extends JPPFTask {
   public void run() {
     // do the calculation ...
     setResult(myResult);
   }
 }
 

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
JPPFTask() Default constructor.

Method Summary

Methods

Modifier and Type	Method and Description
<V> V	compute(JPPFCallable<V> callable) Compute a value on the client-side, as the result of the execution of a JPPFCallable.
DataProvider	getDataProvider() Get the provider of shared data for this task.
Exception	getException() Get the exception that was raised by this task's execution.
String	getId() Get the user-assigned id for this task.
int	getPosition() Returns the position of this task in the job in which it was submitted.
Object	getResult() Get the result of the task execution.
Object	getTaskObject() Get the JPPFRunnable-annotated object or POJO wrapped by this task.
JPPFSchedule	getTimeoutSchedule() Get the task timeout schedule configuration.
boolean	isInNode() Determine whether this task is executing within a node, or locally on the client side.
void	onCancel() Callback invoked when this task is cancelled.
void	onTimeout() Callback invoked when this task times out.
void	setDataProvider(DataProvider dataProvider) Set the provider of shared data for this task.
void	setException(Exception exception) Sets the exception that was raised by this task's execution in the run method.
void	setId(String id) Set the user-assigned id for this task.
void	setPosition(int position) Set the position of this task in the job in which it was submitted.
void	setResult(Object result) Set the result of the task execution.
void	setTimeoutSchedule(JPPFSchedule timeoutSchedule) Get the task timeout schedule configuration.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.jppf.node.protocol.Task

onRestart

Methods inherited from interface java.lang.Runnable

run

Constructor Detail

JPPFTask

public JPPFTask()

Default constructor.

Method Detail

getResult

public Object getResult()

Description copied from interface: Task

Get the result of the task execution.

Specified by:

getResult in interface Task<Object>

Returns:

the result as an array of bytes.

setResult

public void setResult(Object result)

Description copied from interface: Task

Set the result of the task execution.

Specified by:

setResult in interface Task<Object>

Parameters:

result - the result of this task's execution.

getException

public Exception getException()

Description copied from interface: Task

Get the exception that was raised by this task's execution. If the task raised a Throwable, the exception is embedded into a JPPFException.

Specified by:

getException in interface Task<Object>

Returns:

a Exception instance, or null if no exception was raised.

setException

public void setException(Exception exception)

Description copied from interface: Task

Sets the exception that was raised by this task's execution in the run method. The exception is set by the JPPF framework.

Specified by:

setException in interface Task<Object>

Parameters:

exception - a ClientApplicationException instance.

getDataProvider

public DataProvider getDataProvider()

Description copied from interface: Task

Get the provider of shared data for this task.

Specified by:

getDataProvider in interface Task<Object>

Returns:

a DataProvider instance.

setDataProvider

public void setDataProvider(DataProvider dataProvider)

Description copied from interface: Task

Set the provider of shared data for this task.

Specified by:

setDataProvider in interface Task<Object>

Parameters:

dataProvider - a DataProvider instance.

getPosition

public final int getPosition()

Description copied from interface: Task

Returns the position of this task in the job in which it was submitted.

Specified by:

getPosition in interface Task<Object>

Returns:

the position of this task as an int.

setPosition

public final void setPosition(int position)

Description copied from interface: Task

Set the position of this task in the job in which it was submitted.

Specified by:

setPosition in interface Task<Object>

Parameters:

position - the position of this task as an int.

getId

public String getId()

Description copied from interface: Task

Get the user-assigned id for this task.

Specified by:

getId in interface Task<Object>

Returns:

the id as a string.

setId

public void setId(String id)

Description copied from interface: Task

Set the user-assigned id for this task.

Specified by:

setId in interface Task<Object>

Parameters:

id - the id as a string.

onCancel

public void onCancel()

Description copied from interface: Task

Callback invoked when this task is cancelled. The default implementation does nothing and should be overriden by subclasses that desire to implement a specific behaviour on cancellation.

Specified by:

onCancel in interface Task<Object>

onTimeout

public void onTimeout()

Description copied from interface: Task

Callback invoked when this task times out. The default implementation does nothing and should be overriden by subclasses that desire to implement a specific behaviour on timeout.

Specified by:

onTimeout in interface Task<Object>

getTaskObject

public Object getTaskObject()

Description copied from interface: Task

Get the JPPFRunnable-annotated object or POJO wrapped by this task.

Specified by:

getTaskObject in interface Task<Object>

Returns:

an object or class that is JPPF-annotated.

getTimeoutSchedule

public JPPFSchedule getTimeoutSchedule()

Description copied from interface: Task

Get the task timeout schedule configuration.

Specified by:

getTimeoutSchedule in interface Task<Object>

Returns:

a JPPFSchedule instance.

setTimeoutSchedule

public void setTimeoutSchedule(JPPFSchedule timeoutSchedule)

Description copied from interface: Task

Get the task timeout schedule configuration.

Specified by:

setTimeoutSchedule in interface Task<Object>

Parameters:

timeoutSchedule - a JPPFSchedule instance.

isInNode

public boolean isInNode()

Description copied from interface: Task

Determine whether this task is executing within a node, or locally on the client side.

Specified by:

isInNode in interface Task<Object>

Returns:

true if this task is executing in a node, false if it is on the client side.

compute

public <V> V compute(JPPFCallable<V> callable)
          throws Exception

Description copied from interface: Task

Compute a value on the client-side, as the result of the execution of a JPPFCallable.

Any Throwable raised in the callable's call() method will be thrown as the result of this method. If the Throwable is an instance of Exception or one of its subclasses, it is thrown as such, otherwise it is wrapped into a JPPFException.

Specified by:

compute in interface Task<Object>

Type Parameters:

V - the type of results returned by the callable.

Parameters:

callable - the callable to execute on the client side.

Returns:

the value computed on the client, or null if the value could not be computed.

Throws:

Exception - if the execution of the callable in the client resulted in a Throwable being raised.

See Also:

JPPFCallable