uk.org.ogsadai.activity
Class ActivityRequest

java.lang.Object
  |
  +--uk.org.ogsadai.activity.ActivityRequest

All Implemented Interfaces:

Request, SessionParticipant

public class ActivityRequest

extends java.lang.Object

implements Request, SessionParticipant

Implementation of interface Request that encapsulates all of the objects required to create, process and obtain responses from a single request. It also encapsulates the state-machine logic used to track down the processing status of the request.

Author:

The OGSA-DAI Project Team

Nested Class Summary

private class

ActivityRequest.TimeOutTask Auxialliary timer task class associated with the timeout timer

Field Summary

private static java.lang.String	COPYRIGHT_NOTICE Copyright statement.
private static DAILogger	LOG Logger object for this request.
private ActivityContext	mActivityContext Activity context for the activities in the request.
private EngineConfiguration	mConfiguration Engine configuration information.
private ProcessingStatusObserver	mObserver Observer object for detecting completion
private RequestComponent	mRequest References the top-level component of the composite object representing a single request.
private RequestContext	mRequestContext Context for this request.
private ResponseBuilder	mResponseBuilder Response builder used for assembling the response to the request.
private Session	mSession The session that the request has joined.
private ProcessingStatus	mStatus The observable status for this request.
private SessionStrategy	mStrategy The session access strategy for the request.
private java.lang.Thread	mThread Thread used for processing this request.
private java.util.Timer	mTimeOutTimer The timer object responsible for effectinbg time-outs.

Constructor Summary

ActivityRequest(RequestComponent composite, SessionStrategy strategy)
Constructs an instance associated with a specific request component and session strategy.

Method Summary

private void	endProcessing() Ends the processing of this request, leaving the status unaffected.
(package private) RequestComponent	getRequestComposite() Returns the composite RequestComponent for the request.
Session	getSession() Gets the Session that the session participant is joined to.
SessionStrategy	getSessionStrategy() Gets the SessionStrategy object for the session participant.
ProcessingStatus	getStatus() Returns the processing status of this request.
void	initialise(EngineConfiguration config, RequestContext context, ResponseBuilder builder) Initialises this request before its processing can commence.
void	process() Initiates the processing of the request.
private void	processAsynchronously() Spawn a processing thread and process the request asynchronously.
private void	reportError(java.lang.Exception cause) This is invoked when an error occurs while processing the request.
void	setSession(Session session) Provides the session participant with the session to which it is joined.
void	terminate() Terminates the request.
void	waitForResponse() Waits for the response building to complete.

Methods inherited from class java.lang.Object

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

Field Detail

COPYRIGHT_NOTICE

private static final java.lang.String COPYRIGHT_NOTICE

Copyright statement.

See Also:

Constant Field Values

LOG

private static final DAILogger LOG

Logger object for this request.

mRequest

private RequestComponent mRequest

References the top-level component of the composite object representing a single request.

mThread

private java.lang.Thread mThread

Thread used for processing this request.

mStatus

private final ProcessingStatus mStatus

The observable status for this request.

mStrategy

private SessionStrategy mStrategy

The session access strategy for the request.

mSession

private Session mSession

The session that the request has joined.

mRequestContext

private RequestContext mRequestContext

Context for this request.

mActivityContext

private ActivityContext mActivityContext

Activity context for the activities in the request.

mResponseBuilder

private ResponseBuilder mResponseBuilder

Response builder used for assembling the response to the request.

mConfiguration

private EngineConfiguration mConfiguration

Engine configuration information.

mObserver

private ProcessingStatusObserver mObserver

Observer object for detecting completion

mTimeOutTimer

private java.util.Timer mTimeOutTimer

The timer object responsible for effectinbg time-outs. Set to null if timeouts aren't used.

Constructor Detail

ActivityRequest

public ActivityRequest(RequestComponent composite,
                       SessionStrategy strategy)

Constructs an instance associated with a specific request component and session strategy.

Parameters:

composite - Request component.

strategy - Session strategy.

Method Detail

getStatus

public ProcessingStatus getStatus()

Returns the processing status of this request.

Specified by:

getStatus in interface Request

Returns:

the current processing status as a Status object.

initialise

public void initialise(EngineConfiguration config,
                       RequestContext context,
                       ResponseBuilder builder)
                throws java.lang.IllegalStateException,
                       RequestSpecificationException,
                       RequestExecutionException

Description copied from interface: Request

Initialises this request before its processing can commence.

Initialisation may be performed once only, prior to invoking any of the other methods on the Request interface.

Specified by:

initialise in interface Request

Throws:

java.lang.IllegalStateException - If invoked after the processing of the request has been initiated or terminated.

RequestExecutionException - if the request fails to execute due to a problem in the e.g. a database connection disappears or a file is corrupted.

RequestSpecificationException - if the request fails to execute due to a problem in the request e.g. it specifies an unsupported activity or a query expression is has incorrect syntax.

process

public void process()
             throws java.lang.IllegalStateException

Description copied from interface: Request

Initiates the processing of the request. After this method returns the response will be available via the ResponseBuilder passed into the process method.

All implementations of this method must ensure that processing is a non-blocking operation; e.g., by delegating the actual processing to a separate thread. This method should return as soon as processing is suitably initiated and should not wait until processing completes.

Specified by:

process in interface Request

Throws:

java.lang.IllegalStateException - if invoked before the request has been initialised, or after processing has commenced, completed or terminated.

terminate

public void terminate()

Description copied from interface: Request

Terminates the request. When this method returns, any threads and other resources associated with the request must be finished with.

Specified by:

terminate in interface Request

endProcessing

private void endProcessing()

Ends the processing of this request, leaving the status unaffected.

waitForResponse

public void waitForResponse()

Description copied from interface: Request

Waits for the response building to complete. After this method returns, the response product can be retrieved from the ResponseBuilder. This may or may not indicate that the request processing is complete, depending on the type of request. For example some requests produce no response data, so the response may be available before processing completes.

Specified by:

waitForResponse in interface Request

reportError

private final void reportError(java.lang.Exception cause)

This is invoked when an error occurs while processing the request.

Parameters:

cause - The cause of the error

processAsynchronously

private void processAsynchronously()

Spawn a processing thread and process the request asynchronously.

getSessionStrategy

public SessionStrategy getSessionStrategy()

Description copied from interface: SessionParticipant

Gets the SessionStrategy object for the session participant.

This object understands how to obtain the session from the SessionManager for this session participant.

Specified by:

getSessionStrategy in interface SessionParticipant

Returns:

SessionStrategy object.

setSession

public void setSession(Session session)

Description copied from interface: SessionParticipant

Provides the session participant with the session to which it is joined. After this method has been invoked, the session participant may access and interact with the session via the getSession() method.

Specified by:

setSession in interface SessionParticipant

Parameters:

session - The Session for the participant to join.

getSession

public Session getSession()

Description copied from interface: SessionParticipant

Gets the Session that the session participant is joined to.

This can only be invoked after the setSession() method has been invoked.

Specified by:

getSession in interface SessionParticipant

Returns:

session associated with this session participant

getRequestComposite

RequestComponent getRequestComposite()

Returns the composite RequestComponent for the request. This accessor method provided for testing purposes.

Returns:

ResourceComponent