uk.org.ogsadai.engine
Class ProcessingStatus

java.lang.Object
  |
  +--java.util.Observable
        |
        +--uk.org.ogsadai.engine.ProcessingStatus

public class ProcessingStatus

extends java.util.Observable

An Observable class encapsulating the state of processing of OGSA-DAI entities, such as Request or Activity objects.

Instances of this class are implemented as Observable wrappers around a ProcessingStatus field. Observer implementations can be registered and they will each be updated every time the status is changed using the setXYZ methods.

Each instance of this class is regarded as being "owned" by the object for which it acts as status. This "owner" object, which may not be 'null', is made known to the instance at construction time. A reference to the owner object is then subsequently passed to observers as the second argument of their update() method.

A rich set of predicates is provided to establish:

• the current state at any time
• properties of the owner object implied by the current state; e.g., whether it is live or has ceased processing)

The present implementation uses synchronised methods for thread-safety.

Author:

The OGSA-DAI Project Team

Field Summary

private static java.lang.String	COPYRIGHT_NOTICE Copyright statement
private java.lang.Object	mOwner Object whose status is provided by this instance.
private ProcessingState	mState Current state.

Fields inherited from class java.util.Observable

Constructor Summary

ProcessingStatus(java.lang.Object owner)
Constructs an instance of this class using a given owner object.

ProcessingStatus(java.lang.Object owner, ProcessingState initialState)
Constructs an instance of this class using a given owner object and initial state.

Method Summary

void	copyState(ProcessingStatus status) Copies the state of the specified ProcessingStatus object to that of this ProcessingStatus object.
boolean	isActive() Indicates whether the owner object is being initialised or processed.
boolean	isCompleted() Indicates whether processing has completed on the owner object.
boolean	isError() Indicates whether the owner object has stopped processing due to errors.
boolean	isInitialising() Indicates whether initialisation is being carried out on the object for which this instance acts as status.
boolean	isLive() Indicates whether the owner object is still processing or pending initialisation.
boolean	isProcessing() Indicates whether initialisation is complete and processing has commenced.
boolean	isStopped() Indicates whether all processing has stopped on the owner object.
boolean	isTerminated() Indicates whether the processing of the owner object has been externally terminated.
boolean	isTimedOut() Indicates whether processing of the owner object has timed out.
boolean	isUnstarted() Indicates whether the owner object remains uninitialised.
void	setCompleted() Updates the status to reflect that the onwer object has completed processing.
void	setError() Updates the status to reflect that the initialisation or processing of the onwer object has yielded errors.
void	setInitialising() Updates the status to reflect that the onwer object is being initialised.
void	setProcessing() Updates the status to reflect that the onwer object is being actively processed.
private void	setState(ProcessingState nextState) Effects an internal change of state.
void	setTerminated() Updates the status to reflect that the onwer object has been terminated.
void	setTimedOut() Updates the status to reflect that the onwer object has been timed out.
java.lang.String	toString() Provides a textual rendition of the current state.

Methods inherited from class java.util.Observable

addObserver, clearChanged, countObservers, deleteObserver, deleteObservers, hasChanged, notifyObservers, notifyObservers, setChanged

Methods inherited from class java.lang.Object

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

Field Detail

COPYRIGHT_NOTICE

private static final java.lang.String COPYRIGHT_NOTICE

Copyright statement

See Also:

Constant Field Values

mState

private ProcessingState mState

Current state.

mOwner

private java.lang.Object mOwner

Object whose status is provided by this instance.

Constructor Detail

ProcessingStatus

public ProcessingStatus(java.lang.Object owner,
                        ProcessingState initialState)
                 throws java.lang.IllegalArgumentException

Constructs an instance of this class using a given owner object and initial state.

Parameters:

owner - the object for which the new instance acts as status

initialState - the state with which to initialise the new instance

Throws:

java.lang.IllegalArgumentException - if either of the two parameters is null

ProcessingStatus

public ProcessingStatus(java.lang.Object owner)
                 throws java.lang.IllegalArgumentException

Constructs an instance of this class using a given owner object. The instance produced reflects an initial state of ProcessingState.UNSTARTED.

Parameters:

owner - the object for which the new instance acts as status

Throws:

java.lang.IllegalArgumentException - if the supplied argument is null

Method Detail

setState

private void setState(ProcessingState nextState)

Effects an internal change of state.

Parameters:

nextState - the target state to which a transition is made.

isStopped

public boolean isStopped()

Indicates whether all processing has stopped on the owner object.

Returns:

true if processing has stopped, either normally or as a result of errors, termination or timing out; false otherwise.

isLive

public boolean isLive()

Indicates whether the owner object is still processing or pending initialisation.

Returns:

true if processing is as yet unstarted or ongoing; false otherwise.

isActive

public boolean isActive()

Indicates whether the owner object is being initialised or processed.

Returns:

true if processing is ongoing (i.e., the processing entity is initialising or being processed); false otherwise.

isCompleted

public final boolean isCompleted()

Indicates whether processing has completed on the owner object.

Returns:

true if and only if the current state is ProcessingState.COMPLETED.

isError

public final boolean isError()

Indicates whether the owner object has stopped processing due to errors.

Returns:

true if and only if the current state is ProcessingState.ERROR.

isTimedOut

public final boolean isTimedOut()

Indicates whether processing of the owner object has timed out.

Returns:

true if and only if the current state is ProcessingState.TIMEDOUT.

isUnstarted

public final boolean isUnstarted()

Indicates whether the owner object remains uninitialised.

Returns:

true if and only if the current state is ProcessingState.UNSTARTED.

isInitialising

public final boolean isInitialising()

Indicates whether initialisation is being carried out on the object for which this instance acts as status.

Returns:

true if and only if the current state is ProcessingState.INITIALISING.

isProcessing

public final boolean isProcessing()

Indicates whether initialisation is complete and processing has commenced.

Returns:

true if and only if the current state is ProcessingState.PROCESSING.

isTerminated

public final boolean isTerminated()

Indicates whether the processing of the owner object has been externally terminated.

Returns:

true if and only if the current state is ProcessingState.TERMINATED.

setInitialising

public void setInitialising()
                     throws java.lang.IllegalStateException

Updates the status to reflect that the onwer object is being initialised.

Throws:

java.lang.IllegalStateException - if the current status indicates that initialisation has already commenced or completed.

setProcessing

public void setProcessing()
                   throws java.lang.IllegalStateException

Updates the status to reflect that the onwer object is being actively processed.

Throws:

java.lang.IllegalStateException - if the current status indicates that processing has already commenced or completed.

setCompleted

public void setCompleted()
                  throws java.lang.IllegalStateException

Updates the status to reflect that the onwer object has completed processing.

Throws:

java.lang.IllegalStateException - if the current status indicates that processing has already completed, either normally or otherwise.

setError

public void setError()
              throws java.lang.IllegalStateException

Updates the status to reflect that the initialisation or processing of the onwer object has yielded errors.

Throws:

java.lang.IllegalStateException - if the current status indicates that the owner object is already inactive.

setTerminated

public void setTerminated()
                   throws java.lang.IllegalStateException

Updates the status to reflect that the onwer object has been terminated.

Throws:

java.lang.IllegalStateException - if the current status indicates that all activity on the owner object has already stopped, either normally or otherwise.

setTimedOut

public void setTimedOut()

Updates the status to reflect that the onwer object has been timed out.

Throws:

java.lang.IllegalStateException - if the current status indicates that all activity on the owner object has already stopped, either normally or otherwise.

toString

public java.lang.String toString()

Provides a textual rendition of the current state.

Overrides:

toString in class java.lang.Object

Returns:

a String object encoding the current state, e.g., "INITIALISING" or "TIMEDOUT".

See Also:

ProcessingState

copyState

public void copyState(ProcessingStatus status)

Copies the state of the specified ProcessingStatus object to that of this ProcessingStatus object.

Parameters:

status - the status to copy