uk.org.ogsadai.activity.transform
Class ZIPArchiveActivity

java.lang.Object
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  +--uk.org.ogsadai.activity.Activity
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        +--uk.org.ogsadai.activity.transform.ZIPArchiveActivity

public class ZIPArchiveActivity

extends Activity

An Activity to archive and compress one or more inputs using the ZIP format. This activity could be used to compress and archive the results of multiple database queries contained in the same perform document. Each activity input will become an entry in the ZIP archive. The activity has two outputs, one is the archived data, the other the ZIP meta-data containing the checksum type and value. For information on this activity see the OGSA-DAI user doc: OGSA-DAI/doc/interaction/activities/transform/zipArchive.html

Author:

The OGSA-DAI Project Team

Field Summary

private static java.lang.String	COPYRIGHT_NOTICE Copyright statement
private IncrementalProcessorInputStream	mArchivedInput Used to read the ZIP archive and drive the processor.
private BlockWriter	mArchivedOutput Activity output - archived data
private byte[]	mBuffer A buffer for temporary storage of blocks.
private java.util.zip.Checksum	mChecksum The checksum type used for the archiving
private BlockWriter	mMetadataOutput Activity output - archive meta data
private ZIPIncrementalProcessor	mProcessor Used to perform the archiving and compression.

Fields inherited from class uk.org.ogsadai.activity.Activity

mContext, mExternalInputs, mExternalOutputs, mInternalInputs, mInternalOutputs

Constructor Summary

ZIPArchiveActivity(org.w3c.dom.Element element)

Method Summary

private java.lang.String	getMetadata() Constructs the activity meta-data XML string.
void	initialise() This method should be overridden by subclasses to perform any initialisation they require before the process method invocations begin.
void	processBlock() Performs an iteration of the processing of an activity.
void	processFirst() This method is called during the first iteration of processing an activity.

Methods inherited from class uk.org.ogsadai.activity.Activity

cleanUp, connectsTo, createOutputPipe, getActivityConfiguration, getActivityName, getCause, getName, getObservableStatus, getProperties, getSession, getStatus, hasActivityConfiguration, hasProperties, process, setActivityName, setCompleted, setError

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

mChecksum

private java.util.zip.Checksum mChecksum

The checksum type used for the archiving

mArchivedOutput

private BlockWriter mArchivedOutput

Activity output - archived data

mMetadataOutput

private BlockWriter mMetadataOutput

Activity output - archive meta data

mProcessor

private final ZIPIncrementalProcessor mProcessor

Used to perform the archiving and compression.

mArchivedInput

private IncrementalProcessorInputStream mArchivedInput

Used to read the ZIP archive and drive the processor.

mBuffer

private byte[] mBuffer

A buffer for temporary storage of blocks.

Constructor Detail

ZIPArchiveActivity

public ZIPArchiveActivity(org.w3c.dom.Element element)
                   throws ActivitySpecificationException,
                          ActivityCreationException

Method Detail

initialise

public void initialise()
                throws ActivitySpecificationException,
                       ActivityExecutionException

Description copied from class: Activity

This method should be overridden by subclasses to perform any initialisation they require before the process method invocations begin. This might be used for setting up convenient fields to reference objects contained in the context. It shouldn't be used for opening resources. That should be done in processFirst.

Overrides:

initialise in class Activity

Throws:

ActivityExecutionException - If some system problem prevents the activity from initialising.

ActivitySpecificationException - If a problem with settings provided by a client prevents the activity from initialising.

processFirst

public void processFirst()

Description copied from class: Activity

This method is called during the first iteration of processing an activity. It can be overridden by subclasses to define some processing that should be done only once during the first iteration of the activity processing, for example evaluating a database query.

Overrides:

processFirst in class Activity

processBlock

public void processBlock()

Description copied from class: Activity

Performs an iteration of the processing of an activity. This may involve reading a block of input data and writing a block of output data, or may involve some other kind of processing. When an activity is processed by the OGSA-DAI engine, this method will be invoked repeatedly until the activity either completes or stops due to an error or termination call. An implementation of this method should invoke the setCompleted method to indicate that processing is complete, or the setError method if an error occurs that will prevent the processing from completing.

Specified by:

processBlock in class Activity

getMetadata

private final java.lang.String getMetadata()

Constructs the activity meta-data XML string.

Returns:

meta data string.