uk.org.ogsadai.activity.transform
Class BlockAggregatorActivity

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

public class BlockAggregatorActivity

extends Activity

This activity aggregates blocks together using overloaded processBlocks(Type) methods. Currently has methods for both String and Node types, but only String types are enabled. The method for aggregating Node's is currently untested. For information on this activity see the OGSA-DAI user doc: OGSA-DAI/doc/interaction/activities/transform/blockAggregator.html

Author:

The OGSA-DAI Project Team

Field Summary

private static java.lang.String	COPYRIGHT_NOTICE Copyright notice
private static DAILogger	LOG Logger object for logging in this class
private int	mBlockSize Number of blocks to aggregate at a size (size of aggregated block)
private BlockReader	mInput Activity input
private BlockWriter	mOutput Activity output

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

mContext, mExternalInputs, mExternalOutputs, mInternalInputs, mInternalOutputs

Constructor Summary

BlockAggregatorActivity(org.w3c.dom.Element element)

Method Summary

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.
protected java.lang.Object	processBlocks(org.w3c.dom.Node node) Aggregates org.w3c.dom objects.
protected java.lang.Object	processBlocks(java.lang.String string) Aggregates Strings.

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

cleanUp, connectsTo, createOutputPipe, getActivityConfiguration, getActivityName, getCause, getName, getObservableStatus, getProperties, getSession, getStatus, hasActivityConfiguration, hasProperties, process, processFirst, 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 notice

See Also:

Constant Field Values

LOG

private static DAILogger LOG

Logger object for logging in this class

mInput

private BlockReader mInput

Activity input

mOutput

private BlockWriter mOutput

Activity output

mBlockSize

private int mBlockSize

Number of blocks to aggregate at a size (size of aggregated block)

Constructor Detail

BlockAggregatorActivity

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

Method Detail

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

processBlocks

protected java.lang.Object processBlocks(java.lang.String string)
                                  throws ActivitySpecificationException

Aggregates Strings.

Parameters:

string - Initial string.

Returns:

the aggregated strings as a String.

Throws:

ActivitySpecificationException - If a problem is encountered when aggregating the nodes due to a non-String block arriving.

processBlocks

protected java.lang.Object processBlocks(org.w3c.dom.Node node)
                                  throws ActivitySpecificationException

Aggregates org.w3c.dom objects. This can handle Elements, Nodes and DocumentFragments

Parameters:

node - Node to aggregate additional objects to.

Returns:

the nodes aggregated into a DocumentFragment node.

Throws:

ActivitySpecificationException - If a problem is encountered when aggregating the nodes due to a non-Node block arriving.

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.