uk.org.ogsadai.activity.transform
Class WebRowSetProjectionActivity

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

public class WebRowSetProjectionActivity

extends Activity

A WebRowSetProjectionActivity projects a WebRowSet input document onto a column name or a column index.

For information on this activity see the OGSA-DAI user doc: OGSA-DAI/doc/interaction/activities/transform/webrowsetProjection.html

Author:

The OGSA-DAI Project Team.

Field Summary

private static java.lang.String	COPYRIGHT_NOTICE Copyright notice
private javax.xml.parsers.DocumentBuilderFactory	dbf The document builder factory to parse the WebRowSet document
private int	index The index of the column name
private boolean	isFirstBlock Check if it is the first block
private int	mAttributeIndex The index of the attribute
private java.lang.String	mAttributeName The name of the attribute
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

WebRowSetProjectionActivity(org.w3c.dom.Element element)
Constructs an activity using the specified element.

Method Summary

private int	handleFirstBlock(java.lang.Object inputBlock, javax.xml.parsers.DocumentBuilder db) Handles the first block of the activity and determines index of requested column from the column name (in the case where the client provided the name of the column and not the index).
private void	handleRestBlocks(java.lang.Object inputBlock, javax.xml.parsers.DocumentBuilder db) Handles the remaining blocks that arrive.
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.

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

mInput

private BlockReader mInput

Activity input.

mOutput

private BlockWriter mOutput

Activity output.

mAttributeName

private java.lang.String mAttributeName

The name of the attribute

mAttributeIndex

private int mAttributeIndex

The index of the attribute

isFirstBlock

private boolean isFirstBlock

Check if it is the first block

index

private int index

The index of the column name

dbf

private javax.xml.parsers.DocumentBuilderFactory dbf

The document builder factory to parse the WebRowSet document

Constructor Detail

WebRowSetProjectionActivity

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

Constructs an activity using the specified element.

Parameters:

element - Element to configure the activity with - from a perform document.

Throws:

ActivityCreationException - If there is a problem constructing the activity.

ActivitySpecificationException - If there is a problem constructing the activity due to an invalid setting in element.

See Also:

uk.org.ogsadai.activity

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.

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

handleFirstBlock

private int handleFirstBlock(java.lang.Object inputBlock,
                             javax.xml.parsers.DocumentBuilder db)
                      throws ActivitySpecificationException,
                             ActivityExecutionException

Handles the first block of the activity and determines index of requested column from the column name (in the case where the client provided the name of the column and not the index).

Parameters:

inputBlock - First input block received.

db - XML document builder in which WebRowSet document is constructed.

Returns:

index of requested column.

Throws:

ActivitySpecificationException - If the input is not a WebRowSet or if the the column requested by the client does not exist in the WebRowSet.

ActivityExecutionException - If some internal parsing problem arises.

handleRestBlocks

private void handleRestBlocks(java.lang.Object inputBlock,
                              javax.xml.parsers.DocumentBuilder db)
                       throws ActivitySpecificationException,
                              ActivityExecutionException

Handles the remaining blocks that arrive.

Parameters:

inputBlock - First input block received.

db - XML document builder in which WebRowSet document is constructed.

Throws:

ActivitySpecificationException - If the input is not a WebRowSet or if the the column requested by the client does not exist in the WebRowSet.

ActivityExecutionException - If some internal parsing problem arises.