uk.org.ogsadai.activity.xmldb
Class XMLDBActivity

java.lang.Object
  |
  +--uk.org.ogsadai.activity.Activity
        |
        +--uk.org.ogsadai.activity.xmldb.XMLDBActivity

Direct Known Subclasses:

XMLBulkLoadActivity, XMLDBCommandActivity, XPathStatementActivity, XQueryStatementActivity, XUpdateStatementActivity

public abstract class XMLDBActivity

extends Activity

This is the base class for all Activity implementations that interact with XMLDB data service resources/

Author:

The OGSA-DAI Project Team

Field Summary

private static java.lang.String	COPYRIGHT_NOTICE Copyright statement
private static DAILogger	LOG Logger object for logging in this class
protected XMLDBCollectionProvider	mDataResource Used to access the XMLDB Collection.
protected BlockWriter	mOutput Activity output used for all XMLDB Activities.
protected java.lang.String	mSubCollectionName The sub-collection that the activity is operation on.
protected java.lang.String	mUserCredentials User credentials for accessing the data resource.

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

mContext, mExternalInputs, mExternalOutputs, mInternalInputs, mInternalOutputs

Constructor Summary

XMLDBActivity(org.w3c.dom.Element element)
Constructs an XMLDB activity using the specified XML element.

Method Summary

void	initialise() This method should be overridden by subclasses to perform any initialisation they require before the process method invocations begin.
abstract 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 statement

See Also:

Constant Field Values

LOG

private static final DAILogger LOG

Logger object for logging in this class

mOutput

protected BlockWriter mOutput

Activity output used for all XMLDB Activities.

mDataResource

protected XMLDBCollectionProvider mDataResource

Used to access the XMLDB Collection.

mUserCredentials

protected java.lang.String mUserCredentials

User credentials for accessing the data resource.

mSubCollectionName

protected java.lang.String mSubCollectionName

The sub-collection that the activity is operation on. If this is null then the activity is operating on the data resource's base collection.

Constructor Detail

XMLDBActivity

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

Constructs an XMLDB activity using the specified XML element.

Parameters:

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

Throws:

ActivityCreationException - If there is a problem constructing the activity due to an implementation error or OGSA-DAI confguration problem.

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

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 abstract 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