uk.org.ogsadai.activity.relational
Class DatabaseSchemaToXMLActivity

java.lang.Object
  |
  +--uk.org.ogsadai.activity.Activity
        |
        +--uk.org.ogsadai.activity.relational.DatabaseSchemaToXMLActivity

public class DatabaseSchemaToXMLActivity

extends Activity

An activity that converts a stream of table metadata objects into an XML document.

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

Author:

The OGSA-DAI Team.

Field Summary

private static java.lang.String	COPYRIGHT_NOTICE Copyright statement
private static DAILogger	LOG Logger object for logging in this class
private SchemaConverter	mConverter Converter used to convert from database metadata to XML
private BlockReader	mInput Activity's only input - database metadata
private BlockWriter	mOutput Activity's only output - an XML document

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

mContext, mExternalInputs, mExternalOutputs, mInternalInputs, mInternalOutputs

Constructor Summary

DatabaseSchemaToXMLActivity(org.w3c.dom.Element element)

Method Summary

protected void	cleanUp() This method can be overridden by any Activity implementations that need to free up resources in the event of an error or intermediate termination of the activity processing.
void	initialise() This method should be overridden by subclasses to perform any initialisation they require before the process method invocations begin.
protected void	processBlock() Performs an iteration of the processing of an activity.
protected void	processFirst() This method is called during the first iteration of processing an activity.

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

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

LOG

private static DAILogger LOG

Logger object for logging in this class

mInput

private BlockReader mInput

Activity's only input - database metadata

mOutput

private BlockWriter mOutput

Activity's only output - an XML document

mConverter

private SchemaConverter mConverter

Converter used to convert from database metadata to XML

Constructor Detail

DatabaseSchemaToXMLActivity

public DatabaseSchemaToXMLActivity(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

protected 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

protected 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

cleanUp

protected void cleanUp()

Description copied from class: Activity

This method can be overridden by any Activity implementations that need to free up resources in the event of an error or intermediate termination of the activity processing.

Overrides:

cleanUp in class Activity