uk.org.ogsadai.activity.sql
Class SQLBagActivity

java.lang.Object
  |
  +--uk.org.ogsadai.activity.Activity
        |
        +--uk.org.ogsadai.activity.sql.SQLQueryMultipleActivity
              |
              +--uk.org.ogsadai.activity.sql.SQLBagActivity

public class SQLBagActivity

extends SQLQueryMultipleActivity

This activity runs queries over two relational data service resources and merges the results into a single WebRowSet document and sends it back as the output of this activity.

Each one of the above data service resources is linked to the multiple data service resource implemented by the SQLMultipleDataResource accessor.

The activity's perform document is defined by schema/ogsadai/xsd/activities/sql_bag.xsd.

The activity calls multiple data service resources each one being executed in its own thread.

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

Author:

The OGSA-DAI Project Team.

Field Summary

static java.lang.String	ACTIVITY_OUTPUT Constant used to parse request - activity element
private static java.lang.String	COPYRIGHT_NOTICE Copyright statement
private static DAILogger	LOG Logger object for this activity
private org.w3c.dom.Element	mActivityElement XML element containing activity information from request
private boolean	mIsAllNull Check whether all the returned results are null
private boolean	mIsError Check whether an error has occured or not
private java.lang.Throwable	mThrowable Exception to be forwarded if there is an error and there are no results returned.
static java.lang.String	SQL_STATEMENT Constant used to parse request - SQL query statement element
static java.lang.String	TIMEOUT Constant used to parse request - timeout

Fields inherited from class uk.org.ogsadai.activity.sql.SQLQueryMultipleActivity

mClientTimeout, mMultipleDS, mOutput, mOutputString, mSqlStatement, mTimeoutStatus, mTimer

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

mContext, mExternalInputs, mExternalOutputs, mInternalInputs, mInternalOutputs

Constructor Summary

SQLBagActivity(org.w3c.dom.Element element)

Method Summary

private java.lang.String	mergeResults(java.lang.String[] rowsets) Merge N WebRowSets.
void	processBlock() Performs an iteration of the processing of an activity.

Methods inherited from class uk.org.ogsadai.activity.sql.SQLQueryMultipleActivity

cleanUp, initialise, isTimeout, setTimeout

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

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 this activity

mActivityElement

private org.w3c.dom.Element mActivityElement

XML element containing activity information from request

mIsError

private boolean mIsError

Check whether an error has occured or not

mIsAllNull

private boolean mIsAllNull

Check whether all the returned results are null

mThrowable

private java.lang.Throwable mThrowable

Exception to be forwarded if there is an error and there are no results returned.

ACTIVITY_OUTPUT

public static final java.lang.String ACTIVITY_OUTPUT

Constant used to parse request - activity element

See Also:

Constant Field Values

SQL_STATEMENT

public static final java.lang.String SQL_STATEMENT

Constant used to parse request - SQL query statement element

See Also:

Constant Field Values

TIMEOUT

public static final java.lang.String TIMEOUT

Constant used to parse request - timeout

See Also:

Constant Field Values

Constructor Detail

SQLBagActivity

public SQLBagActivity(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

mergeResults

private java.lang.String mergeResults(java.lang.String[] rowsets)
                               throws XMLDocumentException,
                                      XMLParseException

Merge N WebRowSets.

Parameters:

rowsets - N WebRowSet documents

Returns:

merged WebRowSet result as a string or null if there are no documents.

Throws:

XMLDocumentException - If any of the documents are not valid XML

XMLParseException - If an internal parsing exception occurs