uk.org.ogsadai.activity.relational
Class PhysicalSchemaFileActivity

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

All Implemented Interfaces:

ActivityConfigurationCreator

public class PhysicalSchemaFileActivity

extends Activity

implements ActivityConfigurationCreator

An activity that retrieves physical metadata from a file (stored in the configuration for this activity) and writes it as an XML string to its only output. This activity does not communicate with any data resource.

Author:

The OGSA-DAI Team.

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

mConfig

private PhysicalSchemaFileActivityConfiguration mConfig

the configuration document

mTableName

private java.lang.String mTableName

Name of the table for which to retrieve metadata (or null if metadata is being retrieved for all tables)

mTables

private java.util.Iterator mTables

Iterates through all table names in the config document

mOutput

private BlockWriter mOutput

Activity output - physical metadata

PhysicalSchemaFileActivity

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

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

createActivityConfiguration

public ActivityConfiguration createActivityConfiguration()

Description copied from interface: ActivityConfigurationCreator

Creates the ActivityConfiguration object for a particular activity. The intialise method of the ActivityConfiguration object will be invoked by an ActivityCreator.

Specified by:

createActivityConfiguration in interface ActivityConfigurationCreator

Returns:

an ActivityConfiguration object

writeTable

private void writeTable(java.lang.String name,
                        java.lang.StringBuffer schema)

Writes a table description to the input string buffer.

Parameters:

name - Name of the table.

schema - String buffer to write description to.