RandomSampleActivity (OGSA-DAI -- (c) International Business Machines Corporation, 2002-2006, The University of Edinburgh, 2002-2006)

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uk.org.ogsadai.activity.transform
Class RandomSampleActivity

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

public class RandomSampleActivity
extends Activity

A RandomSampleActivity takes as input a sequence of values and returns a random subset of them basen on the fraction provided. Optionally, seed can also be provided.

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

Author:: The OGSA-DAI Project Team

Field Summary
`private static java.lang.String`	`COPYRIGHT_NOTICE` Copyright
`private float`	`fraction` the fraction
`private boolean`	`is_seed` checks if the seed exists
`private BlockReader`	`mInput` Activity input.
`private BlockWriter`	`mOutput` Activity output.
`private java.util.Random`	`ra` the random generator
`private long`	`seed` the seed

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

mContext, mExternalInputs, mExternalOutputs, mInternalInputs, mInternalOutputs

Constructor Summary
`RandomSampleActivity(org.w3c.dom.Element element)`

Method Summary
`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

See Also:: Constant Field Values

mInput

private BlockReader mInput

Activity input.

mOutput

private BlockWriter mOutput

Activity output.

fraction

private float fraction

the fraction

is_seed

private boolean is_seed

checks if the seed exists

seed

private long seed

the seed

ra

private java.util.Random ra

the random generator

Constructor Detail

RandomSampleActivity

public RandomSampleActivity(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.

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.