org.apache.uima.flow
Class FlowController_ImplBase

java.lang.Object
  org.apache.uima.flow.FlowController_ImplBase

All Implemented Interfaces:

FlowController

Direct Known Subclasses:

CasFlowController_ImplBase, JCasFlowController_ImplBase

public abstract class FlowController_ImplBase
extends Object
implements FlowController

Implementation base class for FlowControllers. Normally developers do not extend this class directly. Instead use JCasFlowController_ImplBase or CasFlowController_ImplBase, depending on which CAS interface you would like to use.

This class implements the initialize(FlowControllerContext) method and stores the FlowControllerContext in a private field where it can be accessed via the getContext() method.

This class also provides a "dumb" implementation of the reconfigure() method, which simply calls destroy() followed by initialize(FlowControllerContext). Developers of FlowControllers with expensive initialization logic should override this method and provide a more intelligent implementation.

Constructor Summary

FlowController_ImplBase()

Method Summary

void	addAnalysisEngines(Collection<String> aKeys) Does nothing by default.
void	batchProcessComplete() Completes the processing of a batch of CASes.
void	collectionProcessComplete() Notifies this component that processing of an entire collection has been completed.
void	destroy() Frees all resources held by this FlowController.
protected FlowControllerContext	getContext() Gets the FlowControllerContext for this FlowController.
void	initialize(FlowControllerContext aContext) Performs any startup tasks required by this component.
void	reconfigure() Alerts this FlowController that the values of its configuration parameters or external resources have changed.
void	removeAnalysisEngines(Collection<String> aKeys) Throws an AnalysisEngineProcessException by default.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.uima.flow.FlowController

computeFlow, getRequiredCasInterface

Constructor Detail

FlowController_ImplBase

public FlowController_ImplBase()

Method Detail

initialize

public void initialize(FlowControllerContext aContext)
                throws ResourceInitializationException

Description copied from interface: FlowController

Performs any startup tasks required by this component. The framework calls this method only once, just after the FlowController has been instantiated.

The framework supplies this FlowController with a reference to the FlowControllerContext that it will use, for example to access configuration settings or resources. This FlowController should store a reference to this Context for later use.

Specified by:

initialize in interface FlowController

Parameters:

aContext - Provides access to services and resources managed by the framework. This includes configuration parameters, logging, and access to external resources. Also provides the FlowController with the metadata of all of the AnalysisEngines that are possible targets for routing CASes.

Throws:

ResourceInitializationException - if the FlowController cannot initialize successfully.

reconfigure

public void reconfigure()
                 throws ResourceInitializationException,
                        ResourceConfigurationException

Description copied from interface: FlowController

Alerts this FlowController that the values of its configuration parameters or external resources have changed. This FlowController should re-read its configuration from the UimaContext and take appropriate action to reconfigure itself.

In the abstract base classes provided by the framework, this is generally implemented by calling destroy followed by initialize. If a more efficient implementation is needed, you can override that implementation.

Specified by:

reconfigure in interface FlowController

Throws:

ResourceInitializationException - if this component encounters a problem in reinitializing itself from the new configuration

ResourceConfigurationException

batchProcessComplete

public void batchProcessComplete()
                          throws AnalysisEngineProcessException

Description copied from interface: FlowController

Completes the processing of a batch of CASes. The size of a batch is determined based on configuration provided by the application that is using this component. The purpose of batchProcessComplete is to give this component the change to flush information from memory to persistent storage. In the event of an error, this allows the processing to be restarted from the end of the last completed batch.

If this component's descriptor declares that it is recoverable, then this component is required to be restartable from the end of the last completed batch.

Specified by:

batchProcessComplete in interface FlowController

Throws:

AnalysisEngineProcessException - if this component encounters a problem in flushing its state to persistent storage

collectionProcessComplete

public void collectionProcessComplete()
                               throws AnalysisEngineProcessException

Description copied from interface: FlowController

Notifies this component that processing of an entire collection has been completed. In this method, this component should finish writing any output relating to the current collection.

Specified by:

collectionProcessComplete in interface FlowController

Throws:

AnalysisEngineProcessException - if this component encounters a problem in its end-of-collection processing

destroy

public void destroy()

Description copied from interface: FlowController

Frees all resources held by this FlowController. The framework calls this method only once, when it is finished using this component.

Specified by:

destroy in interface FlowController

addAnalysisEngines

public void addAnalysisEngines(Collection<String> aKeys)

Does nothing by default. Subclasses may override this to support adding new AnalysisEngines to the flow.

Specified by:

addAnalysisEngines in interface FlowController

Parameters:

aKeys - a Collection of Strings, each of which is the key of an Analysis Engine to which CASes can be routed. These are the same keys as used in FlowControllerContext.getAnalysisEngineMetaDataMap().

See Also:

FlowController.addAnalysisEngines(java.util.Collection)

removeAnalysisEngines

public void removeAnalysisEngines(Collection<String> aKeys)
                           throws AnalysisEngineProcessException

Throws an AnalysisEngineProcessException by default. Subclasses may override this to support removing AnalysisEngines from the flow.

Specified by:

removeAnalysisEngines in interface FlowController

Parameters:

aKeys - a Collection of Strings, each of which is the key of an Analysis Engine to which CASes may no longer be routed.

Throws:

AnalysisEngineProcessException - if the FlowController cannot continue with these Analysis Engines removed, or doesn't support removing Analysis Engines at all.

See Also:

FlowController.removeAnalysisEngines(java.util.Collection)

getContext

protected FlowControllerContext getContext()

Gets the FlowControllerContext for this FlowController. This provides access to configuration parameters, resources, and also to metadata for each AnalysisEngine that is available for this FlowController to route CASes to.

Returns:

the FlowControllerContext for this FlowController