org.apache.uima.examples.flow
Class WhiteboardFlowController

java.lang.Object
  org.apache.uima.flow.FlowController_ImplBase
      org.apache.uima.flow.CasFlowController_ImplBase
          org.apache.uima.examples.flow.WhiteboardFlowController

All Implemented Interfaces:

FlowController

public class WhiteboardFlowController
extends CasFlowController_ImplBase

FlowController implementing a simple version of the "whiteboard" flow model. Each time a CAS is received, it looks at the pool of available AEs that have not yet run on that CAS, and picks one whose input requirements are satisfied.

Limitations: only looks at types, not features. Ignores languagesSupported. Does not handle multiple Sofas or CasMultipliers.

Constructor Summary

WhiteboardFlowController()

Method Summary

Flow	computeFlow(CAS aCAS) This method must be overriden by subclasses.
void	initialize(FlowControllerContext aContext) Performs any startup tasks required by this component.

Methods inherited from class org.apache.uima.flow.CasFlowController_ImplBase

computeFlow, getRequiredCasInterface, typeSystemInit

Methods inherited from class org.apache.uima.flow.FlowController_ImplBase

addAnalysisEngines, batchProcessComplete, collectionProcessComplete, destroy, getContext, reconfigure, removeAnalysisEngines

Methods inherited from class java.lang.Object

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

Constructor Detail

WhiteboardFlowController

public WhiteboardFlowController()

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

Overrides:

initialize in class FlowController_ImplBase

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.

computeFlow

public Flow computeFlow(CAS aCAS)
                 throws AnalysisEngineProcessException

Description copied from class: CasFlowController_ImplBase

This method must be overriden by subclasses. It takes a CAS and returns a Flow object that is responsible for routing this particular CAS through the components of this Aggregate. The Flow object should be given a handle to the CAS, so that it can use information in the CAS to make routing decisions.

FlowController implementations will typically define their own class that implements Flow by extending from the base class CasFlow_ImplBase. This method would then just instantiate the flow object, call its setCas method to provide a handle to the CAS, and return the flow object.

Specified by:

computeFlow in class CasFlowController_ImplBase

Parameters:

aCAS - the CAS to be routed

Returns:

a Flow object that will be used to route aCAS

Throws:

AnalysisEngineProcessException - if a problem occurs during processing

See Also:

FlowController.computeFlow(AbstractCas)