Examples of AnalysisComponent

• org.apache.uima.analysis_component.AnalysisComponent
  Analysis Components are the primitive "building blocks" from which UIMA solutions are built. This is the common superinterface for all user-developed components that take a CAS as input and may produce CASes as output.

  Typically, developers do not implement this interface directly. There are several abstract classes that you can inherit from depending on the function that your component performs and which CAS interface it uses:

  • Annotator: Receives an input CAS and updates it
    • {@link JCasAnnotator_ImplBase}: Uses JCas interface
    • {@link CasAnnotator_ImplBase}: Uses CASinterface
  • {@link org.apache.uima.collection.CasConsumer_ImplBase}: Receives an input CAS but does not update it. May update a data structure based on information in the CASes it receives.
  • CasMultiplier: Receives an input CAS and, in addition to updating it, may output new CASes. One common use of this is to split a CAS into pieces, emitting each piece as a separate output CAS.
    • {@link JCasMultiplier_ImplBase}: Uses JCas interface
    • {@link CasMultiplier_ImplBase}: Uses CAS interface
    • {@link org.apache.uima.collection.CollectionReader_ImplBase}: A special type of CasMultiplier that, for historical reasons, does not take an input CAS.

  The framework interacts with AnalysisComponents as follows:

  1. The framework calls the AnalysisComponent's {@link #process(AbstractCas)} method with aninput CAS.
  2. The framework then calls the AnalysisComponent's {@link #hasNext()} method, which shouldreturn true if the AnalysisComponent intends to produce new output CASes, or false if the AnalysisComponent will not produce new output CASes.
  3. If the AnalysisComponent returns true, the framework will then call the {@link #next()} method.
  4. The AnalysisComponent, in its next method, can create a new CAS by calling {@link UimaContext#getEmptyCas(Class)} (or instead, one of the helper methods in the ImplBaseclass that it extended). It then populates the empty CAS and returns it.
  5. Steps 2 & 3 continue for each subsequent output CAS, until hasNext() returns false.

From the time when process is called until the time when hasNext returns false, the AnalysisComponent "owns" the CAS that was passed to process. The AnalysisComponent is permitted to make changes to this CAS. Once hasNext returns false, the AnalysisComponent releases control of the initial CAS. This means that the AnalysisComponent must finish all updates to the initial CAS prior to returning false from hasNext.

However, if the process method is called a second time, before hasNext has returned false, this is a signal to the AnalysisComponent to cancel all processing of the previous CAS and begin processing the new CAS instead.