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Currently users may customize their JCas cover classes.  PEAR classpath isolation allows the use case where different customizations are present in one pipeline.  The current implementation supports this, and switches the set of JCas cover classes as Pear boundaries are crossed.  The idea of a Feature Structure being an instance of its cover class breaks down when multiple definitions of this exist.  Some ideas for fixing this.

Alternatives: generating JCas definitions from merged type systems

There are two approaches - more dynamic and less dynamic. 

  • Have a separate step, run outside of the UIMA runtime environment, which generates the full set of JCas classes (except the built-ins), from the merged type system
    • Configure the JVM classpath to include these classes typically at the front of the classpath.
  • Have an integrated approach, based on classloaders, that generate classes at type system merge (or lazily) and load them either all at once or via a special version of UIMAClassLoader, lazily.

More here.

Support parallel execution of components (if they don't depend on each other)