Interfaces for `Resources` and `ResourceSpecifiers`.

{@link org.apache.uima.resource.Resource} is the general term for all UIMA components that can be acquired and used by an application (or by other resources).

`Resource`s may be co-located with their client or distributed as services. This is made transparent to the client.

A {@link org.apache.uima.resource.ResourceSpecifier} contains information that can be used to acquire a reference to a `Resource`, whether that is done by instantiating the resource locally or locating an existing resource available as a service.

The {@link org.apache.uima.ResourceFactory} takes a `ResourceSpecifier` and returns an instance of the specified `Resource`. Again, this can be done by creating the instance or by locating an existing instance.

Most applications will not need to deal with this abstract `Resource` interface. UIMA Developers who need to introduce new types of Resources, however, will need to implement the interfaces in this package.