Several Jiras talk about wanting external shared resources that can be configured using the standard UIMA configuration settings and parameters.
For example: https://issues.apache.org/jira/browse/UIMA-2979. Currently, there is one UIMA external resource descriptor that supports this, which is the configurableDataResourceSpecifier. It has a resourceMetaData sub-element, which, in turn, has the configurationParameters and configurationParameterSettings elements. There is an alternate, simpler approach to configuring external resources, now available (as of UIMA 2.9.0) - using direct access to the External Configuration parameters. See section 2.4.3.5 in the UIMA Reference book. The idea is that each External Resource would define its own set of key-value parameter settings, and retrieve them at run time. The normal UIMA Configuration parameter mechanism is overlayed with lots of complex functionality. Some examples of this include supporting overrides in UIMA Aggregates, grouping of sets of alternative values with both some common parameters and some non-common ones (where the group can be programmatically picked at run time (e.g., by the document language), extra meta data (such as type, flags (e.g. mandatory)), and so forth. This extra complexity was created for use cases where these configuration parameters were interpreted with respect to a UIMA Context (that is, where the parameters were associated with a particular position within an aggregation hierarchy for a pipeline). I think that some of these mechanisms probably don't work correctly, if applied to the nested configuration parameter specs inside the resourceMetaData of a configurableDataResourceSpecifier. I'm thinking it would not be worth the trouble to add support to allow full support for UIMA Configuration Parameters and settings in External Resources, because I think the (now available) External Configuration capabilities provide sufficient capability for this, and fit better with the basic idea of External Resources as being shared objects for a pipeline (or set of pipelines). I'd be interested to hear other views, especially if you think External Resources is adequate, or insufficient for this. -Marshall
