Metacat

MNQuery.listQueryEngines() will return these engines: {"pathquery", "solr"} and we'd call MNQuery.query("solr", <solrQuerySyntax>) to get a stream of solr results back depending on the structure of the original query (might return xml or json etc).

See: http://mule1.dataone.org/ArchitectureDocs-current/apis/MN_APIs.html#MNQuery.query

Where "Metacat docs" include:
-Currently indexed DataONE science metadata (EML versions, FGDC versions, Dryad)
-SystemMetadata
-ORE objects
-Any additional XML schema**

**When adding a new schema to be indexed by Metacat here are some requirements:
-Metacat admin should have complete control over which xpath expressions map to which fields in the current index.
-Configuration should allow for: adding new fields, specifying the type (string, number, boolean, etc) of the field, specifying the name of the field, and mapping one or more xpath expressions to the field.
-If there is currently no appropriate field in the index, then the administrator should be able to easily add a new field to the index to accommodate the new xpath.
-Metacat should not be at the mercy of DataONE to augment the fields or objectFormats that are indexed. It should incorporate enhancements from DataONE if desired, but Metacat should be able to blaze the trail on indexing new content before the CN stack implements similar behavior.

Original Bugzilla ID was 5810