View source for VIATRA/Query/DeveloperDocumentation/QueryEngineArchitecture

== VIATRA Query Engine Internals ==

=== Overview ===
[[File:IncQueryEngine.png]]

=== Most important concepts ===

* '''ViatraQueryEngine''': the central element of the API.
* '''QueryScope''': the set of model elements the ViatraQueryEngine should work on.
** The project itself implements only '''EMFScope''' right now.
* '''IQueryRuntimeContext''': wrapper class for the query backends to access the model. The access can be both indexed and non-indexed.
* '''IQueryBackend''': an executor of graph pattern matches; it instantiates '''IQueryResultProvider'''s. Query Backends needs to be registered to the ViatraQueryEngine itself.
** '''RetePatternMatcher''' is the fully incremental implementation of the '''IQueryResultProvider''' interface.
** '''LocalSearchResultProvider''' is a local search based implementation of the '''IQueryResultProvider''' interface.
* The '''ViatraQueryMatcher''' interface is the public matcher API: generated instances are type-safe.