EMF Facet is a new Eclipse/Modeling project which will provide solutions to extend existing metamodels without changing them. It has been provisioned recently in EMFT by Greg Dupé of Mia-Software, the co-leader of the project.
With EMF Facet, it will be more easy to dynamically extend and customize a tool based on EMF.
The idea is to allow defining new attributes, new relations and new types in a non-intrusive way (you can read this older post about EMF Facet).
This mechanism has already been developped in the MoDisco project (the Eclipse/Modeling project dedicated to Software Modernization). It is completed by a QueryManager component which allow executing queries on a EMF model independently from the query technology (bridges for OCL, Java and XPath are already available). As it is independent from Software Modernization purposes, the corresponding code is going to move to this new EMF Facet project.
After some refactoring, it will be enriched with other components (such as customizable widgets to display extended EMF models). First version is planned to be ready in June 2011 for Indigo, the next Eclipse release. Before this date, early versions will be available with intermediate Indigo milestones.
To know more about this project, don't miss the talk EMF Facet: a Non-Intrusive Metamodel Extension Tooling, Thursday, the 4th of November during Eclipse Summit Europe 2010, in Germany.