RAS22 — Allow Models to be referenced from Assets and avoid duplicating UML

It's not at all clear how to use RAS to reference UML (or other) models
which might represent the design of a component, or might be reusable
assets in their own right - despite the fact that the Model may be in
the same repository as the RAS Asset definition!
The description of Artifact (in Section 2.4.10.1 of the RFC) clearly
implies that an Artifact must be (or refer to) a file: while it would be
possible to export a Model as a XMI file and reference it, this
dramatically reduces the possibility of proper management, editing and
impact analysis of the modeling elements, and should only be required
for physical interchange purposes. In fact requiring models to be
instantiated in XMI files ironically works against the reuse of the
model elements (e.g. common classes reused in the design of multiple
components).
The RAS Profile mechanism seems to require the construction of new
RAS-specific metamodels and does not seem readily to allow the re-use of
existing metamodels, models and tools such as UML.
For example, a more sensible approach for support of John Cheesman's
Component book would be to use a UML Profile (as indeed he does in the
book!) and allow the top level package to be linked to the Asset.
Similarly the UML Diagram Interchange standard already has a metamodel
for Diagrams (linked to model elements) so why create another
representation here?

Proposed resolution:
Allow artifacts to reference arbitrary model elements (this can be
achieved through an association to Reflective::Object which is the
implicit superclass of every class in a MOF 2 metamodel).
Allow a RAS Profile to refer to a Package (representing a metamodel or
UML Profile) rather than having to create its own metamodel.

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