[higgins-dev] Changes to IdAS.model utility package

["Paul Trevithick" <paul@xxxxxxxxxxxxxxxxx>]

Valery,

At the F2F Raj (IBM) and Tom (Novell) both suggested a change to the design
of your proposed IdAS model package. The proposal was that if the IdAS
consumer wants to inspect the model of, say, an attribute we would make this
an explicit two step: first, the consumer would look up the type (URI) of
the attribute and second it would hand this URI to the .model package to get
back its model.

This is a change from your current design. Beyond Raj and Tom's motivations,
this approach has one distinct advantage over your current proposal wherein
the attribute can be directly queried as to its model (in one step instead
of two). The advantage that I see is that it allows us to support a new
possibility: where the attribute's "model" metadata not managed locally by
the Context Provider (e.g. as retrievable by our 'getSchema' method), but in
fact exists as metadata document retrievable by dereferencing the
attribute's type URI (URL in this case) and using either WS-Addressing to
retrieve the attribute's type metadata or doing an HTTP GET and reading an
XRDS document. 

The consumer would pass the URI to a general purpose query method in the
IdAS.model package and it would (a) first search for the local schema for
this attribute's containing Context, and then if it didn't find any OWL
metadata "about" this URI, would then (b) attempt to dynamically retrieve
the OWL metadata by dereferencing the URI and using WS-Addressing or OASIS
XRI/XRDS as described above.

We do NOT need to implement (b) right now. I'm only adding support for Tom
and Raj's suggestion that we decouple the .model package a bit, use the two
step lookup method, and have a more general purpose query method in the
.model package.

-Paul