[sc34wg3] SIDP vs Assertion types

[Robert Barta]

On Tue, Apr 22, 2003 at 06:23:29PM +0200, Jan Algermissen wrote:
> Yes. This is a basic design decision to be made by TMAs: Is a relationship to
> be modeled as an assertion or as a property.
...
> > The two extremes being one where I
> > do everything as SIDPs/OPs and the other where I do everything with
> > assertion types.
> 
> Exactly. If you do everything as properties you'd end up with something
> like a relational schema that only has relations (tables) that represent
> entity classes and no relations (tables) that represent relationship classes.

Jan,

This explanation was very helpful to me, thx!

So, is it a fair statement to say that TMM is meant as a platform
("bus") to integrate data repositories (relational DBs, XMLlish data,
other TMish data) into ONE common data framework?

If so, then I would have assumed that the propagators have thoughts
and/or experiments on this for relational data? The HTTPGET
application is certainly fascinating, but would not fully demonstrate
the strength of this approach to me. OTOH, you probably would have
used that already if you had.

Anyway, is this meant for read-only purposes?

  - application A uses relational DB and a TMA_A describes how to
    "view" the data TMish

  - application B models its data as TMA_B and can use data from A

Or is this also meant in both directions: read and write?

And what about querying? If application B makes a query, is this query
translated into TM-speak via TMA_B and then propagates to A and is
executed using the inverse of TMA_A.

Or is my understanding too mechanical and no formalisation of TMA
definitions can exist? But then how can we formally test TMM
conformance of an application?

\rho