Necessity of Part 25 change supporting ONEOF?

[Jochen Haenisch]

David,
I think that your proposal below makes sense as it results in a superset of
the valid combinations for the case where UML and Express have different
functionality!
Best regards, Jochen.

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Jochen Haenisch			E-mail: Jochen.Haenisch at epmtech.jotne.com
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> -----Original Message-----
> From:	Bernd G. Wenzel [SMTP:bernd.wenzel at eurostep.com]
> Sent:	4. mars 2001 05:56
> To:	Lothar Klein
> Cc:	wg10 at steptools.com; xmlsc4 at nist.gov; wg11 at smiling.net
> Subject:	Re: Necessity of Part 25 change supporting ONEOF?
> 
> Lothar,
> 
> David's comment must be read in the context of Part 25, which
> should be useful outside of STEP. Therefore David is right.
> 
> You're addressing a different issue. The usage of EXPRESS by
> other parts of the STEP standard is questionable for many
> reasons. That's why it is sometimes nearly impossible to use
> off-the-shelf EXPRESS tools for performant STEP implementations.
> Some tools have STEP switches to control their execution. I agree
> with you, that this should be fixed, but I don't know, who is
> going to pay for it.
> 
> :-) Bernd
> 
> ----- Original Message -----
> From: Lothar Klein <lothar.klein at lksoft.com>
> To: David Price <dmprice at us.ibm.com>
> Cc: <wg10 at steptools.com>; <xmlsc4 at nist.gov>; <wg11 at smiling.net>
> Sent: Friday, March 02, 2001 9:47 PM
> Subject: Re: Necessity of Part 25 change supporting ONEOF?
> 
> 
> >
> > David,
> >
> > The problem here is more a political.
> > Do we just want to map EXPRESS with UML or do
> > we want to make STEP data models available in UML?
> > In the first case your proposals sounds good.
> > In the second case however it makes little sense since
> > the ONEOF and ANDOR stuff is more or less totally broken
> > in STEP data models. In actual APs and IRs there exist
> > soooo many valid but wrong ANDOR combinations that it
> > makes little sense to map this to UML.
> >
> > My proposal is to
> > - make EXPRESS rich enough to model "weak ONEOFs"
> > - go through all IRs and APs and use this new feature
> > - and then to map STEP with UML
> >
> > Am I the only one who thinks we should fix STEP?
> >
> > Lothar
> >
> >
> >
> > David Price wrote:
> > >
> > > Folks,
> > >
> > > I've thought a little more about this and believe that to
> allow the correct
> > > EXPRESS SUPERTYPE semantics to be somehow represented in UML
> we should do
> > > the following:
> > >
> > > 1 - If there is no SUPERTYPE constraint, specify the UML
> overlapping
> > > constraint.
> > > 2 - If there is exactly one ONEOF that covers all subtypes of
> an entity
> > > type, specify the UML disjoint contraint.
> > > 3 - In all other cases where any SUPERTYPE constraint is
> specified, specify
> > > the UML overlapping constraint.
> > >
> > > 1 and 2 should be clear. I'm proposing 3 because it allows
> for the overlaps
> > > that do occur in EXPRESS to be represented in the UML model.
> It does also
> > > allow more combinations in the UML than are legal in the
> EXPRESS but we
> > > can't allow fewer combinations - which is what happens if you
> specify
> > > disjoint (or nothing since disjoint is the default). We'll
> have to assume
> > > that when people create data, the AP or a usage guide they
> are using to
> > > explain what's legal will result in correct data generation.
> Perhaps as UML
> > > constraints are harmonized with EXPRESS constraints we can
> add more to the
> > > mappings in the future.
> > >
> > > Anyone disagree with this approach? Anyone agree?
> > > Thanks,
> > > David
>