Subject: Re: MSC-News: Problem with instance-oriented - shared in-line expression textual
From: UK496 Paul Baker (paul#bae231.comm.mot.com)
Date: Mon Oct 05 1998 - 08:21:23 GMT
The originator of this message is responsible for its content.
-----From UK496 Paul Baker <paul#bae231.comm.mot.com> to mscnews -----
> Dear Paul,
> can you give a simple example? I cannot see immediately your point because
> of the shared construct.
If we have two action boxes a and b each of which reside upon different
instances (I, J) within an 'alt' inline expression, it is not possible
to determine whether the expression has the choice of executing:
- action a followed by action b, or vice-versa
- action a or action b, not both.
Using the above example the instance-oriented grammar would look as
alt begin i,j;
action a; /* is this event part of the same choice as action b? */
alt begin i,j;
action b; /* is this event part of the same choice as action a? */
end instance J;
I hope this helps.
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Ekkart Rudolph wrote: > > The originator of this message is responsible for its content. > -----From Ekkart Rudolph <rudolphe#informatik.tu-muenchen.de> to mscnews ----- > > Paul Baker wrote: > > > Dear MSC folks, > > > > I think there is a problem regarding the instance-oriented textual > > grammar for the shared > > inline ‘alt’ and ‘par’ expressions (section 5.3 of Z.120), which: > > > >> > > > (2) makes it impossible to define the semantics for alt and par > > expressions using the > > instance-oriented grammar. The reason for this is that it is not > > possible (in some cases) > > given the information provided to determine which events, existing on > > different instances, > > are associated with different alt or par arguments. And in fact > > whether events are > > indeed associated with the same alt or par expression. > > Dear Paul, > can you give a simple example? I cannot see immediately your point because > of the shared construct. > > Apart from that, I do not like so much the terminology 'instance oriented' and > 'event oriented' grammar in MSC-96. In fact, my idea was to include the > 'instance oriented' representation of MSC-92 within the new 'event oriented' representation. > (since message inputs may appear before corresponding message outputs within this > 'event oriented' grammar) > > Unfortunately, because of upward compatability there still remained this > <old instance head statement>. Apart from that, I would rather distinguish between > <shared event> - and <multi instance event> representation (e.g. with respect to > conditions and inline expressions). I must admit that the <shared event> - representation > in some parts (e.g. inline expression) resembles the original 'instance oriented' > representation, in order to avoid the obscuring mixing of events on different instances > within operator expressions. > > Best regards! > Ekkart > > ================================================================================= > Dr. Ekkart Rudolph phone: +49 89 289 25361 > Technische Universitaet Muenchen fax: +49 89 289 28183 > Institut fuer Informatik, email: rudolphe#informatik.tu-muenchen.de > c/o Lehrstuhl Prof. Broy > Arcisstrasse 21 > D - 80290 Muenchen > ================================================================================= > > -----End text from Ekkart Rudolph <rudolphe#informatik.tu-muenchen.de> to mscnews ----- > For help, email "majordomo#sdl-forum.org" with the body of your email as: > help > or (iff this does not answer your question) email: owner-mscnews#sdl-forum.org
-----End text from UK496 Paul Baker <paul#bae231.comm.mot.com> to mscnews ----- For help, email "majordomo#sdl-forum.org" with the body of your email as: help or (iff this does not answer your question) email: owner-mscnews#sdl-forum.org
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