Re: MSC-News: Incomplete messages


Subject: Re: MSC-News: Incomplete messages
From: Oystein Haugen (oystein.haugen#ericsson.no)
Date: Thu Aug 20 1998 - 12:13:08 GMT


The originator of this message is responsible for its content.
-----From Oystein Haugen <oystein.haugen#ericsson.no> to mscnews -----

Dear friends of black holes

I believe Mr. Zhukov has found an error in the textual form of example
6.21 of Z.120 of 1996. According to my opinion the input event should
simply be removed. The ICON message never reaches the Responder and the
Responder thus has no event attached.

I still think that the example is graphically correct describing that
the ICON message is actually lost. An incomplete message has only one
event.

Yours
Oystein Haugen
Rapporteur MSC

Jan Docekal wrote:

> The originator of this message is responsible for its content.
> -----From Jan Docekal <jan.docekal#telelogic.se> to mscnews -----
>
> Dear Dimitry,
>
> I must admit that i missed your point first time i read your question.
>
> It is my opinion that the /* input event */ should not be present in
> the
> example below. My opinion is however contradicted to some extent by
> the
> example "6.21 High-Level MSC with alternate comosition, msc message
> lost", which contains the same construct as the example below.
>
> My opinion is however that both the examples are wrong. What happens
> if
> a message is lost to an instance that is not present in the current
> msc?
> Another problem is that there seems to be no natural point where the
> lost messages should be "recieved". In the example below the lost
> message is "recieved" between conditions, but what happens if other
> messages where exchanged between Initiator and Responder. It is
> impossible to show graphically that an event is "not recieved" between
>
> two messages at the Responder. To mee it seems quite natural that if
> the
> mesage is lost, it is per definition not recieved by the intended
> reciever (and then there should be no evidence of such an activity in
> the textual representation of the diagram).
>
> I would like other members to give their opinions (or even better
> knowledge) in this matter, since I seem to be unable to answer simple
> questions on the first try:-)
>
> Cheers,
> Jan.
>
> > -----Original Message-----
> > From: Dmitry Zhukov [SMTP:dmjr#ispras.ru]
> > Sent: den 20 augusti 1998 12:41
> > To: Jan Docekal
> > Cc: mscnews#sdl-forum.org
> > Subject: RE: MSC-news: Incomplete messages
> >
> > The originator of this message is responsible for its content.
> > -----From Dmitry Zhukov <dmjr#ispras.ru> to mscnews -----
> >
> > Dear Jan,
> >
> > On Thu, 20 Aug 1998, Jan Docekal wrote:
> >
> > > It is correct.
> > >
> > > Possible interpreatations follows:
> > >
> > > Instance A sends message M to instance B. After M is sent, but
> > before M
> > > is recieved, B is (inexpectedly) terminated. Message B still knows
>
> > that
> > > it was on its way to B, but can no longer find it.
> > >
> > > I think that the possibility to specify the reciever of the lost
> > > messages is most useful when making a trace of a system execution,
>
> > > rather than when specifying system behaviour.
> >
> > I agree with you that specifying the receiver of lost messages
> > is often useful. It is unclear to me, why an *input event* is
> > specified for the lost message. I think that if both output and
> > input events are known for a message it is better to use a general
> > message rather then a lost.
> >
> > Best regards,
> > Dmitry.
> >
> > > > I have a question of incomplete message events in MSC'96.
> > > > Consider the following example from Recommendation Z.120,
> > > > section 6.6:
> > > >
> > > > msc failure; inst Initiator, Responder;
> > > > instance Initiator;
> > > > condition Disconnected shared all;
> > > > in ICONreq from env;
> > > > set T;
> > > > out ICON to lost Responder; /* output event */
> > > > condition Wait_For_Resp shared all;
> > > > timeout T;
> > > > out IDISinf to env;
> > > > condition Disconnected shared all;
> > > > endinstance;
> > > >
> > > > instance Responder;
> > > > condition Disconnected shared all;
> > > > in ICON from Initiator; /* input event */
> > > > condition Wait_For_Responder shared all;
> > > > condition Disconnected shared all;
> > > > endinstance;
> > > > endmsc;
> > > >
> > > > As described in section 4.3,
> > > >
> > > > An incomplete message is a message which is either an output
> > > > (where the input is lost) or an input (where the output is
> > > > unknown)
> > > >
> > > > But in the example above the input is specified for the
> > > > lost message ICON. How should one understand this example ?
> > > > Is it correct ?
> >
> >
> > -----End text from Dmitry Zhukov <dmjr#ispras.ru> 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 Jan Docekal <jan.docekal#telelogic.se> 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

--
------------------------
Oystein Haugen, Ericsson as. , P.O. box 34, N-1361 Billingstad, Norway
Tel: +47 66 84 23 46 Fax: +47 66 84 19 15 Mob: +47 913 90 914
E-mail: oystein.haugen#ericsson.no

-----End text from Oystein Haugen <oystein.haugen#ericsson.no> 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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