Re: MSC-News: Gate semantics in MSC'96

Subject: Re: MSC-News: Gate semantics in MSC'96
From: Dmitry Zhukov (
Date: Thu Aug 20 1998 - 12:06:05 GMT

The originator of this message is responsible for its content.
-----From Dmitry Zhukov <> to mscnews -----

Dear Rudolph,

thank you very much for your answer. Now I see that there
are some possible interpretations I didn't think about.

On Wed, 19 Aug 1998, Ekkart Rudolph wrote:

> Concerning your first problem, the implicit gate names should of
> course be made unique by means of an identifier.

The problem that I try to solve is to analyse the examples from
Z.120 by our automatic tool. Our tool cannot analyse the example
from section 6.1:

msc connection;
  inst calling_party : process digite,
       called_party : process digite;
  instance calling_party : process digite;
    condition Idle shared all;
    in off_hook from env;
    out dial_tone_on to env;
    in digit from env; /* first output */
    out dial_tone_off to env;
    in digit from env; /* second output */
    out seizure_int to called_party;
    in ack from called_party;
    out ring_back_tone_on to env;
    condition Seizure shared all;
    in answer from called_party;
    out connection to env;
    condition Talking shared all;
  instance called_party : process digite;
    condition Idle shared all;
    in seizure_int from calling_party;
    out ack to calling_party;
    out internal_rining_on to env;
    condition Seizure shared all;
    in off_hook from env;
    out answer to calling_party;
    condition Talking shared all;


This example contains two sendings of message 'digit' and
'off_hook' to the environment. This results in two
'out_digit' and two 'out_off_hook' gates and
our tool reports a "Duplicate gate name" error.
I think of the following ways to solve this problem:

1. Add a explicit gate 'g' to the diagram and
   add a keyword 'via g' to the second output.
   (The original version of the msc 'connection' thus
   is regarded as incorrect).

   As the situation when a message is sent several
   times to the environment is common (e.g. for
   simulation traces) this solution I think is
   something inconvinient.

2. Modify the rules for implicit gates naming.
   For example one can add an unique integer
   numbers to implicit gate names.

3. Allow a diagram to have several implicit
   (or also explicit ?) gates with the same name.

4. What else ? ...

What the members of the MSC community think
of this problem ?

Best regards,

> > 1. Implicit gates
> >
> > According to the Z.120, paragraph 4.4,
> >
> > a message gate always has a name. The name can be
> > defined explicitly by a name associated with the gate on
> > the frame. Otherwise the name is given implicitly by
> > the direction of the message through the gate and the
> > message name, e.g. "in_X" for a gate receiving a message
> > X from its environment.
> >
> > This rule works good in the most cases. In the following
> > example however its application results in two gates
> > with equal (implicit) names:
> >
> > msc m_twice;
> > instance a;
> > out m to env comment via in_m;
> > out m to env comment via in_m;
> > endinstance;
> > endmsc;
> >
> > In my opinion the possibility of having several gates
> > with the same name makes the language difficult to analyse.
> > Note also that the example above a correct as MSC'92
> > specification. Can somebody clarify this problem ?

-----End text from Dmitry Zhukov <> to mscnews -----
For help, email "" with the body of your email as:
or (iff this does not answer your question) email:

This archive was generated by hypermail 2a23 : Wed Jun 19 2013 - 13:16:38 GMT