Re: MSC-News: The loop operator

Subject: Re: MSC-News: The loop operator
From: Dmitry Zhukov (
Date: Tue Aug 18 1998 - 14:01:46 GMT

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

Dear Dagbjorn,

On Fri, 30 Jan 1998, Dagbjorn Nogva wrote:

> Dear MSC-community,
> Does the loop operator denote a parallel loop or a sequential
> loop? By parallel loop I mean that all iterations are executed
> in parallel.
> As far as I can see, Z.120 doesn't say anything specific, however
> I guess the answer is sequential loop, i.e. each iteration is
> executed in sequence. If so, is it possible to specify a parallel
> loop by combining the par operator and the loop operator in some
> way? Or do I just have to make a comment?

Another way to specify a parallel loop is to use
recursive MSC definitions. The following example describes
sending a message several times "in parallel":

  msc parallel_loop;
    inst sender, receiver;

    sender: instance;
    receiver: instance;
    all: alt begin;
      all: condition all_sent;
                    condition send_one_more;
      all: par begin;
        sender: out m to receiver;
        receiver: in m from sender;
        all: reference parallel_loop;
                    par end;
    all: alt end;
    sender: endinstance;
    receiver: endinstance;

The question is if the formal MSC semantics allows
such definitions.

Best regards,

-----End text from Dmitry Zhukov <> to mscnews -----
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