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From: warda@veronica.informatik.uni-dortmund.de (Armin M. Warda)
Newsgroups: comp.lang.beta
Subject: PDES / Concurrency in the BETA Language
Date: 11 Apr 1995 11:50:43 GMT
Organization: CS Department, Dortmund University, Germany
Lines: 60
Sender: warda@veronica (Armin M. Warda)
Distribution: world
Message-ID: <3mdqej$6sd@fbi-news.informatik.uni-dortmund.de>
Reply-To: warda@ls4.informatik.uni-dortmund.de (Armin M. Warda)
NNTP-Posting-Host: veronica.informatik.uni-dortmund.de
Summary: Is there a version of BETA supporting real concurrency and multiprocessors? Experience with BETA and PDES?
Keywords: PDES,parallel,discrete,event,simulation,Mjølner,BETA,concurrency

As a computer science student at 'Universität Dortmund'
I am writing a thesis in the field 'Parallel Discrete
Event Simulation (PDES)'.

SIMULA has been applied with great success to 'Discrete
Event Simulation (DES)'. One of SIMULA's strength (with
respect to DES) is the concept of 'coroutines', but SIMULA
lacks concepts for 'concurrency'.

I am wondering if BETA - being in the SIMULA tradition and
containing a powerful concept for concurrency - could be
applied to PDES with comparable success.

Thus currently I am evaluating the BETA language:

I am using the Mjølner BETA System version 5.0(2) for Linux
(Intel 386/486), Personal Edition ('Sonderlizenz für den
Fachbereich Informatik, Universität Dortmund').

This version does NOT support pre-emptive multitasking:

  "THE CONCURRENCY IS SIMULATED
   In order to implement real concurreny, an interrupt
   mechanism must be implemented. This is currently NOT done.
   A component/system will thus keep the control until it
   makes an explicit or implicit SUSPEND. An implicit SUSPEND
   is made when a component must wait for a semaphore, executes
   the pause pattern, executes the sleep pattern, or performs a
   blocking communication using the shellEnv distribution
   abstractions (not described in this manual). As the
   concurrency is simulated, there is no difference between the
   implementation of the alt and conc imperatives."

[The Mjølner BETA System Basic Libraries Reference Manual,
MIA 90-08(1.2), August 1994, chapter 11, page 95 and preamble
of 'basicsystemenv.bet']

   1. Is there a version of BETA that supports real concurrency?

   2. Will there be a version that supports real concurrency
      in the near future?
 
   3. Is there a version that supports multiprocessors (eg. for
      SUN Workstations with Solaris 2)?

   4. Will there be a version that supports multiprocessors in
      the near future?

   5. Has anybody already applied BETA successfully to 'Discrete
      Event Simulation'?

   6. Has anybody already applied BETA successfully to
      '_PARALLEL_ Discrete Event Simulation'?

Any hints and pointers to other sources of information are
welcome. Please eMail me: <warda@ls4.informatik.uni-dortmund.de>
I will post a summary to this newsgroup.

Yours sincerely,
Armin M. Warda