Report on Common Framework Meetings

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  Preparatory Meeting, 17-18 September, Soria Moria, Norway
  IFIP WG14.3 Meeting, 18-19 September, Soria Moria, Norway
  Larch Discussion Meeting, 23 September, Soria Moria, Norway
  Work Items and Mailing Lists
  Urgent - Deadline 1 November 1995
  Deliverables - Tentative Plan
  Future Meetings - Tentative Plan
  WWW Home Page


An open collaborative effort has been initiated: to design a 

        Common Framework for Algebraic Specification.  

The rationale behind this initiative is that the lack of such a
framework greatly hinders the dissemination and application of
research results.  In particular, the proliferation of specification
languages, some differing in only quite minor ways from each other, is
a considerable obstacle for the use of algebraic methods in industrial
contexts, making it difficult to exploit standard examples, case
studies and training material.  A common framework with widespread
support throughout the research community is urgently needed.

The initiative has been started by COMPASS (ESPRIT Basic Research
WG 6112), in cooperation with IFIP WG 14.3 (Foundations of
Systems Specification), but participation is already not confined to
members of those groups.  Some 25 leading researchers in algebraic
specification have already agreed to participate, and others are being
invited to join.

The current aim is to base the common framework as much as possible on
a critical selection of features that have already been explored in
various contexts.

* PREPARATORY MEETING, 17-18 September, Soria Moria, Norway

Following the discussions during the COMPASS Day at Aarhus, 26-27 May
1995, it was decided to hold a working meeting on the Common Framework
(previously referred to as the `unifying framework') at Soria Moria,
Norway, immediately prior to the IFIP WG14.3 meeting and COMPASS/WADT
meetings at the same place.  The purpose of this meeting was to
discuss issues of specification language design with reference to the
Common Framework Initiative and to prepare a presentation on this
topic for the IFIP meeting.

Some moderated mailing lists (unif-lang, -tool, -meth, -flex, -high)
were established at Aarhus at the beginning of July, intended for
circulation of position statements concerning selection of constructs
from existing languages.  By early September, 6 contributions had been
made on unif-lang and 1 on unif-meth (the archives of the mailing lists
are accessible via the Common Framework WWW Home Page, specified at
the end of this message).

The meeting was attended from the start on Sunday morning by 19 of us: 

Egidio Astesiano, Michel Bidoit, Christine Choppy, Ole-Johan Dahl,
Jose Fiadeiro, Marie-Claude Gaudel, Jim Horning, Helene Kirchner,
Hans-Joerg Kreowski, Bernd Krieg-Brueckner, Tom Maibaum, Grant
Malcolm, Peter D. Mosses, Fernando Orejas, Olaf Owe, Gianna Reggio,
Don Sannella, Andrzej Tarlecki, Michal Walicki.

The discussion was lively, and the mood constructive.  The chairman of
IFIP WG14.3 announced that we would be able to continue our
discussions during most of that meeting, giving us almost 2.5 days
altogether for working on the Common Framework Initiative.

A lot of pertinent points were made during the discussions.  We used a
`check-list' provided by Bernd Krieg-Brueckner to help structure the
discussion a bit.  Also, Don Sannella handed out a draft of a chapter
on Specification Languages (by Don Sannella and Martin Wirsing) from
the forthcoming IFIP State-of-the-Art Report; it surveys major
existing languages and discusses many design issues (it is available
on WWW at URL http://www.dcs.ed.ac.uk/~dts/pub/spec-lang.ps).

By Monday midday we felt that we had made significant progress with
clarifying some of our aims, and had discussed a few technical issues;
but we were still a long way from being able to formulate our
requirements for the Common Framework language(s).

* IFIP WG14.3 MEETING, 18-19 September, Soria Moria, Norway

As well as most of the participants of the preparatory meeting, 11
others attended the IFIP meeting from Monday afternoon (some of them
also Monday morning):

Didier Bert, Mohammed Bettaz, Hans-Dieter Ehrich, Hartmut Ehrig, Harald
Ganzinger, Pierre Lescanne, Karl Meinke, Peter Padawitz, Horst
Reichel, Pippo Scollo, Eric Wagner.

We started with a brief resume of the motivation for the Common
Framework initiative and of the progress made during the preparatory
meeting.  It was hardly adequate for the new participants, but we
wanted to press on and not spend a long time repeating the arguments
from the previous discussions.

Then Michel Bidoit led a session focussing on tool support in the
Common Framework.  We identified different classes of tools,
including: editors and parsers; interpretors; verifiers; development
managers; library browsers; translators; and tools for net

The afternoon concluded with the IFIP WG14.3 Business Meeting.

Tuesday morning started with a session on Methodology, led by
Marie-Claude Gaudel.  Issues discussed included: relation to language
constructs, such as modules and parameterization; flexibility; and
integration with semi-formal methods.

We continued by addressing the relationship between specifications and
programs.  The approach taken in Larch was discussed in detail: a
single shared language for specifying data types, an interface
language for each programming language for specifying programs.

Then we came to listing the urgent work items for the Common Framework
Initiative - and to getting volunteers to commit themselves to dealing
with them!  The enthusiasm of the volunteering bodes well for the
future of this initiative.

The IFIP meeting was concluded by a discussion of the role that term
rewriting might play in connection with the Common Framework.

A list of tentative requirements and design choices for the Common
Framework languages, extracted from the various discussions at Soria
Moria, will soon be available via the Common Framework WWW Home Page
(see the end of this message).  One important design decision that
needs mentioning here concerns the structuring of the languages into

  *--*--*  - various (possibly incompatible) extension languages,
   \ | /     e.g. oriented to particular programming paradigms.
     *     - a single, reasonably expressive common specification language
    /|\      (narrow-spectrum, but more expressive than e.g. Larch).
   / | \
  *--*--*  - various sub-languages, e.g. executable, unparametrized.

* LARCH DISCUSSION MEETING, 23 September, Soria Moria, Norway

To take full advantage of Jim Horning's presence at Soria Moria, and
somewhat refreshed after WADT'95 by a free afternoon, about 30 WADT
participants (about 20 of them already involved in the Common
Framework Initiative) gathered for an impromptu 90-minute discussion
focussed on Larch.  Having copies of the slides from Jim Horning's
invited talk "The Larch Shared Language: Some Open Problems" at
WADT'95 the previous day, we returned to some of the points that were
especially relevant for the Common Framework language.

It was particularly encouraging that this final meeting at Soria Moria
was so well-attended, and the mood was definitely one of general
optimism.  As Jim Horning commented: the participants in the Common
Framework Initiative have far greater collective expertise than is
usually the case when a group of persons sets out to develop a
language; moreover they seem willing to make compromises, and they are
not committed by some user community to perpetuate earlier design
choices.  Thus there should be a real chance of success!


The work items are as follows (the labels are the names of the
associated mailing lists):

- unif-lang: Language design, incl. abstract and concrete syntax,
  informal semantics, overall design of family of languages.  Some
  urgent topics: relation between parameterization, polymorphism,
  higher-order functions; partiality; survey of constructs in existing

- unif-sema: Semantics - formal, foundations.

- unif-tool: Tool support for specification and development.

- unif-meth: Methodology.  Some topics: behavioural specifications;
  relation between specifications and programs.

- unif-react: Reactive systems and states.

- unif-task: Administration/coordination of other work items.
  Organizing mailing lists, databases of resources, meetings.

Those who volunteered are as follows, the first one in each list being
the (initial) moderator for the corresponding mailing list AND
responsible for coordinating the corresponding work item:

- Language: Bernd Krieg-Brueckner; Didier Bert, Ole-Johan Dahl,
  Hans-Joerg Kreowski, Peter D. Mosses, Don Sannella, Andrzej Tarlecki,
  Michal Walicki. (8)

- Semantics: Don Sannella; Hans-Joerg Kreowski, Fernando Orejas,
  Andrzej Tarlecki, Eric Wagner. (5)

- Tools: Michel Bidoit; Didier Bert, Christine Choppy, Ole-Johan Dahl,
  Helene Kirchner, Bernd Krieg-Brueckner, Pierre Lescanne, 
  Peter D. Mosses, Peter Padawitz, Michal Walicki. (10)

- Methodology: Andrzej Tarlecki; Jose Fiadeiro, Marie-Claude Gaudel,
  Bernd Krieg-Brueckner, Tom Maibaum, Grant Malcolm, Gianna Reggio, 
  Don Sannella. (8)

- Reactive systems: Egidio Astesiano; Mohammed Bettaz, 
  Hans-Dieter Ehrich, Hartmut Ehrig, Jose Fiadeiro, Tom Maibaum, 
  Grant Malcolm, Olaf Owe, Peter Padawitz, Gianna Reggio, 
  Horst Reichel. (11)

- Coordination: Peter D. Mosses.

By the way, Don Sannella and Andrzej Tarlecki will be focussing on "in
the large" issues of language design and semantics.

N.B. All participants named above should SUBSCRIBE THEMSELVES to the
corresponding unif-* mailing lists, AND to unif-task!  (The mailing
list unif-task will remain very low-volume, and ALL participants are
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  For EACH work item above a succinct statement (max. 2000 chars,
  plain ASCII text) clarifying its AIMS and SCOPE is required.  

The moderators should send the statements to unif-task@daimi.aau.dk.
These will be collected and disseminated to all participants by the


Month   Objective
-----   ---------
Nov 95  Agreement on detailed statements of aims and means.
        Catalogue of constructs from existing specification languages.

Mar 96  Tentative proposal for constructs of the common specification

Sep 96  Firm proposal for constructs of the common specification language. 
        Tentative proposals for common framework sub-languages.
        Tentative proposals for methodology and tool support.
        Plan for development of common framework extension languages.


Dates  Month    Location     Event             Organizer        Topics
-----  -----    --------     -----             ---------        ------
17     Nov 95   Paris        FME-PC            Michel Bidoit    Language

18-19  Mar 96   Oxford       COMPASS/FME'96    Grant Malcolm    All

??     Jul 96   Munich       AMAST'96          ??               ??

17     Sep 96   Swansea      WG14.3/WADT'96    Karl Meinke      All


Further details about the common framework initiative, including
information about how to participate, will be made available on WWW
at URL:


\|/  Peter D. Mosses  <pdmosses@brics.aau.dk>
CFI  Coordinator, Common Framework Initiative
/|\  WWW http://www.daimi.aau.dk/~pdm/Common/