EWICS: object-oriented-subgroup

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1. Introduction

The OOSS subgroup was initiated in 2008 at the spring meeting of EWICS TC7. By using its members’ knowledge and experience, the OOSS subgroup focuses on the task to work out and publish an EWICS TC7 position paper about possibilities and limitations of the use of object oriented software in safety systems. Up to now members of the group from the following countries have contributed: Austria, Denmark, Germany, Great Britain, Italy, Netherlands, Norway, Switzerland, Turkey and USA. The list of corresponding members includes additionally experts from: Chile, France, Poland, Romania and Sweden. The group meets four times per year.

2. Problem Statement

The use of object oriented software in safety systems is not generally accepted in various application areas. While some companies are quite progressive here, others as well as some standards are restrictive concerning the use of OO techniques. During the recent maintenance procedure of IEC 61508, e.g., contradicting opinions were raised.

Restrictions and precautions are quite justified in the field of safety systems. On the other hand the use of modern IT, tools, programming languages and related techniques cannot be withheld for ever from the safety area.

So guidance is needed. EWICS TC7 has formed a group for discussion and for developing some guidelines on the use of object oriented software in safety systems: what restrictions might apply, which rules should be followed, and what is to do during the certification and approval procedure. Issues discussed and worked on are, among others:
• Rules for conventional software that still apply to OO,
• OO Analysis of automation systems for safety and resulting specification,
• Architecture of OO safety software,
• Threading,
• Dynamic binding, overriding and dynamic objects,
• Tools,
• Use of design patterns,
• Coding,
• Specific requirements for verification, in particular testing,
• Modification.

The objective of the Subgroup is to publish

”Guidelines for the use of Object Oriented Software in Safety Systems”

as an EWICS TC7 Position Paper and as an input to international standardisation. The Guideline will be language independent.

3. Activities and Progress to Date

So far experiences gained by its members and from the literature have been considered; most of the publications originate from avionics. Agreement has been reached on:
• the use of the classical design patterns;
• including a chapter about on the spot required verification efforts after the related main chapter and to have a general verification and validation chapter at the end;
• expressing rules mainly in table form.

The work on
• Object-Oriented Analysis, Specification, OO Architecture, Dynamic Objects, and on as related Verification efforts has made good progress.
• In particular the work on Terminology and OO Design took much time
• Currently the discussion focuses on Terminology, harmonisation of the assembled rules and examples of applications. Keeping the existing draft free from contradictions turns out to be time consuming.

4. Contacts and Membership

The OOSS Subgroup, as all EWICS subgroups, is an open group and welcomes participation. Members of the group profit from the information exchange for their daily work. There are a number of ways you could become involved:
• By reviewing of the work as it matures.
• By providing material on particular problems, examples and practices related to the aim of the venture.
• By attending meetings and contributing to the work of the group by discussion.

For more information please visit www.ewics.org or contact:

Wolfgang Ehrenberger (Convenor)
University of Applied Sciences
Angewandte Informatik
36039 Fulda, Germany
phone: +49 661 9640 325
fax: +49 661 9640 349
E-mail: wolfgang.ehrenberger@informatik.hs-fulda.de

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