From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-0.4 required=5.0 tests=AC_FROM_MANY_DOTS,BAYES_00 autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,c617ae447ca32f2f X-Google-Attributes: gid103376,public X-Google-Thread: ff121,3ae3fa74ecb04ab8 X-Google-Attributes: gidff121,public X-Google-ArrivalTime: 2002-04-01 18:04:12 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!newsfeeds.belnet.be!news.belnet.be!newsfeed.wirehub.nl!psiuk-p2!psiuk-p3!uknet!psiuk-n!news.pace.co.uk!nh.pace.co.uk!not-for-mail From: "Marin David Condic" Newsgroups: comp.software.extreme-programming,comp.lang.ada Subject: Re: Ariane Failure Date: Mon, 1 Apr 2002 10:08:50 -0500 Organization: Posted on a server owned by Pace Micro Technology plc Message-ID: References: <3CA4B8E5.72909C9B@adaworks.com> NNTP-Posting-Host: dhcp-200-133.miami.pace.co.uk X-Trace: nh.pace.co.uk 1017673731 6900 136.170.200.133 (1 Apr 2002 15:08:51 GMT) X-Complaints-To: newsmaster@news.cam.pace.co.uk NNTP-Posting-Date: 1 Apr 2002 15:08:51 GMT X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 Xref: archiver1.google.com comp.software.extreme-programming:12825 comp.lang.ada:21965 Date: 2002-04-01T15:08:51+00:00 List-Id: I beg to differ on the "Bad Directions" part. Note that the software in question was designed for the Ariane IV which had a different flight profile. The FDA thinking for the module in question went sort of like this: "Any number that shows up here big enough to generate a hardware overflow interrupt has got to be so far out of the flight profile that it would most likely indicate a bad sensor. The accommodation for this failure should be to transfer control to the other side where we might still have a good sensor..." This logic worked fine in Ariane 4 and would likely have detected a sensor failure and accommodated it appropriately. In my mind, that sounded a lot like "Good Directions" :-) The problem arose when the assumption was made that software that was designed for Ariane 4 and that worked just fine in that environment was therefore fit to fly Ariane 5 WITHOUT being tested and validated against the Ariane 5 flight profile. That's a pretty basic and fundamental error that goes well outside the realm of control of a programming language or methodology. MDC -- Marin David Condic Senior Software Engineer Pace Micro Technology Americas www.pacemicro.com Enabling the digital revolution e-Mail: marin.condic@pacemicro.com "Richard Riehle" wrote in message news:3CA4B8E5.72909C9B@adaworks.com... > > The problem with Ariane V begins with Systems Engineering management. > The decisions about what to do when an exception occurs were wrong, and > not tested. Although Design By Contract might have helped, I doubt that > Eiffel would have been appropriate because of other issues related to > Eiffel. I like Eiffel, but don't consider it appropriate for a project such > as Ariane V. The SPARK approach to Design By Contract (they don't > call it that, but that is what it is) could have worked well, especially > since it was programmed in Ada. By the way, the Ada code worked as > it was directed to work, but it was given bad directions. >