[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: [offtopic] The Airplane Example (was Re: Streami
Software copes with inputs by classifying them. Classification fails when an unidentifiable event enters the pipeline. Users of classifiers fail when they misidentify an event. Between the mistakes the user can make and the events that are not identifiable by the original design are many of the failures of software engineering. Issac Newton was an alchemist and a mathematician. Albert Einstein was a patent clerk and a mathematician. Note they were considered 'competent' scientists. BTW: control system failures in fly-by-wire systems predate Cali. The F-111A had a nasty habit when its terrain following software actions contradicted the reflexes of the pilot. The software and the wetware have to cooperate in any real time system both at the level of inputs and the acts of recognition. Because these are dynamic interactions both in combinatorics and in the capability to produce unknown-unknowns (new events that are beyond the range of modeling), the safety margins are statistical, not real. For that reason, experience is prized. Indemnity in design is about making mistakes with knowns, not unknowns. Still, some statements made in this thread about software engineering are pertinent particularly if one changes the title to 'computer scientist' and asks the question, what of this IS *science*? Try to sort out the terminology of a profession that has consistently reinvented its concepts inconsistently for over fifty years. If the next century is to produce something really innovative, it may be a consistent and maintainable science of applied computer technology. Or not. 0 or 1. Choose. You have a chance of getting that right. len -----Original Message----- From: Michael Champion [mailto:michaelc.champion@g...] Sent: Saturday, January 01, 2005 11:20 AM To: XML Developers List Subject: Re: [offtopic] The Airplane Example (was Re: Streaming XML) On Sat, 01 Jan 2005 14:57:05 +0000, Bill de hOra <bill.dehora@p...> wrote: > On the other hand trying to delineate what's engineering and what's > alchemy in a software sense is no bad thing I'm not sure I follow. To me, it's not clear what is alchemy and what is engineering and what is computer science in the real world. The Cali plane crash example seems to illustrate that -- the on-board software worked as designed, and the design was rational, it just made assumptions about a) the distribution of navigation beacons and b) the attention to detail on the part of the pilots that turned out to be over-optimistic. Is this engineering or alchemy? I'm not sure. Benjamin Franz seems to think that best practices are clear and a good process could have caught these unrealistic assumptions in advance. Maybe, but I have a feeling that "best practice" is more of a collection of hard lessons learned from investigating disasters, and anticipating new flaws at the design phase is more in the realm of alchemy than engineering. But maybe this is just a matter of using slippery and value laden words in inconsistent ways, not real disagreement. But remember that Newton was an alchemist, and Kepler was an astrologer :-) So, it probably is worth trying to delineate engineering from alchemy, but I expect the line to be pretty fuzzy. ----------------------------------------------------------------- The xml-dev list is sponsored by XML.org <http://www.xml.org>, an initiative of OASIS <http://www.oasis-open.org> The list archives are at http://lists.xml.org/archives/xml-dev/ To subscribe or unsubscribe from this list use the subscription manager: <http://www.oasis-open.org/mlmanage/index.php>
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