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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: ??? (was RE: A simple guy with a simple problem)
 Failover is a good practice. Spreading redundant operations among different agencies is a good practice. No one still in business commits 99.99% 24/7. They try for it. It is an exercise in gently and diplomatically explaining to the customer that all due diligence is applied all the time to making the system as robust as possible. Then implement and test, and field and test. To stay in business, *read* the requirements carefully and *answer* truthfully and even more carefully. Pet the people who do your proposal work; they keep you away from bad business practices. Now take a look at schema and ask: who is the customer? What did they ask for? What can they afford? What can really be built for that cost? What would you propose given all of that? I think some may be surprised to find that XML Schemas are emminently affordable if implemented in common code for what they are intended to do. In fact, I'm not sure XML as a common transport for more than "doodads" is affordable without them. Cost is more than the cost to write and test the code. Lifecycle is more complicated than that. Common code, as Tim mentions, is key to reliability. So are common specs because they are how we get common code. I'm not sure about the semantic web. It may be something that takes a long time to realize a profit. Len http://www.mp3.com/LenBullard Ekam sat.h, Vipraah bahudhaa vadanti. Daamyata. Datta. Dayadhvam.h -----Original Message----- From: John Cowan [mailto:cowan@m...] Sent: Thursday, March 15, 2001 7:25 AM To: Tim Bray Cc: xml-dev@l... Subject: Re: ??? (was RE: A simple guy with a simple problem) Tim Bray scripsit: > >30 seconds of downtime per year??? > >Presumably you write in assembly language > > Bad, fragile software engineering practice In general, yes. But are you willing to bet lives that there won't be a bug somewhere in the compiler or support libraries that surfaces one fine day? Remember, if it takes you an hour to find it, that's your whole downtime available until 2121. > >on the bare metal of mil-spec > >hardware, > > in the computing space, typically less robust & reliable than > commercial off the shelf stuff with redundancy Maybe true by now, "milspec" probably doesn't mean what it once did. But consider how long you have to recover from various disasters: Multistate power outages happen about every 30 years. You have 15 minutes to recover from them, assuming no other problems. Catastrophic fires, the kind that leave a city mostly ruined, happen about every 100 years in the U.S., more often elsewhere. You have less than an hour to reroute all communications through a network jammed with emergency operations and people trying to find out about their friends and relations. Catastrophic wars, the kind that leave your essential support personnel dead (or in the army and unavailable), happen every 50-100 years. You have less than an hour to relocate all operations to an unaffected country, assuming you can find one. You don't catch me promising 30 sec/yr downtime for anything. > Depending on well-debugged existing code/gear is one of the > the best practices in achieving high reliability. -T High reliability, yes. Extremely high reliability, the kind we are talking about here, no. -- John Cowan cowan@c... One art/there is/no less/no more/All things/to do/with sparks/galore --Douglas Hofstadter ------------------------------------------------------------------ The xml-dev list is sponsored by XML.org, an initiative of OASIS <http://www.oasis-open.org> The list archives are at http://lists.xml.org/archives/xml-dev/ To unsubscribe from this elist send a message with the single word "unsubscribe" in the body to: xml-dev-request@l... 
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