[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: XML Schemas: Best Practices
Right. On the other hand, the purpose of a registry is to make an association and that is also what a catalog does. I guess it depends on how sure one wants to be that the Thing Pointed At is the The Thing, and where the decision is made. The SSN is good: 1. As long as you are in the US. Venue authority makes a difference. SSNs are worthless outside the system that is the US. 2. As long as it is legal for you to use the SSN. The rules declared by the venue authority make a difference. SSNs can only be used if the system says you can use them. The point is that there is not a universal semantic or even if there is, you don't need that to solve the engineering problems for communication in noisy and noiseless channels. Shannon makes it clear that you don't want to go down that rathole. You want to talk in terms of *systems* that have means to get candididates and rules to choose among sets of equal possibilities. If you can do that, noise isn't a problem. You do want to know whether the system is closed or not (can it modify an environment and therefore produce a sideeffect introducing uncertainty - who is shaking the chads?, aka, the superstition problem when a filter introduces a belief system). A 404 is one answer as long as you can live with that. For some missions, you can't. Quality of service is negotiated as part of procuring a service and comes with terms and conditions. Known services can play tit-for-tat (renegotiate on default of service). TimBLs wet dream is that computers can do all of this automatically. Heck, we can't even be sure we got an honest ballot count here and we have a lot of computers. Problem is, we also have a lot of lawyers shaking chads. Systems that resolve critical decisions must have the granularity of signal to make the decision regardless of the noise and that is a "speed is money, how fast can you afford" dilemma. The criticality of the decision has to be known to establish the Ts&Cs among which will be traceability to enable you to establish culpability. The reliability of the signal (dimples) is what you build in the filters for. Len http://www.mp3.com/LenBullard Ekam sat.h, Vipraah bahudhaa vadanti. Daamyata. Datta. Dayadhvam.h -----Original Message----- From: Thomas B. Passin [mailto:tpassin@h...] Sent: Friday, December 01, 2000 11:44 AM To: xml-dev@l... Subject: Re: XML Schemas: Best Practices Len Bullard said - > Chase that thought you are > having a bit further in light of namespaces being > a signature for an interface. Then ask yourself if > you need or want that given that regardless of the > spec, the use of the URN/URL means to too many, a > location, not an authoritative owner of a domain. > That's why I advocate that actual namespaces ought to be URIs that are clearly not URLs. That would discourage people from trying to treat them as if they were. Especially in examples. So what if there's no registry guaranteeing uniqueness and permanence? There isn't for urls either, but that's not stopping anyone. To me, namespaces are something like US Social Security numbers. If I say that John Smith owns such-and-such a house, well, there are many John Smiths. If I say that when I say "John Smith", I mean the person with a ss number of 123-45-6789, that makes it unique. I don't expect or need other information to be coded into the ss number. Cheers, Tom P
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