[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: Dereferencing Namespace URIs considered harmful
I am aware that there has been much discussion on this topic, and perhaps more discussion could be construed as flogging a dead horse. If someone has already covered my particular point of view, I apologize and recommend ignoring this email. I am a new member of this listserv and just couldn't afford the time to read through all the archives. I feel that, in considering the possibility of dereferencing Namespace URIs, those folks who support this position are perhaps not considering the primary rationale behind a namespace URI, namely, it's one part of a two-part name (to use James Clarke's notation): {namespaceURI}localName As I understand the situation, the URI format was chosen because of its somewhat globally-unique nature, and not because of any specific properties of a real-world URI. A GUID or UUID could equally-well have been chosen (albeit with a leading underscore to comply with XML naming rules). Someone could have (and probably did) suggest having a namespace based on UUIDs: _625caa20-6190-11d4-896800b0d044f4de:localName Not very readable, but certainly functionally identical to a namespace using URIs. This two-part name is certainly globally unique, and due to the method of generating UUIDs, no special central registry need be kept to avoid name clashes. But that.'s not the point, really. I feel that dereferencing part of a two-part name because of its accidental resemblance to something that exists outside of the context of that name is tantamount to the old mistake of "overloading" part of a database key to mean something else. As an example, I am reminded of a telephone company that assigned special meaning to the high-order digits of a subscriber's account number, on the assumption that there would never be that many subscribers. Of course, the fateful day arrived where the number of subscribers reached critical mass, and suddenly people found themselves getting huge discounts on their phone bills, simply because their account numbers had fallen into the previously reserved range. Fixing the problem proved very troublesome. Although the Namespace URI issue is not quite the same kind of problem, I believe the general rule of separation of concerns applies here, and that namespace URIs should be treated the same way as UUIDs: a unique identifier that has no special meaning outside of the mnemonic value afforded to humans. Failing to do this could have negative ramifications that are hard to predict. On the other hand, steering clear of this will guarantee a lack of negative consequences (at least, connected to this issue). Regards, Edwin Fine CommerceQuest, Inc.
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