RE: URN Madness (was re: Overloaded URIs must GO!)
Hi David, David said: That's what I meant by "the URN schemes are not yet defined" (or whatever my wording was). In other words, URNs are not yet safe to use for XML Namespace URIs outside of the IETF (x-* URN namespaces are not guaranteed unique), but they may be soon. For now, we have to keep using URLs. Didier says: Here is the simple mechanism the W3C can do (And the sentence "outside of IETF" has no real meaning unless you mean that outside W3c there is nothing ;-) Scenario: URN is used to obtain a document. a) W3C reserve a namespace and send to IANA a URN registration paper. b) install a DNS server and enter the right records to resolve URNs into URLs (for each "official schemas") c) All parsers in need to get a document about a particular name space (like for instance a schema or a DTD) could then use the DNS protocol (and of course connect to the W3C server - or the backup server) d) Then, all the URNs would be resolved as URLs and the document downloaded with the right protocol So, there is maybe something I am missing. Why is URNs not safe for XML name spaces? If we use URLs is it simply to fill an empty space :-) or is it because it points to a place where a document is stored? If it is because it points to a location where a document is stored. A URL has the disadvantage that if you change the location of this document, all documents having a reference to this location are no pointing to the right location and could not practically be validated. Do we sell XML as having a longer shelf life than other formats? If yes, URLs are dangerous because they are tightly connected to the location (the name itself tells it all a U_niversal R_esource **L_ocation**). A URN gives you location independence, the document may be moved to a different place and the URN will be still valid. You'll just have to change the DNS record but won't have to change every single document in the field. Have you read carefully not the drafts _but_ the **RFC 2141**. If yes, after this reading, what is the problem you have with URNs and what is your argument about the location problem inherent to URLs. What if we move the document form one location -URL- to a new one? Note: The official name space documentation may not necessarily be W3 but a registry somewhere so that people could register their official name space documentation (i.e for example a schema or DTD).You'll also resolve other problems with such registry like for instance e-commerce. regards Didier PH Martin mailto:martind@n... http://www.netfolder.com xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ and on CD-ROM/ISBN 981-02-3594-1 To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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