- From: Michael Mealling <michael@bailey.dscga.com>
- Date: Mon, 5 Jun 2000 16:09:23 -0400
- To: keshlam@us.ibm.com
- Cc: John Cowan <jcowan@reutershealth.com>, "xml-uri@w3.org" <xml-uri@w3.org>
On Mon, Jun 05, 2000 at 04:11:53PM -0400, keshlam@us.ibm.com wrote: > >After absolutizing, you simply have to chop off further processing and say > >"if not equal now, then not equal at all", neglecting things like DNS > >case-blindness, symbolic links, http: and ftp: aliases, and so on. > > That can be done, certainly, but it's not really the URI semantics. URIs > only define strong equality; they don't define strong inequality; they can > tell you that "http://www.ibm.com" equals itself, but if you compare it > with "http://198.133.16.99" they say only "we don't know". > > Yes, browsers operate on this weak-inequality mode when they change the > color of a link to indicate it has been visited. But that's entirely a > convenience feature; a false negative is relatively harmless. (The user > visits the page again when they didn't have to, says "oops", and backs > out.) If you're using URI recognizability to drive machine processing, the > consequences get more expensive -- consider a search engine which must now > waste time exploring redundant links. And if you're using it to drive > namespace-aware document processing, where the essential goal is to be able > to recognize the namespace/localname combination in order to get a yes/no > "is this one I need to process" test, "I don't know" is not a useful > response. > > We can extend those semantics for purposes of namespace identity, and say > "if we aren't certain it's equal, namespaces must treat it as unequal." But > this is arguably a violation of the architectural assumptions behind URIs. > And since the argument for absolutizing is an architectural one... Actually it isn't. I know it isn't in 2396 but the assumption has always been that if you don't know their equal then they aren't equal. -MM -- -------------------------------------------------------------------------------- Michael Mealling | Vote Libertarian! | www.rwhois.net/michael Sr. Research Engineer | www.ga.lp.org/gwinnett | ICQ#: 14198821 Network Solutions | www.lp.org | michaelm@netsol.com
Received on Monday, 5 June 2000 16:20:51 UTC