- From: Larry Masinter <LMM@acm.org>
- Date: Wed, 9 Apr 2003 11:36:39 -0700
- To: "'Tim Bray'" <tbray@textuality.com>
- Cc: "'Paul Cotton'" <pcotton@microsoft.com>, <www-tag@w3.org>, "'Paul Grosso'" <pgrosso@arbortext.com>, <roy.fielding@day.com>
# Since *nobody* can *ever* commit to maintaining anything in perpetuity, # given that in the short run we're all dead and in the long run there's # the 2nd law of thermodynamics, do you thus feel that all URLs should # abandoned forthwith in favor of URNs? A good reductio ad absurdum, but not what I'm advocating. I believe that some people might judge that a URN meets their needs better than an HTTP URL, when selecting a namespace name, and that the W3C web architecture has no need to strongly prefer one over another. Part of the review criteria for registering a URN namespace is the evaluation of the registrar's claims of "permanence". In that sense, there's at least some judgment about permanence of URNs, and an attempt to insure it. Some URN namespace owners might be willing to allocate URNs for resources they don't control, didn't author, or make no claims of authorship about, even while providing some assurance of permanence, while some namespace authors might have difficulty obtaining a similar promise for http URLs, purl.org notwithstanding. Here's a different kind of argument: At this level, "http" and "urn" are just URI schemes, and there is no strong architectural reason to prefer one over the other. Building "http" into the web architecture deeply is bad design; it makes it unnecessarily fragile. And if you're going to allow schemes other than "http", then you might as well allow "urn". # The trouble is, we seem to lack consensus; in particular on the claim # that URNs have a superior quality of "permanence" in some sense. Our # interchange right here is evidence of that. I'm not claiming that "all URNs are more permanent than all URLs", surely that is false. I'm not claiming that "some URNs are more permanent than all URLs", since, at some level, a URN is a kind of a URL. In fact, I don't even want to try to make a claim about permanence, but rather one about "belief about permanence" and the architectural principle of not disallowing workable choices unnecessarily. Personally, I think one advantage of "urn" over "http" might be for namespace assigners would be that there's no need to put up web space or get any web traffic. Let me turn this around: why do you think it's important to stamp out the practice of using "urn" URIs for namespace names? Larry -- http://larry.masinter.net
Received on Wednesday, 9 April 2003 14:36:52 UTC