- From: Julian Reschke <julian.reschke@gmx.de>
- Date: Wed, 21 Nov 2001 11:12:15 +0100
- To: "Jim Whitehead" <ejw@cse.ucsc.edu>, <w3c-dist-auth@w3.org>, <uri@w3.org>
> From: w3c-dist-auth-request@w3.org > [mailto:w3c-dist-auth-request@w3.org]On Behalf Of Jim Whitehead > Sent: Wednesday, November 21, 2001 3:29 AM > To: w3c-dist-auth@w3.org; uri@w3.org > Subject: RE: RFC2518 (WebDAV) / RFC2396 (URI) inconsistency > > ... > > That is, the "dav:" URI scheme can be considered a member of the class of > non-hierarchical URIs described on page 12 of RFC 2396. In particular, it > was never the intent that just the string "dav:" would be > considered a full > URI. The string "dav:" is a URI scheme name, not a URI. The string "dav:" > plus a string matching the production "opaque_part" is a URI. Correct so far. > * WebDAV marshals "dav:" URIs that are the name of XML elements as a > {namespace} + {opaque_part} pair. So, for example, "dav:creationdate" is > <D:creationdate xmlns:D="dav:">. RFC2518 says *nothing* about URIs in the DAV: URI scheme. RFC2518 itself never says that an element name or a property "has" a URI. <D:creationdate xmlns:D="dav:"> must be read according to the specs that exist, and this means: an XML element with name "D:creationdate", local name "creationdate" and namespace name "dav:". BTW: this should have been "DAV:", right? If you claim that any element or property in WebDAV has a URI, you'd have to answer: - do WebDAV element names and properties share the same namespace? - what are the URIs (identifiers!!!) for: <cd xmlns="http://a/b/" /> and <d xmlns="http://a/b/c" />? > * The XML Namespace recommendation requires that the namespace > identifier be > a URI. Correct. > * Since "dav:" scheme URIs are members of the class of non-hierarchical > URIs, the only constant part is the URI scheme name itself, > "dav:". From the > definition of non-hierarchical URIs given in RFC 2396, ALL > non-hierarchical > URIs will share this quality. Since "dav:" is the only constant > part, it is > the only part of a "dav:" scheme URI suitable for use as the namespace > identifier. Why would that be? "DAV:deltaV" and "mailto:julian.reschke@gmx.de" are perfectly valid URIs and therefore useable as namespace names. > To summarize: > * The "dav:" URI scheme is perfectly legal according to RFC 2396. Yes. > Therefore, > no change is needed to RFC 2396. > * It is only the use of the "dav:" URI scheme name as an namespace > identifier that is violating any specification. Either RFC 2518 or the XML > Namespaces specification could be changed to rectify this. Guess what will be asked to be changed then :-) > In my opinion, it is natural to want to use the URI scheme name as the XML > namespace identifier. That is: > > <D:getcontentlength xmlns:D="DAV:"> > > is more natural than: > > <D:getcontentlength xmlns:D="http://www.webdav.org/"> It's shorter, but it's invalid (according to the XML NS rec), while the other one is perfectly valid. > Not to mention that it uses fewer bytes on the wire (not a huge > consideration these days, but those bytes add up over millions of daily > users). OK, let's tell the W3C to use "xhtml:" instead of "http://www.w3.org/1999/xhtml". > As a result, I recommend that the XML namespace recommendation be modified > to allow the use of just the URI scheme name as a namespace identifier, > perhaps limited to just members of the set of non-hierarchical URIs. It > seems clear to me that the XML namespace recommendation was written with > only the class of hierarchical URIs in mind, and as a result it's not too > surprising that a glitch arose in the first use with > non-hierarchical URIs. I doubt that anybody is going to touch XMLNS, but I'd still be interested how you come to this conclusion. The issue is not with non-hierarchical URIs, the issue is that RFC2518 is using "DAV:" as URI where it shouldn't. > Based on Julian's experience, and our experience with multiple WebDAV > implementations, accepting a URI scheme name as a namespace > identifier would > codify existing, interoperable, practice. *Lack* of interoperability with James Clark's code in JING exactly is the reason why we have this discussion. I think we should thank him for actually *using* the grammer in RFC2396 for validation, so this was finally uncovered.
Received on Wednesday, 21 November 2001 05:12:46 UTC