Date: Sat, 25 Oct 1997 13:08:42 +0100 (MET) From: Dirk-Willem van Gulik <firstname.lastname@example.org> To: Dan Connolly <email@example.com> Cc: Leslie Daigle <firstname.lastname@example.org>, email@example.com, firstname.lastname@example.org, Subject: Re: [URN] Re: The UR* scheme registry, Citing URL/URI specs In-Reply-To: <34512536.6FB1@w3.org> Message-Id: <Pine.GSO.3.96.971025124202.7051Gemail@example.com> On Fri, 24 Oct 1997, Dan Connolly wrote: > Short version: > > Leslie Daigle wrote: > > > Syntax draft says "URIs are covered by other specs". > > > What other specs? > > > > RFC2141 > > Hmmm.... checking... > The term URI does not occur in RFC2141. > So that's no help. > 1630 ?! Hmm, Alhoug I might sail into dangerous groups, I've always felt that somewhere rough consensus suggest that in the big and happy UR-<alphabet-soup> group of things a 'URI' could kind of be seen as the thing that imposes constraints on all, i.e. RFC1630 (and I could see the need for some updating there). The various URL specs (for http, finger, ldap, z3950, handle-scheme, telnet, ftp, mailto, etc) should all just refine the 1630 definition; as does the URN definition 2141. Nicely enough, the 1994 written RFC 1630 says: URLs are listed here. The Uniform Resource Name (URN) debate attempts to define a name space (and presumably resolution protocols) for persistent object names. This area is not addressed by this document, which is written in order to document existing practice and provide a reference point for URL and URN discussions. And I would most certainly advocate to use it as such a reference point, and make the URN just one of those flavours URIs, and adhere to the same 'Universal Syntax'. Although I might be wrong, (and am most certainly wrong when it comes to some of the URLs currently in use) I would assert that the current URN (21441) syntax fits perfectly within the 1630 constraineds of its 'Universal Syntax'. If this is not the case we should fix it. > > One specific document you don't seem to have been aware of is the URN syntax > > standards-track RFC (RFC2141). > > I'm aware of it (I read some of the earlier drafts.) It specifies > a syntax where all the strings start with urn: . I got > the impression urn: would go in the list along with http: > and ftp: and all the rest in places like the IANA registry, > the Java APIs, the Address/Location field in browsers etc. > Not so? Syntax wise, I would guess that most people on this list would give a big yes, sematically of course it is a diffeernt issue. > > I won't speak directly to the issue of whether or not the W3C documents > > should refer to URIs or URLs, > I wish you would. Well, let me make a stab at this as well... jus to see if this would narrow down the discussion. I personally believe that the w3c documets should use the term URI when they refer to a universally applicable name which is to contain references to registered protocols, namespaces. When the documents refers to the location of the resource, as to be used to obtain the resource from the given localtion(s) with the given protocol, i.e.without any level of indirection outside the name (though possibly within the protocol) then the more preciese term URL should be used. If however the application described in the w3c document needs to be very explicit about the location independent resource idenfification it would be bettter to use the URN word. Quite naturally there is a blurr between a URNs and URLs, in particular a carefully choosen URL might fullfill most, if not all, _functional_ requirements of a URN; and a poorly chosen URN space can end up being as messy and location dependent as URLs. So as a usefull guideline, I would look at the functional requirements in the w3c drafts, what is it that one expects from that information element reffered to, and when in doubt use the 'URI' word. Though it would surpize if that is that often needed, when you get to the gritty details of actually coding it, meeting the functional requirements of URNs and using them that way makes them very, very different from URL's and it is very obvious which is which, and why you need both. > > URLs. URNs are discussed in RFC2141. The syntaxes are intended to be > > compatible. > I keep hearing that, but I look at the standards-track documents, > and I don't see it in black-and-white. So would it help if there was an updated 1630 which talked only about URI syntax, and and updated 2141 which only points to the URI syntax with a refinement; and likewise for the URL definitions, etc. etc, I would still like to keep 1630, as it gives a lot of 'architecture' information which should not be lost. i.e. urI Syntax 'scheme:path' escaping .urL = urI + meaning of the hash, ?, etc, relative stuff, protcol name registry ..HTTP = urL + naming segments, query string, etc ..FTP = urL + way to encode username passwd, etc, etc .urN = urI + naming schemes, etc. as most is perceived to be defined this way anyway, the split up over the defining documents is jsut a bit awkward. Just my 200 lire's worth, Dw.