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Re: URI schemes and IRI deployment

From: Ted Hardie <hardie@qualcomm.com>
Date: Tue, 29 Jun 2004 08:33:41 -0700
Message-Id: <p06110401bd0739ec9b29@[]>
To: Martin Duerst <duerst@w3.org>, "Williams, Stuart" <skw@hp.com>
Cc: public-iri@w3.org

This way of describing it concerns me, and I believe we
need to be very, very careful about saying "IRI scheme".

The IRI spec is defined such that any URI should be
representable as an IRI.  That does not mean that the
URI schemes themselves are capable of using IRIs,
nor that any protocol that currently uses URIs will understand
IRIs in those protocol slots.  It simply means that a
common, Internationalized presentation layer can be used
to represent the URIs.

There are systems out there that may be able to use IRIs
natively as identifiers, but that it is, I understand, in
cases like the XML "AnyURI"(sic) where the actual use
is to provide an identifier for which equality will be
checked character by character.   But this use
is not the same as the URI protocol processing,
and we should not conflate the two.


At 10:31 PM +0900 6/29/04, Martin Duerst wrote:
>Hello Stuart,
>Just a quick answer, because I'm traveling.
>At 11:56 04/06/29 +0100, Williams, Stuart wrote:
>>I'd like to understand expectations wrt to IANA registered URI schemes
>>following adoption of the IRI spec as an RFC and during deplyment of IRIs.
>>Do they 'instantly' become IRI schemes too?
>Yes, all of them in the sense that every URI is an IRI, at least.
>And most of them to the extent that they allow %-encoding and either
>require (e.g. urn, imap,...) or allow (e.g. http) the %-encoding
>to be based on UTF-8.
>>Will they require maintenance to allow the use of the expanded character set
>>allowed by the generic IRI syntax?
>Some of them will. The most prominent example: mailto:, which is
>very restrictive in where it allows %-encoding, if at all.
>>The IRI spec gives a generic syntax that allows a broader range of
>>characters to be used identifiers, but each currently registered scheme is
>>written from a URI perspective with the potential to narrow rather than
>>broaden the range characters used in an identifier from those permissablein
>>the URI spec.
>>The IRI spec. has section on upgrade strategy (7.8) which speaks of
>>upgrading of applications to handle IRI, but it does not appear to say
>>anything about upgrading of URI scheme registrations.
>What URI schemes might need upgrade or not can be deduced from
>the exact definition of what's an IRI, which explicitly requires
>that the result of the IRI->URI conversion has to be a legal URI.
>>The identifier http://www.w3.org/People/dÅ@st
>[sorry, my Japanese mailer will have garbled that]
>>may be admissable under the
>>generic IRI syntax, but is it a valid HTTP scheme IRI? And if so... what
>>specification makes it admissable as an HTTP scheme IRI?
>The IRI spec. If you take the above, and convert it to an URI,
>you will get http://www.w3.org/People/d%C3%BCrst. The HTTP URI
>spec says that this is a legal URI, so the one above is a legal IRI.
>In this case, it's not only legal, it's actually dereferencable,
>although the content at that location isn't terribly up to date,
>and the exact URI would be http://www.w3.org/People/D%C3%BCrst,
>but the server takes care of the casing issue.
>You will also observe that if you put the URI in the address bar
>in Opera, you'll get back the IRI. Other browsers may do something
>similar, or may at least allow you to put in the IRI and get
>to the actual page. (you have to be careful in the above example
>because I also put in some redirects, e.g. for
>http://www.w3.org/People/d%FCrst, the Latin-1-encoded version,
>but you'll see when that happens because the redirects are
>explicitly taking time.
>>Simply, my question is... what is the transition plan for scheme
>>registrations wrt to IRI deployment?
>For many if not most, there is no need for a plan. For some,
>such as http, it's mostly an issue of how people set up their
>servers. For some, such as mailto:, some work may be appropriate,
>but in that specific case, there have been quite a few discussions
>about weather and how to internationalize the left hand side of an
>email address, and that discussion hasn't yet been conclusive.
>It seemed better to wait to see where that would lead before
>upgrading mailto:.
>For newly created URIs, if they follow the guidelines for new
>URI schemes, they'll work with IRIs automatically.
>>Apologies if you have answered this before... I have looked, but did not
>>find anything relevant.
>In the IRI spec, please look at 'applicability' very early on,
>and then at the prose in the sections on syntax and on IRI->URI
>mapping. There is no such thing as e.g. a 'catalog of schemes
>that need upgrading', because after all, the IRI draft is a
>generic document.
>Regards,    Martin.
Received on Tuesday, 29 June 2004 11:34:17 UTC

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