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Re: Migration of HTTP to the use of IRIs [queryclarify-16]

From: Martin Duerst <duerst@w3.org>
Date: Fri, 27 Jun 2003 12:19:30 -0400
Message-Id: <>
To: "Chris Haynes" <chris@harvington.org.uk>, <public-iri@w3.org>

Hello Chris,

Many thanks for your comments on the IRI spec.

I have noted your issue as:

More explanations below.

At 23:21 03/06/26 +0100, Chris Haynes wrote:

>Dear Martin / Michel,
>I'm looking at draft-duerst-iri-04 from the viewpoint of a provider of
>web server technology. I'm trying to understand the likely migration
>path to the use of IRIs, and I'm concerned that there's a gap I don't
>see being filled.
>It may well be that filling the gap is outside the scope of your
>Internet Draft, but unless the gap is filled, I fear there may be a
>_long_ delay before IRIs are adopted where they are most needed.
>Your section 7.8, Upgrading Strategy, contains some useful thoughts /
>advice, which I have summarised to myself as "Don't put in an
>IRI-aware server until all the resources on the site(s) you serve are
>published in IRI".
>However that's not the problem that concerns me.
>I'm concerned about the encoding of HTTP GET query strings, typically
>carrying text inserted by a user into a browser's form.

You are right that section 7.8 does not address query strings,
and that it doesn't say so clearly, and that there is otherwise
not too much about how query strings are supposed to work.
I have noted this specific aspect of your mail as an issue,
and will try to update the draft accordingly.

>Assume below that "I" am the developer of a web server. (I'm not, but
>I advise someone who is).
>I want to support IRIs as soon as possible. I know that 'out there'
>are many different makes and releases of browsers; I have no control
>over them.
>As is well known, there is no mechanism in RFCs 2396 / 2616 for
>indicating the encoding associated with any %hh octet-triplets in


>Unless I've missed something, your draft implies that user agents
>(browsers) may perform IRI to URI conversion, so that 'my' server sees
>an RFC 2396-conformant URI.

Well, they actually have to do this conversion, because HTTP
does not allow anything else than an URI in the request.

>How do I know it is was originally an IRI and that I should apply the
>reverse conversions of your section 3.2 before extracting the query
>name-value pairs?

You don't. Equally well, you don't know whether the name/value
pairs were in iso-8859-1 (Latin-1), or shift-jis, or whatever.
HTTP does not help you there at all.

>The problem is not 'academic', the vast majority of browser requests
>received today which have %hh triplets used encodings other than
>UTF-8, and these will continue to arrive for the next 20-or-more

Well, for query parts, you actually have quite some control over
what encoding you get the query part back. Already since a few years,
browsers send back the query part in the encoding that they received
the page in. This works quite well. So if you want to have any
idea of what you get back from a browser, you have to know how
you send out your pages. And if you use UTF-8 for your pages,
then you get three main benefits when compared to other encodings:
- UTF-8 can handle the widest range of characters
- UTF-8 will bring your GET request in line with IRIs
- UTF-8 can be checked with very high reliability

For more information, please also see the Q&A page that we put up

>You may well answer that the way IRIs are to be applied is to be
>scheme-dependent; the problem/opportunity  is for the HTTP RFC2616++
>community to address.

Well, part of it could be addressed scheme-by-scheme. For example,
a new scheme could require that only UTF-8 be used in the query
part. It can also be addressed by other technologies, for example,
XForms, which requires the use of UTF-8 in the query part of GET
requests (see http://www.w3.org/TR/xforms/slice11.html#serialize-urlencode).

>I would feel *far* more comfortable if I knew that they were aware of
>this and if there were draft proposals visible on this list and being
>checked for feasibility and for 'compatibility' with your drafts.
>I've seen no evidence for this, and you don't appear to
>cross-reference any related HTTP activity in your draft.
>It is not beyond the bounds of possibility, for example, that the HTTP
>community might conclude that they cannot provide IRI support unless
>your RFC-to-be  includes some kind of marker or syntactic construction
>within "URIs which were converted from IRIs" which explicitly
>identifies them as such.
>In other words it might be found that all IRIs MUST be mapped into
>some character sequence which IS NOT a 'legal'  URI (by the current
>RFC2396), so that the receiver knows that the reverse process of your
>section 3.2 MUST be applied.

This would mean choosing a different escape convention.
We considered this years ago, but decided against it.
Using something that is illegal in an URI would not have
worked, and would still not work, with the current infra-

>There are other approaches the HTTP community could take, which
>_would_ be compatible with your current draft, (and I have my own
>candidate solution), but surely there should at least be some kind of
>'existence proof' or 'feasibility study' by which they agree that they
>_can_ work with your proposals before they are finalized?

I hope what I have explained above is enough of an 'existence proof'.

Please tell me if you don't think so.

Regards,    Martin.

>Without some kind of 'roadmap' for HTTP use of IRIs I don't see how
>anyone can pass final judgement on your draft.
>Please reassure me by telling me I'm an idiot for not knowing about
>XXX or not reading YYY.
>Chris Haynes
Received on Friday, 27 June 2003 12:29:18 UTC

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