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Re: IRI length limits (ticket #37 => #46, #47, #48)

From: Ted Hardie <ted.ietf@gmail.com>
Date: Tue, 28 Sep 2010 11:18:02 -0700
Message-ID: <AANLkTimfi=OYhquMtRbDjjzVpu=fiZvjaMMmtGezsR+6@mail.gmail.com>
To: Martin J. Dürst <duerst@it.aoyama.ac.jp>
Cc: "public-iri@w3.org" <public-iri@w3.org>
Hi Martin,

Some comments below.

On Tue, Sep 28, 2010 at 3:08 AM, "Martin J. Dürst"
<duerst@it.aoyama.ac.jp> wrote:
> Ticket #37 raises the issue of length limits for domain names (and
> implicitly, for IRIs in general).
> Among chairs and editors, we came to the conclusion that there are at least
> three aspects:
> 1) normative (i.e., hard and fast) length limits
> 2) practical length limits where advice to implementers may be appropriate
> 3) the question of whether schemes can set specific length limits
> I have therefore split this issue into three new issues as below. Comments
> are appreciated.
> #46: Normative length limits
> (http://trac.tools.ietf.org/wg/iri/trac/ticket/46)
>   I personally propose that we close this issue without action, because
>   I was unable to find any such limits in RFC 3986 (URIs), and do not
>   think such limits make any sense.

It's not clear to me whether you are closing the normative  issue for
domain names or for IRIs in general. RFC 1034 has some normative limits;
e.g. a label is between 0 and 63 octets in length.  I agree that we should
not introduce new limits, but reference to the ones which do exist still
seem to me necessary.

> #47: Practical length limits
> (http://trac.tools.ietf.org/wg/iri/trac/ticket/47)
>   I personally think that the main advice we have to give implementers
>   is that they may have to increase length limits in some cases.
> #48: Can schemes set specific length limits? Should RFC4395bis say something
> about this?
>   My current thinking is that obviously, schemes can set some length
>   limits, because they can define syntax restrictions. Also, they
>   could do that in silly, counterproductive ways. But this all seems
>   to be rather obvious, so I personally think that we may not need
>   to say anything on this topic.

I think it should be noted, probably in RFC 4395bis.  Some schemes
do not use the domain name system for the authority section, to take
one example, but might have similar restrictions on their equivalent
to "label length".    If you look at the draft I put forward a while
back p2p URI pointers (see
now expired), you'll see an overlay-pointer-uri.  That was generalized
sufficiently that there was no length limit, but I can easily imagine specific
schemes limited to the maximum production of the mechanism for producing
the node-id (commonly 128 bits).

It may be obvious to us, but I'd rather err on the side of noting the

> As a result of these new issues, I'm going to close issue #37.
> Regards,   Martin.
> --
> #-# Martin J. Dürst, Professor, Aoyama Gakuin University
> #-# http://www.sw.it.aoyama.ac.jp   mailto:duerst@it.aoyama.ac.jp
Received on Tuesday, 28 September 2010 18:18:41 UTC

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