Re: [urn] gbs Name space identifier

worley@ariadne.com (Dale R. Worley) Tue, 22 October 2019 02:12 UTC

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From: worley@ariadne.com (Dale R. Worley)
To: Philip R Brenan <philiprbrenan@gmail.com>
Cc: juha.hakala@helsinki.fi, urn@ietf.org, lars.svensson@web.de
In-Reply-To: <CALhwFR=LKzGK2So6S1LfHroFLFi0H12WevEzNJC_qTMsZtr0+w@mail.gmail.com> (philiprbrenan@gmail.com)
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Date: Mon, 21 Oct 2019 22:12:20 -0400
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Subject: Re: [urn] gbs Name space identifier
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Philip R Brenan <philiprbrenan@gmail.com> writes:
> May I therefore urge that MD5 is an appropriate choice for now and that
> adoption of this particular proposal should not be made dependent on finding
> a perfect digest?

I have no complaint against the use of MD5.  If I commeneted on it, I
expect that the cause was that some part of the text was unclear or
inexact.

> May I propose that the need to access the content of a URL or URN to fully
> validate the URI is a common feature of all name spaces as evinced by the
> existence of HTTP code 404 and thus should not, in of itself, impede the
> adoption of this particular proposal?

I have no concern about whether the URN can be validated.  But it's
common when a "validation" procedure is given, that it does not require
access to the designated resource itself.  So it is useful to the reader
to note that this procedure involves checking the URN against the
resource.

> On Inter-operability, following your suggestion, I have clarified why
> case is often immaterial in anticipated operations on this name space
> as follows:
>
>    For many computations, the case of the letters in the URN is immaterial and
>    can be safely ignored  because only the <B> component is authoritative:
>    although the preferred representation of the <B> component is in lowercase
>    to minimize its visual impact on human readers, the lower case form can
>    easily be recovered from a mixed case form making the <B> component, in
>    effect, insensitive to case.

True ... but you're avoiding looking at the fact that you've *defined*
these URNs to use lower-case MD5.  If that field contains upper-case
letters, the whole URN is invalid.  Of course, if you see what *looks*
like a gbs URN with upper-case letters there, you might convert them to
lower-case to see if you get a valid URN, but that's like a computer
program with typos in it, a human might be able to get useful
information out of it, but you wouldn't want to depend on a computer
doing so.

OTOH, you could *define* that the MD5 portion is case-insensitive.  It's
your choice.

Dale