Re: [urn] gbs Name space identifier

worley@ariadne.com (Dale R. Worley) Thu, 17 October 2019 01:59 UTC

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From: worley@ariadne.com (Dale R. Worley)
To: Philip R Brenan <philiprbrenan@gmail.com>
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Date: Wed, 16 Oct 2019 21:59:32 -0400
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Subject: Re: [urn] gbs Name space identifier
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I see the new version as an enormous improvement.  One aspect that
you've made clear is that for any given <B> value, there can be only one
<G> value (although you cannot compute <G> from <B> unless you happen to
have a copy of the topic to hand).

As has been noted, URNs are *names* while URLs are *locators*, and URNs
do not require a resolution process to locate the named resource.

However, I think there are some aspects of the exposition that should be
improved:

Under "Resolution", it says:

    Equivalence is determined by comparing (ignoring case) the <B> components
    of the two topics to be compared.  If they are equal the two topics are
    considered to be equal. Otherwise they are considered to be unequal even if
    the underlying content is in fact identical. The characteristics of the MD5
    sum ensure that only a small number of topics will be unnecessarily
    duplicated as a result of such false positive equivalences.

I do not see how "the underlying content is in fact identical" without
generating the same <G> and <B>.  I suspect you mean that there can be
two topics that have no *meaningful* difference but nonetheless have
different <B> or <G>.

Under "Security and Privacy", it says:

   The validity of the URN can be checked as follows:

However, these actions can only be done if one possesses not just the
URN but also the content it refers to.  Usually "validity checking"
names a procedure that only requires the URN as input.  So it would help
if you expanded this sentence.  Perhaps, "The validity of the URN for a
topic can be checked as follows:"

Under "Inter-operability", it says:

   The case of the letters chosen is immaterial and can be safely ignored in
   all computations on the proposed URN as only the <B> component is used for
   comparisons.

The case of letters can be ignored for comparing URNs, but when copying
or transmitting URNs, case has to be preserved, because only lower-case
letters are valid in the <B> part of the URN, and the case of the
letters in the <G> part must match that of the text from which it was
derived -- so if you send the URN to another process, you have to get
the case right.  So you want to narrow this statement.  Perhaps, "For
many computations, the case of the letters in the URN is immaterial and
can be safely ignored..."

Dale