Re: [core] Review of CoRAL

Christian Amsüss <christian@amsuess.com> Thu, 08 November 2018 14:45 UTC

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Date: Thu, 8 Nov 2018 15:45:48 +0100
From: Christian =?iso-8859-1?Q?Ams=FCss?= <christian@amsuess.com>
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Subject: Re: [core] Review of CoRAL
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Hi Klaus,

some more points came up pushing forward my implementation:

* On "Why are there bare-words as relation strings": During
  refactoring[1], I found why I had that -- the append-rel path type
  seemed to indicate that the rel should be something usable here.

  Now the code in the draft is a bit vague here (`format(relation,
  "x")`), and there's no text on it yet. Any ideas yet on how I'd come
  from a URI to an appendable string (like uri_to_rel(x) = rightmost
  substring of x where x in [a-zA-Z.0-9-])? Will it be sufficent on a
  constrained device that has hardcoded knowledge of what the URIs mean
  to only store uri_to_rel(rel_number_to_uri(n)) for all n in the
  supported profiles?

* current base IRI: Current base IRI keeps being updated to
  current context IRIs. That is a good idea in terms of compact
  representations, but means that local references can not be expressed
  "deep in there".

  Say I want to say that "</temp> is described by
  <http://example.com/TemperatureSensor>, where
  <http://example.com/TemperatureSensor> has author <mailto:..>, change
  log at <...> *and is also available at </descr>*" (like a local cached
  version).  By the time I talk about the thing at example.com, my
  context and current base URI is http://example.com/..., and I can't
  say </descr> any more meaning a local resource.

  (Note that this is a bit of a similar situation as with RFC6690, but
  sans all the confusion.)

  In this very example, one could work around by saying that "is also
  available at" is symmetric, so one could instead say "Furthermore,
  </descr> is also available at <http://example.com/TemperatureSensor>",
  which would be another toplevel link, but it means that a *generic*
  link-format document can not necessarily be expressed easily.

  I have no concrete proposal of how this could be done better. One idea
  is to allow expressing "rev" and not only "rel", but have not thought
  through whether this solves the issue completely at all.

Best regards, and sorry for the somewhat chaotic way in which my
observations and questions arrive
Christian


[1] which has led to micrurus to be what I believe to be correct again,
not only w/rt flat CIRIs, but also with base URI changes and
delta-compressed relation numbers

-- 
To use raw power is to make yourself infinitely vulnerable to greater powers.
  -- Bene Gesserit axiom