Re: 4.3 SGML addressing

At 12:33 PM -0800 3/4/97, Tim Bray wrote:
>Background: the draft spec supports SGML-style addressing, traditional
>IDREF(S) and also by entity name.
>4.3.a Should we support this type of locator?
At least. I think TEI xptr syntax should also be in there.

>4.3.b Should we support entity addressing by name?

We should allow the use of entity addressing for LOCSRC or its equivalent,
if we have one (and we probably should). I'm not sure that _linking_ to an
entity itself makes that much sense (if we preserve the SGML notion that
entities are basically abstractions of storage structures).

is there a 1-1 correspondence between WWW "resources" (anything with a URL)
and SGML entities?

>4.3.c Should we support element addressing by ID attribute?

>4.3.d Should we support a combination of these two?

I think that a LOCSRC facility accomplishes that. If we restrict LOCSRCs to
be entities only, and entities to be used only as LOCSRC, I think we cover
all the essential ground, though we do in fact lose some power.

>4.3.e What syntax should we use?

URL syntax for everything... I made one proposal, but others would probably
serve aas well or better. I think that some servers will provide
server-side fetching of sub-components, but that we should provide a
fragment-based mechanism for accessing data withing a parsed sub-tree. As
Gavin has noted, this means that an author's decision to use fragment-style
querying will prevent certain efficiencies in the server/browser
collaboration, but keeping the spec focused on the language and the client
side seems like such an important simplification that we should do it.
Nothing will prevent the use of external entities or specialized server
link resolution, but we will not standardize such mechanisms -- any more
than HTML has had to standardize server-includes, despite their great

   -- David

David Durand              dgd@cs.bu.edu  \  david@dynamicDiagrams.com
Boston University Computer Science        \  Sr. Analyst
http://www.cs.bu.edu/students/grads/dgd/   \  Dynamic Diagrams
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