Re: PLink availability/feature requests

From: Eric Armstrong (
Date: Wed Apr 25 2001 - 14:49:04 PDT

Murray Altheim wrote:
> I'm not sure how to understand the approach you've taken regarding
> node identifiers. By definition, at least in SGML and XML, IDs are
> always unique within a document...
> ...
> Sorry if this is a bit of a brain dump, and that my response is
> so Web-centric. Like many of us who have watched the evolution of
> the Web, I've become somewhat cynical about the integrity of the
> system, and my feeling is that it's better to design into a
> document management system its known (and likely unfixable) flaws.
Thorough brain dumps are, in fact, highly appreciated!

The problem with SGML and XML, however, is the very concept of a
"document". As an *interchange* mechanism, that concept is very
useful. I transmit a document to you, you receive it and comment
on it.

But as a *storage* mechanism, that concept has led to the lack
of granular addressiblity and modular reuse that typifies our

The notion that an ID is unqiue only within a document, in
particular, totally prohibts the use of that ID in any other

But the notion of dynamic linking among nodes to construct new
documents by transcluding pieces of other documents depends on
IDs that are *not* document-centric, but which are instead

And given that nodes want to exist in multiple distributed
repositories, and be shared when and as needed, implies that
the IDs must be globally unique.

The notion of an ID is priceless. But the SGML/XML definition
thereof is useful only in a document-centered universe. The
lack of global uniqueness (unfortunately) makes them pretty
nearly useless even for interchange in a granular, dynamically
linked world.)

This archive was generated by hypermail 2.0.0 : Tue Aug 21 2001 - 17:58:05 PDT