Streaming XML (Was RE: XML Information Set Requirements, W3C Note 18-February-1999)

[Steven R. Newcomb]

[Len Bullard: ]

> > If there is a significant breakthrough, it has
> > been the introduction of two API/interface
> > standards, one formal, DOM, and one grassroots,
> > SAX, both of which are there to solve different
> > but related problems.  The interface standards
> > for markup are unique.  Some of us would have
> > killed for those about five years ago.

[Jonathan Borden:]

> 	Isn't that a grove? I'm saying this
> because when I look at the interfaces in Jade's
> groveoa, they look alot like the DOM (not that
> James defines what a grove is, but by
> implication I assume that this is at least what
> he thinks :-)

I certainly can't speak for James, but I would
like to clear something up:

ISO/IEC 10744:1997 ("HyTime") and, earlier,
ISO/IEC 10179:1996 ("DSSSL") defined and coined
the term "grove".  A grove is the set of objects
resulting from parsing an information resource in
some specific notation.  EVERY GROVE ALWAYS MUST
CONFORM TO A FORMAL MODEL called a "property set".
The "SGML property set" is one such property set,
and it's the property set that governs the
structure and nature of the objects to which
Jade's groveoa interface provides access.  Think
of a property set as a schema for the objects that
result from parsing (and/or from semantic
processing, but that's another story for another
day).

The DOM is not a grove; it is an API.  Until the
XML information set is stable, the DOM is an API
to something that's not rigorously defined.  The
DOM can be implemented as an interface to XML
groves, but not before there are XML groves.  And
there can't be XML groves until there's a property
set for XML.  (Well, no, that's not quite right,
because we routinely make SGML groves from XML
documents.  But that's just a temporary kludge
that only works because of XML's SGML parentage.
Moreover, the SGML Property Set provides for more
complexity than XML groves will ever need to have,
and simplicity is one of XML's most important
virtues.)

There is every reason to believe that the XML
Information Set, once Recommended, will be
expressible as a property set.  Once this is done,
XML objects will be processable, addressable, and
re-usable via the same software that supports the
processing, addressing, and re-use of components
of resources expressed in other notations, with
each such notation described by its own property
set.  In that scenario, all information components
conform to the same object model, the ISO "grove"
object model, so we are able to address (link,
re-use) any kind of thing.

-Steve

--
Steven R. Newcomb, President, TechnoTeacher, Inc.
srn at techno.com  http://www.techno.com  ftp.techno.com

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