Re: "Binary XML" proposals

["W. E. Perry" <wperry@fiduciary.com>]

"Stephen D. Williams" wrote:

> IMHO, SAX events are the wrong model for a more useful binary structured XML.  DOM,
> or rather DOM + optional DOM Deltas, are my current front running model.  For
> protocol use, including passing around any kind of XML for application
> interpretation, XML transmission will generally be done atomically where access to a
> DOM style tree is typical.  SAX, in these situations, seems to be used mainly to
> support a custom parse tree, including just loading values into a 3GL structure,
> rather than for it's other advantage: processing documents too large to load
> completely into memory.

Your model is a more perfect realization of the 'binary' (which I call 'canonical')
philosophy advocated in this thread, and my philosophical objections to it are therefore
even stronger. There is much XML, and many, many uses of it in myriad contexts, which
under particular processing does not exhibit the object model envisioned by its author,
and most especially not a *document* object model. The salient *document*
characteristics of the DOM are document order and the hierarchical parent-child
containment relationship. While a stream of SAX events will be emitted in document
order, the processing of those events may legitimately handle them in a manner which
upsets that order, and its expected implications, as well as instantiating relationships
quite different from parent-child containment and an overall structure which is not the
hierarchical tree you expect. In positing the DOM (or any *document* object model) you
constrain the syntactical possibilities to a narrow range of instantiated object
outcomes which might not fit the needs or expectations of a particular process that
might otherwise have done something useful with an XML document. By further expecting
*particular* DOM nodes to be instantiated, off of which you derive deltas, you
effectively require a comprehensive agreement a priori between the creator and user of
an XML document, covering all of the possibilities of its use. There are, of course,
certain very narrow applications of XML messages for which such tightly constrained
behavior suffices. I suggest that there is much more of use to most of us in the
enormous range of possibilities outside those narrow constraints.

Respectfully,

Walter Perry