Streams, protocols, documents and fragments

[Marcelo Cantos]

On Fri, Feb 26, 1999 at 08:04:40AM -0800, Tom Harding wrote:
> David Megginson wrote:
> 
> > -- a general-purpose DOM would be *extremely* inefficient for
> > handling things like vector graphics or 3D worlds (to name only
> > two), though it is always possible to expose their optimised
> > object models through a DOM interface later if necessary.
> 
> In lots of applications, the data can't stay in an XML
> representation for very long anyway, because of what you're
> integrating it with/displaying it on/routing it through/converting
> it to/storing it in/etc... I view the DOM as a standard, OO way of
> manipulating the contents of a document.  It lets applications get
> work done, even without taking an end-to-end OO approach.  Perhaps
> I'm showing my bias here ;D

It's the translation process that hits hardest, however.  C and
FORTRAN compilers rarely build parse trees, because it is much more
efficient to generate code directly from token streams.  What you seem
to be suggesting is that a parser should pump an event stream straight
into DOM and then into another domain-specific structure.  This is
just adding an often gratuitous layer that can incur a massive
performance penalty for large documents (a 3D model of a refinery,
say).

In such circumstances I would much rather build the domain-specific
structure straight from the event stream.  (In fact, I have serious
reservations about using XML at all for 3D model transmission and
storage -- the markup tends to grossly outweigh the content, which
consists primarily of numbers.  Compression during transport _and_
storage would be a must).


Cheers,
Marcelo

-- 
http://www.simdb.com/~marcelo/

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