[XML-SIG] parsers and XML

tpassin@home.com tpassin@home.com
Thu, 10 Aug 2000 19:45:57 -0400

Michael McLay told us about his PCB layout XML schema -

[much interesting description elided]

> I'd appreciate feedback on the approach used to define pointers
> between structures.  Is there a standard way that would also be
> efficient for a file that may contain millions of these references?
> I would be interested in seeing the example rewritten using any
> alternative notations, such as XPATH.
Michael, this is very interesting.  Looking at your examples, I didn't think
the nesting levels were especially deep.  As for the references, you
certainly want to use IDs in elements, as you are.  But what about the colon
in the reference IDs?  That's not according to the Namespace Rec, is it?
Maybe another character would be better.

If you are interested in alternative access methods, I'd suggest getting the
following book if you don't already have it:

Data on the Web
Abiteboul, Buneman, and Suciu
Morgan Kaufmann Publishers
ISBN 1-55860-622-X

This book discusses semi-structured data (and XML data), and storing and
accessing it.  It also covers dealing with cycles in the data graphs.

I think the actual reference ID values would depend on how they structure
would be stored.  If they are going to be expanded into existing data
structures, the numbers would probably have to be translated into some
internal form expected by the existing system, so it hardly matters what
their exact format is (except for human reviewability, of course).  With
millions of elements possible,maybe a high-powered object database would be
a good thing to look at.  In that case, you'd want to see what kind of
object IDs the ODBMS wants to use.

Since the PCB can be seen as a sort of drawing, I was thinking that using
SVG as a base might be interesting.  But if you are trying to map to the
existing systems as closely as possible, that would be different.


Tom Passin