Namespaces and DTDs

Didier PH Martin martind at
Thu Mar 11 19:57:40 GMT 1999

HI Bill,


Lisp and XML have a few things in common, like being easy to
determine if they are well formed. Frankly, I think XML will be
better in the long run because it can be validated against various

I am not sure of that.

a) a Lisp document could be made SGML compliant because SGML can let you
define begin and end tag's delimiters (Ex: dsssl).
b) if the previous proposition is true, then you can also change the
delimiters and keep the structural coherency.
c) You could also enforce that a begin and end tag conform to the well
formed constraint.
d) a XML document is a hierarchy and a hisrarchy could be mapped with list
constructs. In fact, as soon as you map lisp to SGML and then to XML, you
notice immediately the similarities. There is formal transformation possible
from one structure to the other. In mathematical term would coud talk of
"topological" transformation from one to the other. Their structure are
similar enough to transform one into the other.

Conclusion: we should not take what Jonathan said so lightly and do some
homework fisrt.

This said, I agree that XML could potentially be more succesful than lisp or
SGML or (fill here less than popular good ideas) but this is for other
reasons than technical reasons. For instance, this could be very popular
because the web is popular and XML benefit form the aura effect. Also
because, important software manufacturer are behind it and put compliant
products on the market. Also because poeple don't want to miss the next Web
big success, etc... This has nothing to do with technical vertues but more
with marketing vertues. But surely not because XML is bettern than lisp
because it could be validated against different schemas.

a) XML has the advantage, because of its strict syntax (compared to SGML
omitags) that a receiver do not need to validate the structure to interpret
the XML document. In fact, there is a high probability that interpreters
would "hard code" in some ways what to do for each element and this without
the need of a DTD. (except for style language that will "hard code" tree
manipulation and formatting object model)
b) If a DTD is necessary why not use SGML except for a marketing advantage
c) An otehr usage of XML is to separate the content from the rendition. In
this case, most of browsers' style engine won't contain a validating parser
and therefore validation mechanism is irrelevant.

Conclusion: XML will be better simply because it has marketing momentum not
because of its technical merits period. The whole difference between SGML
and XML is that the receiver do not necessarily need validation to interpret
the document (because of the "well formed" constraint). But from the
marketing point of view it has huge advantage. New domain languages could be
created and big software manufacturers could again regain some control by
creating a domain language and let the numbers create a de facto standard.
In fact, HTML by being a standard domain language is more a threat to big
manufacturer than XML is. So, if XML is to be more popular this is surely
for marketing reasons :-)

Didier PH Martin
mailto:martind at

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