[XML-SIG] DOM: Multiple proxy problem
Fred L. Drake
Fred L. Drake, Jr." <email@example.com
Wed, 7 Oct 1998 10:21:28 -0400 (EDT)
Markus Fleck writes:
> This must be what Tim Berners-Lee meant when he said (at WWW7):
> "You need to build a system that is futureproof; it's no good just
> making a modular system. You need to realize that your system is just
> going to be a module in some bigger system to come, and so you have
> to be part of something else, and it's a bit of a way of life."
> I found this to be a very nice "feature" of XML, but I also think that
> this implies that strict, formal DTDs shouldn't generally have the
> importance that they have now. Requiring a DTD for each XML document
Actually, I don't see how DTDs "solve" the "futureproofing" problem,
and I'm not sure that "futureproofing" is well defined. (If it is,
I'd be very disappointed!) There's a lot we can predict about the
future, and a lot we can be wrong about.
Given XML+Namespaces, it probably isn't important that any given
document has exactly one document type, and the form taken by document
type definitions will most likely change. However, I don't think the
need for some formal notion of document types will change anytime soon
(am I setting myself up for a big fall? ;). The need for specifying
"intended interpretation" for document types will remain. DTDs
(including the non-formal part) are one way of doing this, and offer
particular benefits and limitations. They're also the best shared
means of doing this at the time -- DCD and XSchema just aren't quite
> may solve the problem of "futureproof" file formats, mostly because
> it can serve as some kind of documentation, but it still doesn't enable
> a legacy XML application (using an older version of a DTD) to
> non-destructively process data that has been created using a
> more recent, but upwards-compatible version of that DTD.
Another concern is with well-formed XML that doesn't conform to a
DTD. It is entirely reasonable to handle instances which contain
completely ad-hoc tagging or elements affiliated with alternate
namespaces. An application need not be "legacy" to have problems with
input data when attempting to perform minimal transforms!
> But then, maybe the future isn't really important.
Maybe not. But I'll let my kids decide that after I die. ;-)
Fred L. Drake, Jr. <firstname.lastname@example.org>
Corporation for National Research Initiatives
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