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- From: David Megginson <email@example.com>
- To: xml-dev <firstname.lastname@example.org>
- Date: Sun, 29 Aug 1999 14:51:37 -0400 (EDT)
Paul Prescod writes:
> How can you know, in 1999, whether Internet Explorer 5.0 will work with
> HTML 6 documents? You cannot. If robust behavior is your primary goal
> then you must presume not.
I agree that there needs to be some sort of versioning available -- it
could be an html:version attribute (the best solution, I think), or
perhaps just the version of the DTD used in the DOCTYPE declaration
I think that Namespaces are the wrong tool to use for versioning,
because using them that way makes easy, typical jobs much harder, and
that's just bad design.
> > If you don't believe that versioning is a problem on
> > the Web, then look at the lack of even Java 1.1 applets for general
> > use (because Netscape 3.0 doesn't have a Java 1.1 VM).
> What would you have JavaSoft do? Pretend that Java 1.1 programs are
> really Java 1.0 programs so that the crash occurs deep in the JVM
> instead of at the point that the problem is first detected? "Hmmm. It's
> looking for a method I don't have. I'll just return NULL and hope it
Fortunately, XML isn't source code (or compiled code), so we don't
have the same problem -- I was using that example only to demonstrate
that once there's software deployed that recognizes a certain set of
XHTML Namespaces (preferably a set with one member), it will be very
difficult to introduce any new Namespaces.
> No version 1.x software can magically handle version 2.x data without a
> well-defined graceful degradation mechanism. You are asking the XHTML
> people to pretend that they have that mechanism when they do not.
They already have the mechanism: if you see an unknown attribute,
ignore it; if you see an unknown element, ignore its start and end
tags and process the content. It's not elegant, but it's workable.
That said, as I mentioned above, I agree that some sort of versioning
is needed -- the three-Namespace approach just seems equivalent to
amputating my leg to get rid of a wart.
All the best,
David Megginson email@example.com
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