xml-dev - RE: Parser Behaviour (serious)

[Peter Murray-Rust <peter@ursus.demon.co.uk>]

[Note: "serious" in my title was originally meant to make sure it wasn't an
April fool a la ZML, but it is clear that this really *is* a serious issue.]

At 02:42 PM 4/2/00 -0400, Didier PH Martin wrote:
>
>As Steve pointed that out, if the standalone="yes" attribute/value is
>included in the xml declaration, then what the parser does if external
>entities are present in the XML document and that these external entities
>are declared in the DTD? Are these external entities unresolved?

My understanding is that non-validating parsers have no obligation to
resolve external entities if they don't want to. They don't even have to be
consistent - they could decide there was a memory limit on a particular
document and just go on strike.

I have posted the example before, but a good example of the problem is the
use of external entities in SVG with the Adobe plugin. [The plugin is
excellent - it's just that whatever machinery it uses doesn't expand
external entities. Presumably even though it may be used with a DTD, this
doesn't trigger the activity]. If you include your picture as entities it
doesn't get displayed! Fairly graphic illustration of my point - I showed
it at Xtech2000.

So my summary is:
	- The experts (on this list) cannot agree precisely what a parser should
and should'nt do with various combinations. these include:
		- the intention of the parser (non-validating, or validating in
non-validating mode?)
		- the use of standalone
		- the motivation of including a SYSID for the DTD
		- the use of external entities
	- There is no way that this community can say it has consistent
interoperation at this level.
	- We have a serious problem.

My invitation is for someone or some group to describe exhaustively what
the problem(s) actually are. It might be that we can then all agree on
appropriate behaviour under every combination. In that case the document
would consist of a definition of conformance. Presumably a given parser
could have a label stating its conformance to this document. And when
XML-based software was produced which included a parser (and most will :-)
then the behaviour of the parser should be stated. Ideally it should be
switchable, but if not it would presumably be possible to transform an XML
document using another parser to give an input which was conformant.
Horrible, but it stops people manually editing files.

So:
	The general response shows there is a problem and it must be tackled.
	I assume there is no W3C or OASIS activity which is tackling this
	We need (a) volunteer(s). It will be a lot of hard work, but it will make
them feel really good and catapult them to stardom.

	P.


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