Cart
|
[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Call for unifying and clarifying XML 1.0, DOM, XPATH, and XML Infos
[Henry Thompson:]
> [The XML Schemas draft] certainly
> addresses the question of how a document containing multiple
> namespace-qualified information items can arrange for them to be
> validated by independent, pre-existing schemas for those namespaces.
Exactly how does such validation happen? For example:
Namespace A's independent schema provides that B elements must contain
a C element and may contain a D element, and that no B may appear
inside a C or a D, and no C or D can appear outside a B. In other
words (if you'll forgive me for expressing this using traditional DTD
syntax):
<!ELEMENT A:B ( A:C, A:D?)>
<!ELEMENT A:C ( #PCDATA)>
<!ELEMENT A:D ( #PCDATA)>
Namespace F's independent schema provides that G elements may contain
H elements and/or PCDATA, that no G may appear inside an H, and that
no H may appear outside a G.
<!ELEMENT F:G ( F:H | #PCDATA)* >
<!ELEMENT F:H ( #PCDATA) >
Now I want to write documents in which, within the constraints
outlined above, I can freely mix A:B, A:C, A:D, F:G, and F:H elements.
In order to make it possible to interchange such documents
meaningfully (in a vendor-neutral, application-neutral etc. context),
I need a way to tell whether my use of each of these namespaces
conforms to its governing constraints. Following are some questions
that, for whatever reasons, I haven't been able to answer
satisfactorily:
(1) What do I have to do to validate my document against namespace A's
constraints independently of any validation of namespace F's
constraints, and vice versa?
(2) If an A:B contains an F:G, I gather that it's OK from the
perspective of namespace A (right?). What does
namespace-A-specific software do with the F:G? Does it see the
F:G at all? If the F:G is hidden, how did it get hidden? Should
the A-namespace-specific software look inside the F:G for A:C
and/or A:D elements? Is it OK (and/or necessary, from the
perspective of namespace A's constraints) for A:C and A:D elements
to be inside the F:G element, or not?
(3) From the perspective of namespace A, what happens to the data
content of an F:G element that's inside an A:B? Similarly, what
happens to the data content of an F:H element that's inside a F:G
element that's inside an A:C?
(4) Why isn't it possible for an element to be both an A:B and an F:G?
There seems to be no reason to prohibit this, because it does not
violate the constraints of either namespace A or F. There seems
to be a good reason to allow it; otherwise, one must insert markup
for an element that serves no purpose other than to accommodate a
weakness in the XML namespace paradigm. And, there's no basis for
deciding, when authoring such a document, whether the A:B should
be inside the F:G, or vice versa.
-Steve
--
Steven R. Newcomb, President, TechnoTeacher, Inc.
srn@t... http://www.techno.com ftp.techno.com
voice: +1 972 517 7954
fax +1 972 517 4571
Suite 211
7101 Chase Oaks Boulevard
Plano, Texas 75025 USA
xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i...
Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ or CD-ROM/ISBN 981-02-3594-1
Please note: New list subscriptions and unsubscriptions
are now ***CLOSED*** in preparation for list transfer to OASIS.
|
PURCHASE STYLUS STUDIO ONLINE TODAY!Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced! 
Download The World's Best XML IDE!Accelerate XML development with our award-winning XML IDE - Download a free trial today! Subscribe in XML format
|
|||||||||
