[XML-SIG] Value of namespaces (was RE: [XML-SIG] IPC7 results)

Walter Underwood wunder@infoseek.com
Tue, 17 Nov 1998 09:01:05 -0800

>From: Wes Rishel <wes@rishel.com>
>> Patient data
>> Person data
>> name
>> religion
>> date of birth
>> id number
>> Physician data
>> Person data
>> name
>> id number
>> pager number
>>This has presented a problem because using XML we can have only a single
>>content model for Person data. Name spaces would have presented a clear and
>>elegant solution.
>>Surely we are not alone in this matter?

You are not. This may be similar to the model in SNMP MIBs. Those
are somewhat different from the usual object model. Basically, if
a slot is used, it should mean the same thing, but you don't have
to use all the slots. Sort of a cross between a data dictionary
and an object model. And really hard to represent in existing
object models!

A different comment -- it sounds like you are trying to get the 
DTD to enforce the model, rather than just making something that
can be parsed. There are lots and lots of constraints that cannot
be expressed in a DTD (age is positive, these references form a
tree), so enforcing the exact sub-elements of each element is 
just one more thing that can't be enforced in the DTD. Even if
it was possible to specify what was legal, you couldn't specify
that all elements must be there.

Since you've got to do post-parsing checking anyway, trying to 
express too much stuff in the DTD is probably wasted effort.

Walter R. Underwood
wunder@best.com (home)