RE: [ubl-ndrsc] [Fwd: FW: [oagis-users] UserArea Extensions for Version 8.0]

["GLACE, Jessica" <JGLACE@lmi.org>]

Title: RE: [ubl-ndrsc] [Fwd: FW: [oagis-users] UserArea Extensions for Version 8.0]

In the Schema Design rules we provided to a client recently we said the following regarding wildcards:

Advantages:Wildcards can be useful when a project is beginning and it is unclear what content will be required at certain points within an XML instance document, or where part of an XML instance document should be unconstrained (e.g., it is a memo or notes field).

Disadvantages:Wildcard declarations place very minor restrictions on the information that can be used in place of them. This can lead to a proliferation of uncontrolled XML instance documents.Wildcard declarations can lead to non-deterministic content models.Use of wildcards may add an additional level of complexity to a schema.

Rule: Data-centric schemas MUST NOT use wildcards.

Justification: Although wildcards can be useful in some situations, the additional level of complexity they add to a schema does not outweigh their potential advantages. In addition, their use can be counter to efforts to control the types of information that can appear in XML instance documents.

Our UBL requirements may be different, but I thought this may be helpful.

Kind regards,
Jessica Glace, CPIM
LMI   (www.lmi.org)
2000 Corporate Ridge
McLean, VA 22102-7805
phone (703) 917-7089
fax (703) 917-7481
jglace@lmi.org
 

-----Original Message-----
From: Eve L. Maler [mailto:eve.maler@sun.com]
Sent: Wednesday, May 29, 2002 4:53 PM
To: Burcham, Bill
Cc: ubl-ndrsc@lists.oasis-open.org
Subject: Re: [ubl-ndrsc] [Fwd: FW: [oagis-users] UserArea Extensions for
Version 8.0]

I would be concerned about putting wildcards everywhere.  It would mean
that the vanilla UBL library would allow all kinds of junk, and XSD
validation would mean little.  But there may be locations where we want
to use it strategically.  (Eventually we'll need a rule about wildcard
usage anyway...)

        Eve

Burcham, Bill wrote:
> When I look at that BOD extension example (below) I see an "open
> content" model (as described by Roger Costello in this ancient
> correspondence
> <http://lists.w3.org/Archives/Public/www-xml-schema-comments/2000JanMar/0159.html>and
> in part three of his eggcelent XML Schema Tutorial
> <http://www.xfront.com/xml-schema.html>).  I think UBL should define an
> open content model, i.e. just about everywhere in a valid UBL document
> instance, it should be easy to hang elements from non-UBL namespaces.  
> What do you think?
>
> -Bill

--
Eve Maler                                    +1 781 442 3190
Sun Microsystems XML Technology Center   eve.maler @ sun.com

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