OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.

 


Help: OASIS Mailing Lists Help | MarkMail Help

relax-ng message

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [Elist Home]


Subject: Re: [relax-ng] close schema language


David RR Webber - XMLGlobal wrote:

> Message text written by Eric van der Vlist
> 
> Schematron is the only language I know where "everything which is not 
> forbidden is allowed", the main principle of the other languages being 
> rather that "everything which is not allowed is forbidden" which, by 
> itself, is "closed".
> <<<<<,<''
> 
> Eric - excellent points.


Thanks!


> 
> Having worked for many years in Prolog - there's another facet to
> this declarative / assetive world which can be fun - ie - somethings
> that you never even realized can also be allowed - together. 
> 
> It teaches you that you must always explicitly assert the
> "Otherwise - do nothing" facts - which is definately a good habit
> to get into.
> 
> Java - throw / catch users note - weird behavioural treatment of
> fringe error conditions relates!!


Yes. There is a difference, though between a schema language (especially 
when it is used to validate documents) and a development language and I 
think that most of the people see a XML schema as a kind of firewall 
which will protect them from the unexpected -these "otherwise" facts-.

Foreign namespaces (and "open" schemas in general) are then seen as 
potentially dangerous since it's like removing a part of the firewall 
exposing the applications to more unexpected facts and requiring a 
different design.

Among the RSS 1.0 Working Group, for instance, everyone agreed to accept 
foreign namespaces elements, but the majority decided to accept them 
only when the content model (simple/complex) was not changed showing 
that the notion of open/close is relative ;=) ...

Eric
-- 
Rendez-vous  Paris pour le Forum XML.
                    http://www.technoforum.fr/Pages/forumXML01/index.html
------------------------------------------------------------------------
Eric van der Vlist       http://xmlfr.org            http://dyomedea.com
http://xsltunit.org      http://4xt.org           http://examplotron.org
------------------------------------------------------------------------



[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [Elist Home]


Powered by eList eXpress LLC