Versioning DTDs?

[Mark Birbeck]

I think Stephen Mohr referred to this recently on the list. Anyway, even
if he didn't, one possible solution to this is discussed in his book
"Designing Distributed Applications". He addresses the need to send data
to different versions of client software - which is more sophisticated
than just have different versions of DTDs.

Regards,

Mark Birbeck
x-port.net Ltd.

> -----Original Message-----
> From: Marcus Carr [mailto:mrc at allette.com.au]
> Sent: Monday, October 25, 1999 12:09 AM
> To: xml-dev at ic.ac.uk
> Subject: Re: Versioning DTDs?
> 
> 
> 
> Ken Gentle wrote:
> 
> > In developing an e-commerce dialog (using XML, of course), 
> we've determined
> > that the messages need to be versioned.  Specifically, 
> we'll need to have
> > some way of versioning a DTD such that the XML parser can 
> "figure out"
> > which version of the DTD to use.
> >
> > As the XCatalog stuff (for PUBLIC entities) is not widely 
> supported yet
> > (based on my rather naive perspective), simply mapping the 
> PUBLIC ids to
> > different DTDs won't work.  Additionally, there is the "change-over
> > period":  what if I have messages/documents to process in 
> my "queue" when
> > the publicly available DTD changes?  If the structure of 
> the two versions
> > of the DTD are incompatible, I've introduced a problem...
> 
> I have used OmniMark to manage the dependancies for an SGML 
> dataset by putting APPINFO in the
> declaration, fixed attributes in the DTD and attributes 
> representing the current DTD in the
> document. I was able to ensure that everything matched before 
> anything was processed except
> for the start tag of the DOCTYPE element. Although it was 
> written for an older version of
> OmniMark and contains a superset of what you need, if you 
> want it, send me offlist mail.
> 
> 
> --
> Regards,
> 
> Marcus Carr                      email:  mrc at allette.com.au
> ___________________________________________________________________
> Allette Systems (Australia)      www:    http://www.allette.com.au
> ___________________________________________________________________
> "Everything should be made as simple as possible, but not simpler."
>        - Einstein
> 
> 
> 
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