RE: [xml-dev] Here's why it's not always a good idea to embed validation

["Michael Kay" <mike@saxonica.com>]

> 
> Your presentation looks good, but I'm not sure it goes far 
> enough. Was there ever a good reason to embed validation 
> information in an instance document? Isn't that fundamentally 
> backwards, like trusting a thief because /he says/ he's not a thief?
> 

The only possible use case I can see for putting validation information in a
document is if process A wants to create a message saying "Please validate
this document against schema X", and then pass that message to process B to
do the validation. Here it is A that cares about the validity of the
document, not B.

But it's not a good use case, and certainly not good enough to justify the
feature. This was an SGML feature that should never have made it into XML
DTDs, and certainly not into XML Schemas.

Michael Kay
http://www.saxonica.com/