RE: DTD's

[Al Snell <alaric@alaric-snell.com>]

On Thu, 17 May 2001, Frank Richards wrote:

> First, at design & code time, it provides a formal schema which acts as a
> contract between all the users and creators of the documents -- if all
> documents created are valid, and all readers can read any valid document,
> then your system will work.

Assuming that the validity test can really test the validity of the
documents... DTDs will just pull out basic syntactic problems,
mainly. Even schemas can't check for everything... it can't check that
your image URLs point to valid PNG images!

However, your code that processes these XML documents should end up
performing all these checks. If your <IMG> doesn't have an SRC attribute,
then you will pick that up; the code can check the semantics... if the XML
coming in is invalid, your code will pick this fact up anyway and throw
appropriate exceptions. Validating it as well will be a waste of time
IMHO. Interoperating systems have never had need for seperate validation
stages before, except checking checksums to screen out modification of the
data in transit!

> 
> Frank
> 

ABS

-- 
                               Alaric B. Snell
 http://www.alaric-snell.com/  http://RFC.net/  http://www.warhead.org.uk/
   Any sufficiently advanced technology can be emulated in software