Re: [xml-dev] reasons why an XML instance must be validated witha XML sc

[Rick Jelliffe <rjelliffe@allette.com.au>]

Manos Batsis wrote:
> ilango wrote:
>> If so, why should we use XML schema to validate XML?
>>
>> So this is the question I am trying to answer for myself and for my 
>> team here.
>
> Perhaps it's my English, but contrary to the list this sounds to me 
> like "why should should I use XSD to validate my XML instead of 
> something else?" question.
>
> If that is the case, the answer can range from "no reason whatsoever" 
> or "because the plumbing is already there" to "because I like it". You 
> don't provide much info so I can't really tell. Are your 
> tools/frameworks/team dependent/aware of XSD or are you free to choose 
> an alternative? How would that fit in there?

That is much easier to answer. The more that the documents have to be 
tightly coupled with a (relational) DBMS, the more that XML Schemas will 
be the easiest technology; the more that the rest of your documents are 
*not* tightly coupled to a DBMS (or fixed-schema object system), the 
*less* that XSML Schemas will be the easiest technology.

This is because XSD was designed to bring to foreground issues such as 
data representation (shorts, ints, etc) which are quite extraneous in 
the absence a DMBS, plus the availability of tools. (Complex type 
restriction is another one of these issues, where
it  doesn't provide much utility outside certain kinds of non-dynamic 
environments.)

And, as I mentioned before, the more that business rules-ish constraints 
are important, the more that Schematron is useful (whether or not you 
use XSD or RELAX NG or whatever for the base). 

Cheers
Rick Jelliffe