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


Help: OASIS Mailing Lists Help | MarkMail Help



   Re: [xml-dev] XPath/XSLT 2.0 concerns

[ Lists Home | Date Index | Thread Index ]

Aaron Skonnard wrote:

> How well the "back end" deals with exceptional conditions is
> implementation dependent. For example, if you write a Web service in
> .NET like this:
> [WebMethod]
> public double Add(double x, double y) {
> 	return x+y;
> }
> It expects an Add element with two child elements, x and y. If, however,
> you send it an Add element with foo and bar child elements, or no child
> elements, or something else off the wall, it will happily return 0. This
> is a false positive, where most developers would expect an exception.
> Performing schema validation before the method is called moves such
> error handling down a layer and protects you from this type of thing
> happening.

There are some controversial design choicesin the above, but the 
argument for schema validation because it pushes some things down a 
layer does have some merit.

But I don't buy it.  If I'm going to be accepting transactions encoded 
in XML my *business* level validation is going to be doing a lot of 
looking up part numbers in catalogues and buyer-IDs in other databases 
and pricing rules and so on and so on.  If I'm already doing this in a 
high-volume transaction processing application I think it's going to be 
hard to justify a full-dress schema validation step when the 
business-validation code already knows the data types and can do the 
data conversion right down there inline, and fail deterministically if 
something isn't as expected. -Tim


News | XML in Industry | Calendar | XML Registry
Marketplace | Resources | MyXML.org | Sponsors | Privacy Statement

Copyright 2001 XML.org. This site is hosted by OASIS