norman.walsh.name: Comments on /2004/01/29/trainwreck http://norman.walsh.name/2004/01/29/trainwreck/comments.atom 2004-09-09T21:48:37Z Comment 0001 on /2004/01/29/trainwreck http://norman.walsh.name/2004/01/29/trainwreck#comment0001 2004-01-29T19:15:03Z 2004-01-29T19:15:03Z Bill Humphries 233c860663e9e1492fb4db6dc7556550ff410232 http://www.whump.com/moreLikeThis/

Yet another reason to avoid XSD like the plague. XML development shouldn't require one to buy a thousand-dollar IDE to understand what you're doing.

 Comment 0002 on /2004/01/29/trainwreck http://norman.walsh.name/2004/01/29/trainwreck#comment0002 2004-01-29T23:10:15Z 2004-01-29T23:10:15Z Bob DuCharme 98938dda7e59fe014d40dc310f7f83d83aa8c8ef http://www.snee.com/bob

"Avoid like the plague" is a bit much. I consider it a reason to discourage the use of XSD outside of the domains it was optimized for: XMLization of transaction-oriented data and/or data from relational databases. (This is a bit of a simplification, but only a bit.) I don't have much problem with

<xs:element name="quantity" type="xs:integer"/>

but when dealing with data more oriented toward publishable content, then, as Norm shows, XSD gets messier and messier.

I've been thinking for a while that a distinction between publishable content and transaction-oriented data is more useful than the traditional distinction in the XML world between "documents" and "data", since all well-formed XML is both.

 Comment 0003 on /2004/01/29/trainwreck http://norman.walsh.name/2004/01/29/trainwreck#comment0003 2004-01-30T03:20:58Z 2004-01-30T03:20:58Z Norman Walsh 9f5c771a25733700b2f96af4f8e6f35c9b0ad327 http://norman.walsh.name/

I think it's definitely a question of choosing the right tool for the job, and that means known the strengths and limitations of your tools.

But your example strikes me as a little off-topic, Bob. It was never my intent to suggest it was bad to declare types. The tricky bit occurs when someone says:

<quantity xsi:type="byte">34</quantity>

in a document. And even then, it's probably harmless because byte is a restriction of integer. In fact, for simple types it may not matter very much (though I haven't thought through all the possibilities).

 Comment 0004 on /2004/01/29/trainwreck http://norman.walsh.name/2004/01/29/trainwreck#comment0004 2004-06-18T14:35:34Z 2004-06-18T14:35:34Z Jim Brosnan 9a3026d522d5884879a5dc4d7f94a688c451e29f

As a newbie I developed a lot of applications using xml as a command language. I am particulary fond of things like:

<cmd type="delete" item-id="2342"/> <cmd type="insert"/> <cmd type="edit" item-id="2342"/>

Is this a difficult structure to document using xsd?

I can not figure it out, but this article seemed to be close to the topic of elements with the same name but with a differrentating "type" attribute....

 Comment 0005 on /2004/01/29/trainwreck http://norman.walsh.name/2004/01/29/trainwreck#comment0005 2004-06-18T14:50:29Z 2004-06-18T14:50:29Z Norman Walsh 9f5c771a25733700b2f96af4f8e6f35c9b0ad327 http://norman.walsh.name/

It's difficult as in impossible to have an XSD with different content models for the different 'cmd' elements based on the value of the type attribute.

DTDs can't do it either, but RELAX NG can.