XML Schema Part 7: What Schemas Can't do

As described in the January 2005 issue of CPU - Computer Power User magazine.

Examples

A) Downloadable ZIP File

• There are several examples here -- why not download the whole lot as a ZIP file -- jan05.zip -- and install them on your own machine?

B) The example XML documents

To play with these documents, simply load them into an XML or XML schema editor and test them for validity, or load them into a browser and view the results. Some editors will test for validity automatically as the file is loaded, while others will require that you select to validate.

• Non-deterministic DTD Example: An example XML document including a non-deterministic DTD -- DTD-non-deterministic-example.xml (plain text version at: DTD-non-deterministic-example.txt). This document should be rejected by an XML processor, since the DTD is non-deterministic. This is the behavior seen in the Oxygen XML Editor (http://www.oxygenxml.com). However other editors, such as XML Spy (http://www.xmlspy.com) happily accepts this DTD, and do not indicate an error.
  
  
• Schema Violoating the Unambiguous Particle Attribution (UPA) Constraint: The schema non-UPA-deterministic.xsd (plain text at: non-UPA-deterministic.txt) Should be rejected by an XML schema processor, as the schema violates the UPA. The document non-upa-example.xml (plain text at: non-upa-example.txt) references this schema. This schema and document should be rejected by an XML processor. This is the behavior seen in the Oxygen XML Editor (http://www.oxygenxml.com). However other editors, such as XML Spy (http://www.xmlspy.com) happily accepts this DTD, and do not indicate an error.
  
  

C) Some XML Editors with Validation Features

See the listing provided in the March 2004 CPU article (http://www.iangraham.org/writing/cpu-articles/mar04/). Note that some of these editors flag violations of the non-deterministic content model contraint (or UPA violation for schemas), while some don't.