Problems with Sun xmlInstance Generator

Question

I am completly new to this Sun-tool and when I try to generate a xml instance from a very simple schema
I get this error:
Exception in thread "main" java.lang.InternalError: namespace URI is null
at com.sun.msv.util.StringPair.<init>(StringPair.java:28)
at com.sun.msv.verifier.regexp.CombinedChildContentExpCreator.get(Combin
edChildContentExpCreator.java:210)
at com.sun.msv.verifier.regexp.ExpressionAcceptor.createChildAcceptor(Ex
pressionAcceptor.java:113)
at com.sun.msv.verifier.Verifier.startElement(Verifier.java:175)
at com.sun.msv.generator.DOM2toSAX2.onElement(Unknown Source)
at com.sun.msv.generator.DOM2toSAX2.onElement(Unknown Source)
at com.sun.msv.generator.DOM2toSAX2.traverse(Unknown Source)
at com.sun.msv.generator.Driver.run(Unknown Source)
at com.sun.msv.generator.Driver.main(Unknown Source)
Like the example given in the "howto" I typed following in command line:
java -jar xmlgen.jar Untitled2.xsd -root {}root
Here is my schema-file:
Untitled2.xsd
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified">
     <xs:element name="root">
     <xs:complexType>
     <xs:sequence>
     <xs:element name="myElement" type="xs:string" maxOccurs="unbounded">
          <xs:annotation>
               <xs:documentation>Comment describing your root element</xs:documentation>
          </xs:annotation>
     </xs:element>
     <xs:element name="myElementB" type="xs:string" maxOccurs="1"></xs:element>
     </xs:sequence>
     </xs:complexType>
     </xs:element>
</xs:schema>
Did anyone work with this tool and has some experience with it? Or can give me some examples for using?
Please help!!

Answer 1

I think that the elementFormQualified attribute requires these other attributes also: targetNameSpace="http://myURL" xmlns="http://myURL" This syntax defines the namespace that will be used for the actual xml. Then in the actual xml next to the topmost element, you would have this: xmlns="http://myURL". This is because there can be conflicts among elements with the same name. For example, you might have half a dozen or more types called "name" in some xml. This identifies which definition of name is being used in a particular case. The xmlns syntax identifies a particular default name space for the xml (and xsd) that it appears in. That way, you don't have to use a prefix for each and every element and attribute that is user-defined in the xml (or xsd). For example, if you say, <Mine xmlns="http://myUrl"> then a child tag such as <yours> does not need an element such as <m:yours>. Otherwise, it would. This way, only element and attribute names that come from some other schema need to have a prefix. Confusing at first, but it does work.