I am trying to write a schema for an element with two attributes.

<Data compression="gzip" encoding="base64">some xml </Data>

I have to make sure in the schema that value of data (represented by "some xml") should be atleast 1 character in length. How can I define this in schema. Please help. I tried using the code given below, but it doesnt work.

<xs:element name="Data">
    <xs:complexType mixed="true">
       <xs:simpleContent>
            <xs:restriction/>
             <xs:restriction base="xs:string">
            <xs:minLength value="1" />
            </xs:restriction>
         <xs:attribute name="compression" use="required" type="compressiontype"/>
         <xs:attribute name="encoding" use="required" type="encodingtype"/>
      </xs:simpleContent>
    </xs:complexType>
</xs:element>



These are the errors I get:

The BASE attribute must be specified for the RESTRICTION or EXTENSION element
Attribute 'encoding' is not declared for element 'Data'
Attribute 'compression' is not declared for element 'Data'

Any help on this will be greatly appreciated.

First define a simple type that is a restriction of xs:string with a minLength. Then define a complex type with simple content that extends this with attributes:

<xs:element name="shoesize">
  <xs:complexType>
    <xs:simpleContent>
      <xs:extension base="my:minLengthOneType">
        <xs:attribute name="country" type="xs:string" />
      </xs:extension>
    </xs:simpleContent>
  </xs:complexType>
</xs:element>

You don't want mixed="true".

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference