Re: [xml-dev] xsd:anyType and xsd:any

[noah_mendelsohn@us.ibm.com]

Shlomo Yona asks:

> I was not able to fully understand the difference between an xsd:any
> and an element with a type xsd:anyType.

Very different.  xsd:anyType is a type, like xsd:integer (though 
xsd:anyType is special in that it can act as a simple or complex type, and 
it places essentially no restrictions on the tree that it validates -- 
thing of it loosely as the Schema language's analog of java.lang.Object). 
A sample use would be:

        <xsd:element name="e" type="xsd:anyType"/>

This would mean that elements named <e> can have any content, any 
attributes, etc.

xs:any is a wildcard, usable as a term in a content model.  For example:

        <xsd:complexType name="T">
        <xsd:sequence>
                <xsd:element ref="A"/>
            <xsd:any />
                <xsd:element ref="C"/>
        </xsd:sequence>
        </xsd:complexType>
 
Elements of type T must have content <A/><???/><C/>, where <???> can be 
any named element.  Now, if you look really closely there is an 
approximation to the definition of xsd:anytType given for reference in the 
Recommendation, and it uses an xsd:any wildcard as the means of saying 
that it allows any elements. 

I hope you'll see that most of your questions are answered once you get 
the above straight.  I would encourage you to carefully read the schema 
primer [1], or some of the good books on W3C XML Schema (Priscilla 
Walmsley's is among the one's that's very well respected. [2]).

Noah

[1] http://www.w3.org/TR/xmlschema-0/
[2] 
http://www.amazon.com/Definitive-XML-Schema-Priscilla-Walmsley/dp/0130655678/ref=sr_1_1/103-2086530-8739813?ie=UTF8&s=books&qid=1174404823&sr=8-1

--------------------------------------
Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
1-617-693-4036
--------------------------------------








"Shlomo Yona" <S.Yona@F5.com>
03/20/2007 11:08 AM
 
        To:     <xml-dev@lists.xml.org>
        cc:     (bcc: Noah Mendelsohn/Cambridge/IBM)
        Subject:        [xml-dev] xsd:anyType and xsd:any


Hello,
 
I was not able to fully understand the difference between an xsd:any and 
an element with a type xsd:anyType.
 
Is there any difference?
Do both wildcard methods refer to any child element(s) or does one or both 
refer to a wildcard subtree?
What should be the parse mode (parserContents) for processing xsd:anyType? 
Should is be same as xsd:any’s “skip” or “lax” or “strict” or perhaps to 
something else?
The section 3.4.7 Built-in Complex Type Definition (in 
http://www.w3.org/TR/xmlschema-1/) says, if I understand correctly, that 
the subtree should be processed in “lax”. Is that so?
What’s the difference, if any between the following wildcard definitions 
(with regards to the depth of subtree they refer to, the processing mode 
and any other issue):
·         xsd:any
·         element definition with type=”xsd:anyType”
·         a complexContent that has a restriction base=”xsd:anyType” with 
an xsd:anyAttribute namespace=”##other” and processorContents=”lax”
·         a complexContent that has a restriction base=”xsd:anyType” with 
an xsd:anyAttribute namespace=”##other” and processorContents=”skip”
Thanks.
 
Shlomo.