- From: <noah_mendelsohn@us.ibm.com>
- Date: Wed, 30 Jan 2002 15:17:08 -0500
- To: jacek@systinet.com
- Cc: Martin Gudgin <marting@develop.com>, XML Protocol Discussion <xml-dist-app@w3.org>
Yes, you're right, my mistake, I oversimplified the explanation of the examples. I think we agree on the key point, which is that XML Schema is not an appropriate description language for the directed graphs used by the encodings. It would be easy to construct two examples that were very different from a schema point of view, and identical per the graph model. ------------------------------------------------------------------ Noah Mendelsohn Voice: 1-617-693-4036 IBM Corporation Fax: 1-617-693-8676 One Rogers Street Cambridge, MA 02142 ------------------------------------------------------------------ Jacek Kopecky <jacek@systinet.com> 01/29/2002 08:06 AM To: Noah Mendelsohn/Cambridge/IBM@Lotus cc: Martin Gudgin <marting@develop.com>, XML Protocol Discussion <xml-dist-app@w3.org> Subject: Re: Section 5 vs Schema Noah, just a minor point: The two examples below are not precisely equivalent: <greeting>Hello</greeting> <salutation>Hello</salutation> <greeting id="0">Hello</greeting> <salutation ref="0" /> That's because in the latter, the values have some relation and if one changes, the other does as well, while in the former example the values are independent. I think you wanted to say that the latter example, while a valid SOAP Encoding graph, is not valid according to the schema provided. Overall, I agree with what you are saying. Best regards, Jacek Kopecky Senior Architect, Systinet (formerly Idoox) http://www.systinet.com/ On Mon, 28 Jan 2002 noah_mendelsohn@us.ibm.com wrote: > Gudge: let me take a stab at the questions that I think you are really > asking. There are several uses the schemas in chapter 4, that should be > distinguished: > > Derivation of simple types > ========================== > > Section 4.2 [1}, for example, illustrates the use of W3C XML Schema to > declare a derived simple type. As noted in [2], I think this may be > appropriate insofar as the schema language is a normative W3C > recommendation, and to clarify the possibility of using the derivation > mechanism provided therein. What I would suggest is the following > additions to the specification: > > * Make clear the validation of such types is optional, and that in the > absence of validation we have a type whose name is known, but with > indeterminate relation to any of the built-in types, and with any content > accepted (simple, complex, mixed, etc. in W3C schema terms). Contents is > checked only when validation is performed. > > * Also make clear that the use of other schema languages to declare types > is acceptable, but that the soap specification mandates no validation for > such languages either. > > * Make clear that when validation wrt/ any schema language is to be > performed, it is the responsibility of the communicating nodes to agree on > the schema language to be used, the schemas to be used, the nature of the > faults to be reflected if validation fails, etc. I believe that such > rules should apply equally to W3C schemas and to others. > > Other Uses of Schemas in Chapter 4 > ================================== > > In section 4.2.1 [3], a schema is offered as a sample to describe the > following instance fragment: > > Sample encoded instance fragment: > <greeting>Hello</greeting> > <salutation>Hello</salutation> > > Sample schema: > <?xml version="1.0" ?> > <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" > xmlns:enc="http://www.w3.org/2001/12/soap-encoding" > > > <xs:import namespace="http://www.w3.org/2001/12/soap-encoding" > /> > > <xs:element name="greeting" type="enc:string" /> > <xs:element name="salutation" type="enc:string" /> > > </xs:schema> > > I agree that this is misleading and inappropriate, and I suspect that is > the true essence of your concern. The schema is basically modeling an XML > tree, whereas the encoding conveys a directed label graph. Using one to > model the other is just inappropriate (and this by the way is one of my > concerns about the current design of WSDL). Indeed, it obscures the whole > point of this section, which is that from the point of view of the > encoding (but not the schema!), the fragment above is equivalent to: > > <greeting id="String-0">Hello</greeting> > <salutation href="#String-0"/> > > Furthermore, as you point out, one of the main reasons to have the > encoding at all is that the data becomes substantially self describing. > While creating a schema for such data is not strictly wrong, I agree that > it does not belong in our specification. > > Bottom line: I think I would restrict examples using W3C XML schema to > cases like the one in section 4.2 as discussed above. > > Thank you very much. > > [1] http://www.w3.org/TR/soap12-part2/#simpletypes > [2] http://lists.w3.org/Archives/Public/xml-dist-app/2002Jan/0378.html > [3] http://www.w3.org/TR/soap12-part2/#stringtypes > > ------------------------------------------------------------------ > Noah Mendelsohn Voice: 1-617-693-4036 > IBM Corporation Fax: 1-617-693-8676 > One Rogers Street > Cambridge, MA 02142 > ------------------------------------------------------------------ > > >
Received on Wednesday, 30 January 2002 15:26:17 UTC