[DFDL-WG] DFDL & support for XML Schema 1.1

Wed Oct 29 09:08:43 CDT 2008

Here's excerpts from the latest XML Schema 1.1 draft 
(http://www.w3.org/TR/xmlschema11-1/)

XML Representation Summary: all Element Information Item et al.
<all
  id = ID
  maxOccurs = 1 : 1
  minOccurs = (0 | 1) : 1
  {any attributes with non-schema namespace . . .}>
  Content: (annotation?, (element | any)*)
</all>
<choice
  id = ID
  maxOccurs = (nonNegativeInteger | unbounded)  : 1
  minOccurs = nonNegativeInteger : 1
  {any attributes with non-schema namespace . . .}>
  Content: (annotation?, (element | group | choice | sequence | any)*)
</choice>
<sequence
  id = ID
  maxOccurs = (nonNegativeInteger | unbounded)  : 1
  minOccurs = nonNegativeInteger : 1
  {any attributes with non-schema namespace . . .}>
  Content: (annotation?, (element | group | choice | sequence | any)*)
</sequence>

Schema Component Constraint: All Group Limited
When a model group has {compositor} all, then all of the following must be 
true: 
1 It appears only as the value of one or both of the following properties: 

1.1 the {model group} property of a model group definition.
1.2 the {term} property of a Particle with {max occurs}=1which is the 
{particle} of the {content type} of a complex type definition.

So xs:all:
- can contain elements as content (as 1.0)
- can contain wildcards as content (new)
- can't contain model groups as content (as 1.0) 
- content can repeat (new)
- can be the content of a model group definition
- can be the content of a complex type
- can't be the content of a model group  **

These rules prevent:
a) xs:choice or xs:sequence directly inside xs:all
b) xs:all directly inside xs:sequence or xs:choice
Clearly wrappering in an element solves this but b) can also be solved by 
using an xs:group reference.

On input: I agree that the infoset items emitted for xs:all content will 
appear in the order of the physical data
On output: I think that the order of infoset items preented for xs:all 
content should appear in the order presented

Sandy also made the point that because we are choosing an XML Schema 
subset for DFDL, we are at liberty to choose which of the 1.1 enhancements 
we adopt.

Regards

Steve Hanson
Programming Model Architect
WebSphere Message Brokers
Hursley, UK
Internet: smh at uk.ibm.com
Phone (+44)/(0) 1962-815848

"Mike Beckerle" <mbeckerle.dfdl at gmail.com> 
29/10/2008 13:13
Please respond to
<mbeckerle.dfdl at gmail.com>

To
Steve Hanson/UK/IBM at IBMGB, <dfdl-wg at ogf.org>
cc

Subject
RE: [DFDL-WG] DFDL & support for XML Schema 1.1

Very good.

If these are the primary things in Schema 1.1, then this is a big help.

Question: if we drop unordered property so that we have xsd:sequence 
groups and xsd:all groups, will we retain restrictions on nesting, i.e., 
can't nest xsd:all inside an xsd:all, etc.

To me there's little or no downside to these restrictions because you can 
always put an element "wrapper" around an xsd:all group which changes the 
logical model, but in DFDL doesn't imply anything about the physical 
representation, so it's not really a problem. 

I assume xsd:all will have the semantics of preserving the arrival order, 
so it is much like an array of choice semantically. That is, the DFDL 
infoset will have the items within the xsd:all group in the order they 
appear in the physical data.

Mike Beckerle | OGF DFDL WG Co-Chair | CTO | Oco, Inc.
Tel:  781-810-2100  | 504 Totten Pond Road, Waltham MA 02451 | 
mbeckerle.dfdl at gmail.com 

From: dfdl-wg-bounces at ogf.org [mailto:dfdl-wg-bounces at ogf.org] On Behalf 
Of Steve Hanson
Sent: Wednesday, October 29, 2008 7:54 AM
To: dfdl-wg at ogf.org
Subject: [DFDL-WG] DFDL & support for XML Schema 1.1

Sandy Gao at IBM has looked at the reasons for moving to schema 1.1 and 
concluded that DFDL should move. 

Grounds: 
- Weakened wildcard support - there is less ambiguity in 1.1 because an 
optional element x followed by a wildcard will match x, instead of giving 
a UPA error - this will enable DFDL to model more formats 
- Relaxation of <xs:all> means that it is suitable for DFDL use - this 
will allow us to drop the dfdl:unordered property 
- In Schema 1.0, annotations are lost on particles, but they are needed by 
DFDL. Schema 1.1 captures all annotations. 

Regards

Steve Hanson
Programming Model Architect
WebSphere Message Brokers
Hursley, UK
Internet: smh at uk.ibm.com
Phone (+44)/(0) 1962-815848 

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