http://2006.xmlconference.org/programme/presentations/43.html

1. W3C XML Schema
Patterns for Databinding
Paul Downey, BT
Chair, XML Schema Patterns for Databinding Working Group
XML 2006, December 5th 2006

2. XML Schema
?

3. Validation
XML
Schema
Post
XML Schema Schema
Instance Validation
Processor Infoset

4. Description
XML
Schema
XML
Sender Instance
Receiver

5. Types
xs:string
xs:int
XML
tns:Address
foo:PurchaseOrder

6. Databinding
?

7. Databinding
Abstraction
Model XML

8. Model
• Java
• Database
• Annotated DOM
• JSON
• PHP serialisation
• XML
• Whatever

9. Why Describe
?

10. Duck Typing XML
?

11. Force Array
<opt> {
<name>value</name> name => ‘value’
</opt> }
{
<opt> name => [
<name>value1</name> ‘value1’,
<name>value2</name> ‘value2’
</opt> ]
}

12. Static Typing
{
int accountNo;
long ammount;
string name;
}

13. What’s wrong with
Databinding
?

14. “State of the Art”
• reject valid XML Schema documents
• reject valid XML instance documents
• content of valid XML instance documents
often unavailable in model

15. Impedance
Mismatch
><
OO

16. Circles, Triangles,
Rectangles
XML 2003
http://www.idealliance.org/papers/dx_xml03/papers/06-02-01/06-02-01.html

17. I ! Mixed Content
text <O/> text
<O> text </O>

18. Don’t Databind?
• XSLT
• DOM
• LINQ
• E4X
• XJ
• etc

19. Abstraction Scale
Objects Infoset XML Bits
Typed DOM Text
DOM
Templating

20. They Don’t Like
XML!

21. Abstraction
?

22. XML Schema
is Big ..
• Lot’s of ways to describe the concrete
• Lot’s of ways to represent the abstract

23. Partial
Implementations
“Our tool doesn’t support xs:foo.
Change your schema.”
* vendor

24. So begins ..
“The Barf Dance”

25. it’s not so much that
schema sucks ...

26. or that databinding tools
suck ...

27. it’s that all databinding tools
suck
differently

28. W3C
Working Group
?

29. WS-I
• Basic Profile
• XML Schema Work Plan Working Group

30. W3C Workshop
XML Schema 1.0 User Experiences

31. Discussion

32. Don’t Just Change
Schema!
… 300,000+ developers use XSD
… There is tremendous value in
XML Schema. Don't just change it…
Soumitra Sengupta,
Microsoft

33. Discussion Topics
• versioning
• profiles and patterns of use
• code generation (v) validation
• Unique Particle Attribution (UPA)
• XML Schema 1.1
• test suite

34. W3C XML Schema
Patterns for Databinding
Working Group
!

35. Deliverables
• W3C Recommendation for Basic Patterns
• W3C Recommendation for Advanced Patterns
• Test Suite
• Mechanism to Detect patterns

36. Out of Scope:
• Profile of Schema
• Language Specific Detail

37. Patterns
!

38. AnyURIElement
.//xs:element/@type[resolve-QName(.,..)
= xs:QName('xs:anyURI')]
<xs:element name=quot;anyURIElementquot;
type=quot;xs:anyURIquot; />
http://www.w3.org/2002/ws/databinding/patterns/6/09/AnyURIElement

39. ElementMinOccurs0
MaxOccursUnbounded
.//xs:element[@minOccurs = '0'
and @maxOccurs = 'unbounded']/
(@minOccurs, @maxOccurs)
http://www.w3.org/2002/ws/databinding/patterns/6/09/ElementMinOccurs0MaxOccursUnbounded

40. SequenceSingle
RepeatedElement
.//xs:sequence[count(xs:element) = 1]/
xs:element[@maxOccurs = 'unbounded']/
(., @maxOccurs)
Overlapping!
http://www.w3.org/2002/ws/databinding/patterns/6/09/SequenceSingleRepeatedElement

41. StringEnumerationType
.//xs:simpleType/xs:restriction[
@base/resolve-QName(.,..) = xs:QName('xs:string')
and xs:enumeration]/
(., @base, xs:enumeration/(., @value))
<xs:simpleType name=quot;Beatlequot;>
<xs:restriction base=quot;xs:stringquot;>
<xs:enumeration value=quot;Johnquot; />
<xs:enumeration value=quot;Paulquot; />
<xs:enumeration value=quot;Georgequot; />
<xs:enumeration value=quot;Ringoquot; />
</xs:restriction>
http://www.w3.org/2002/ws/databinding/patterns/6/09/StringEnumerationType

42. SOAP Encoded Array
./xs:complexType[@name]/xs:complexContent/
xs:restriction[
@base/resolve-QName(.,..)
= xs:QName ('soap11enc:Array')]/
xs:attribute[(@ref/resolve-QName(.,..)
= xs:QName('soap11enc:arrayType'))
and @wsdl11:arrayType]/
(../.., ../(., @base), ., @ref, @wsdl11:arrayType)
http://www.w3.org/2002/ws/databinding/patterns/6/09/SOAPEncodedArray

43. Palatability
?

44. Value Judgement
• xs:any becomes XMLElement
• xs:anyURI becomes String
• xs:decimal becomes String

45. Examples
!

46. ElementMinOccurs0
MaxOccursUnbounded
<xs:element name=quot;durationListquot; type=quot;ex:DurationListquot; />
<xs:complexType name=quot;DurationListquot;>
<xs:sequence>
<xs:element name=quot;durationValuequot; type=quot;xs:shortquot;
! ! ! ! ! minOccurs=quot;0quot; maxOccurs=quot;unboundedquot; />
</xs:sequence>
</xs:complexType>
http://www.w3.org/2002/ws/databinding/examples/6/09/ElementMinOccurs0MaxOccursUnbounded

47. Example
Descriptions
• ComplexTypeSequenceExtension.xsd
• echoComplexTypeSequenceExtension.xsd
• echoComplexTypeSequenceExtension.wsdl
• echoComplexTypeSequenceExtension-wsdl20.wsdl

48. Example
Instances
• ElementMinOccurs0MaxOccursUnbounded-01.xml
• echoElementMinOccurs0MaxOccursUnbounded-01.xml
• echoElementMinOccurs0MaxOccursUnbounded-01-soap11.xml
• echoElementMinOccurs0MaxOccursUnbounded-01-soap12.xml

49. Test Suite
Example
Description
Instance
Model
Toolkit
Output

50. Test
Reports

51. Patterns Detector
!

52. Patterns Detector
XML Patterns
Schema
Detector (URIs)

55. Buckets
!

56. Basic Patterns
• known to work with “state of the art”
implementations
• they’re, um, very Basic
Publishers of Schemas Take Note!

57. TargetNamespace
.[@targetNamespace]/
(., @targetNamespace)
An [XML Schema 1.0] document conforming to this
specification MUST define a targetNamespace whose
value is an absolute URI. †
http://www.w3.org/2002/ws/databinding/patterns/6/09/TargetNamespace

58. “State of the Art”
?

59. SLIPPERY
SLOPE

60. Value Judgement
• new tools arrive
• old tools become defunct
• some tools are very lame
• we can’t test every tool
“Bring out your implementations”

61. Advanced Patterns
• exhibited by real schemata
• they’re, um, not very interoperable
Developers of Implementations Take Note!

62. Not Advanced
?

63. SLIPPERY
SLOPE

64. Value Judgement
• XML Schema is big
• Coverage or Possible to Databind?
• always another Schema
“Bring out your schemata”

65. Patterns in the
Wild

66. Build Your Own
Bucket
• List Patterns your schemas use
• List Patterns your toolkit supports
• Analyse schemas “in the wild”

67. Other Topics
?

68. Document
Conformance
Implementation
Conformance

69. WS-I Basic Profile
• Detector works on WSDL 1.1
• Composable with Basic Profile 1.1

70. Annotations
• Tools Generate them
• Useful for “round tripping”
• No-one is submitting them

71. Versioning
• Concrete patterns exist
• They’re all Advanced
XML Schema 1.1 is the answer?

72. Progress
?

73. Schedule

74. Participants
• BT
• Health Level 7
• National Association of Convenience Stores (NACS)
• Origo Services Limited
• SAP AG
• WSO2
• Invited Expert: Priscilla Walmsley
... and that’s It!

76. We Need Your
Help!
www.w3.org/2002/ws/databinding

77. How You Can Help
• Participate in the Working Group
• Encourage your vendor of choice to participate
• Contribute to the test suite
• Contribute your Schemata
www.w3.org/2002/ws/databinding

78. Thank you!
Any Questions
?
www.w3.org/2002/ws/databinding