XML Schema

1
XML Schema

• Matthias Hauswirth

2
Agenda

• W3C Process
• XML Schema Requirements
• The Specifications
• Schema Tools

3
The W3C Process
Proposals
Proposals
Others
Working Draft
Candidate Recommendation
Technical Reports (TR)
Working Group
Proposed Recommendation
Recommendation
Note
4
XML Schema Status
DCD
XML-Data
SOX
DDML
Others
Working Drafts (Part 0, 1, 2)
Candidate Recommendation
Technical Reports (TR)
Schema Working Group
Proposed Recommendation
Recommendation
Requirements
5
XML Schema Requirements

• Structural
• namespaces
• primitive types structural schema integration
• inheritance
• Data type
• integers, dates, (like in languages)
• user-defined (constrain some properties)
• Conformance
• processors, validity

6
Design Principles

• More expressive than DTDs
• Expressed in XML
• Self-describing
• Usable by various XML applications
• Simple enough

7
The Specifications

• Part 0 Primer
• non-normative introduction
• Part 1 Structures
• define structure
• constraining contents
• Part 2 Datatypes
• specify datatypes on elements and attributes

8
An Example Document (1/2)

• lt?xml version1.0?gt
• ltpurchaseOrder orderDate1999-10-20gt
• ltshipTo countryUSgt
• ltnamegtMatthias Hauswirthlt/namegt
• ltstreetgt4500 Brookfield Dr.lt/streetgt
• ltcitygtBoulderlt/citygt
• ltstategtCOlt/stategt
• ltzipgt80303lt/zipgt
• lt/shipTogt
• ltbillTo countryUSgt
• ltnamegtBrian Templelt/namegt
• ltstreetgt1234 Strasselt/streetgt
• ltcitygtBoulderlt/citygt
• ltstategtCOlt/stategt
• ltzipgt80302lt/zipgt
• lt/billTogt
• ...

9
An Example Document (2/2)

• ltcommentgtBrian payslt/commentgt
• ltitemsgt
• ltitem partNum123-ABgt
• ltproductNamegtPorschelt/productNamegt
• ltquantitygt1lt/quantitygt
• ltpricegt129400.00lt/pricegt
• ltcommentgtNeed a new onelt/commentgt
• lt/itemgt
• ltitemgt
• ltproductNamegtFerrarilt/productNamegt
• ltquantitygt2lt/quantitygt
• ltpricegt189000.25lt/pricegt
• ltshipDategt1999-05-21lt/shipDategt
• lt/itemgt
• lt/itemsgt
• lt/purchaseOrdergt

10
An Example Schema (1/3)

• ltxsdschema xmlnsxsdhttp//www.w3.org/1999/XMLS
  chemagt
• ltxsdelement namepurchaseOrder
  typepurchaseOrderType/gt
• ltxsdelement namecomment typexsdstring/gt
• ltxsdcomplexType namePurchaseOrderTypegt
• ltxsdelement nameshipTo typeAddressType/gt
• ltxsdelement namebillTo typeAddressType/gt
• ltxsdelement refcomment minOccurs0/gt
• ltxsdelement nameitems typeItemsType/gt
• ltxsdattribute nameorderDate
  typexsddate/gt
• lt/xsdcomplexTypegt
• ...

11
An Example Schema (2/3)

• ltxsdcomplexType nameAddressTypegt
• ltxsdelement namename typexsdstring/gt
• ltxsdelement namestreet typexsdstring/gt
• ltxsdelement namecity typexsdstring/gt
• ltxsdelement namestate typexsdstring/gt
• ltxsdelement namezip typexsddecimal/gt
• ltxsdattribute namecountry
  typexsdNMTOKEN
• usefixed valueUS/gt
• lt/xsdcomplexTypegt
• ltxsdsimpleType nameSkuType
  basexsdstringgt
• ltxsdpattern value\d3-A-Z2/gt
• lt/xsdsimpleTypegt
• ...

12
An Example Schema (3/3)

• ltxsdcomplexType nameItemsTypegt
• ltxsdelement nameitem minOccurs0
  maxOccursunboundedgt
• ltxsdcomplexTypegt
• ltxsdelement nameproductName
  typexsdstring/gt
• ltxsdelement namequantitygt
• ltxsdsimpleType basexsdpositiveIntegergt
• ltxsdmaxExclusive Value100/gt
• lt/xsdsimpleTypegt
• lt/xsdelementgt
• ltxsdelement nameprice typexsddecimal/gt
  
• ltxsdelement refcomment minOccurs0/gt
• ltxsdelement nameshipDate typexsddate
  minOccurs0/gt
• ltxsdattribute namepartNum
  typeSkuType/gt
• lt/xsdcomplexTypegt
• lt/xsdelementgt
• lt/xsdcomplexTypegt
• lt/xsdschemagt

13
Part 1 Structures

• Type Definitions ltsimpleTypegt ltcomplexTypegtlteleme
  ntgt ltgroupgt ltallgt ltchoicegt ltsequencegtltattributegt
  ltattributeGroupgt
• Attribute Declarations ltattributegtltsimpleTypegt
• Element Declarations ltelementgtltsimpleTypegt
  ltcomplexTypegt
• Attribute Group Definitions ltattributeGroupgtltattr
  ibutegt ltattributeGroupgt
• Model Group Definitions ltgroupgtltelementgt ltgroupgt
  ltallgt ltchoicegt ltsequencegt
• Notation Declarations ltnotationgt
• Annotations ltannotationgtltappinfogt ltdocumentationgt

14
DTD vs. Schema Structure

• DTD
• lt!ELEMENT e1 ((e2,e3?)e4)gt

• Schema
• ltelement namee1gt
• ltcomplexTypegt
• ltchoicegt
• ltsequence maxOccursunboundedgt
• ltelement refe2/gt
• ltelement refe3 minOccurs0/gt
• lt/sequencegt
• ltelement refe4gt
• lt/choicegt
• lt/complexTypegt
• lt/elementgt

15
Referential/Uniqueness Integrity

• Define Constraints using XPath expressions
• ltuniquegt
• ltkeygt
• ltkeyrefgt
• ltselectorgt
• ltfieldgt

16
Part 2 Datatypes ltsimpleTypegt

• Value Space
• defined axiomatically (primitive types)
• enumerated outright
• defined by restricting value space of other type
• combination of values of other type (list)
• has certain properties (e.g. cardinality,
  equality, ordered)
• Lexical Space
• set of literals for a type (e.g. 100 and 1.0E2
  denote same value)
• Facets
• fundamental facets (define the type)
• constraining facets (allow to constrain the value
  space)

17
Fundamental Facets

• Fundamental facets cant be changed
• Equal
• all types provide an equality relation
• Order
• some types provide an ordering relation
• Bounds
• upper bound and lower bound
• Cardinality
• finite, infinite
• Numeric
• yes or no

18
Constraining Facets

• length
• minLength
• maxLength
• pattern
• enumeration
• maxInclusive / maxExclusive
• minInclusive / minExclusive

• precision
• scale
• encoding
• duration
• period

19
Primitive vs. Derived Types

• Primitive Types
• string
• boolean
• float
• double
• decimal
• timeDuration
• recurringDuration
• binary
• uriReference
• ID
• IDREF
• ENTITY
• NOTATION
• QName
• exist ab initio

• Derived Type
• by restriction
• use constraining facets
• ltsimpleType namesku basexsdstringgt
• ltpattern
• value\d3-A-D4/gt
• lt/simpleTypegt
• by list
• next slide

20
Built-in vs. User-Derived Types

• Built-in types
• primitive
• derived
• language
• IDREFS
• long
• int
• short
• positiveInteger
• time
• month
• recurringDay
• ...

• User-derived types
• derived-only

21
Atomic vs. List Types

• Atomic
• values indivisible
• ltsimpleType nameShoeSize basexsddecimal/gt
• ltelement nameshoe typeShoeSize/gt
• ltshoegt10.5lt/shoegt

• List
• sequence of values of atomic type
• ltsimpleType nameShoeSizes baseshoeSize
  derivedBylist/gt
• ltelement nameshoes typeShoeSizes/gt
• ltshoesgt8 10 10.5lt/shoesgt

22
Tools

• XML Schema-aware Parser
• Xerces-J
• Oracle XML Schema Processor
• XML Schema Validator (XSV, online)
• DTD to Schema Conversion Tools
• XML Schema Editor
• Extensibilitys XML Authority
• XML Schema-aware Instance Editor
• Extensibilitys XMLInstance
• ChannelPoints Merlot (maybe in future)