XML Schema
PB138
What is XML Schema
● XML document
<xs:schema xmlns:xs="http://www.w3.
org/2001/XMLSchema"
>
How to validate
● Use example people.xsd to validate people.
xml
xmllint --schema mySchema.xsd neco.xml
Basic XML Schema assigns types
<xs:element name=”XXX” type=”YYY” />
Basic builtin types
● Type “xs:string”
● Type “xs:anyType”
Basic XML Schema assigns types
<xs:element name=”XXX” type=”YYY” />
Create an xsd that validates, that people.xml
has root element “name”
How to write schema
1. Define data types
2. Assign data types to nodes
Defining Data Types
● Nodes in XML have data types
● Attrs or Elements may be of Simple Type
<xs:simpleType
○ contain only text
○ contain numbers
○ contain regex restrictioned
● Element may be of Complex Type <xs:
complexType
○ contain other elements
○ contain attributes
○ contain text
Defining Data Types
<xs:complexType name=”XXXXX”>
Data type of element with elements
<xs:complexType name=”XXX”>
<xs:sequence minOccurs=”X”
maxOccurs=”Y”>
● all
● choice
How to define “any element”
<xs:complexType name=”XXX”>
<xs:sequence minOccurs=”X”
maxOccurs=”Y”>
<xs:any processContents="skip"/>
Complex Types
● <xs:complexType name="....">
● may contain sequence of elements (all,
choice....)
○ minOccurs
○ maxOccurs
● After the sequence, all, choice you can
declare attrs:
<xs:attribute name="name"
type="xs:string"/>
Simple Types
● We may specify precisely by inheritance
○ name is special type of string
○ date is special type of string
○ positive integer is special type of string
<xs:simpleType name=”XXX”>
<xs:restriction base="xs:string>
......
Simple Types Enumeration
<xs:simpleType name=”XXX”>
<xs:restriction base="xs:string>
<xs:enumeration value="xyz"/>
Simple Types Enumeration
● Create an enumeration for phone codes:
“+421; +420”
Enrich People XML and write XSD
● Add attribute BirthDate with regex format
“MM-DD-YYYY”
● Write XSD schema for people.xml
Elements just with Attributes
● Complex type, simple content
<xs:complexType>
<xs:simpleContent>
<xs:extension base="xs:string">
<xs:attribute
<xs:attribute
Elements just with Attributes
● Finish schema for <phone>
Must be inside <xs:element>!
<xs:element name="people" >
<xs:unique name="myUniq">
<xs:selector xpath="./ns:person"/>
<xs:field xpath="@id"/>
<xs:field xpath="xxxx"/>
</xs:unique>
...
xs:unique
Must be inside <xs:element>!
<xs:element name="people" >
<xs:key name="myPk">
<xs:selector xpath="./ns:person"/>
<xs:field xpath="@id"/>
<xs:field xpath="xxxx"/>
</xs:key>
...
xs:key
xs:keyref
<xs:keyref name="parentId"
refer="myPk">
<xs:selector xpath="./ns:person"/>
<xs:field xpath="@parentId"/>
...
What else is XML schema?
● Namespaces
● Defining uniqueness (we need XPath)
● Element/Attribute groups
● Unions
● References
● Includes/Imports
● Annotations