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XML Schemas IICIS-189 XML
Qualification refers to whether a value (element, attribute) must be qualified by a its namespace◦ When an element (or attribute) doesn’t have a
namespace declaration it’s unqualified◦ Determines how name is used in data (instance)
document A schema has the attributes
elementFormDefault and attributeFormDefault◦ Set to qualified or unqualified◦ By setting to qualified, must include a namespace
when use attributes or elements
Qualification
<schema attiributeFormDefault=“unqualified” elementFormDefault=“unqualified”>
Element and attributes can be specified individually as qualified (or not)<element form=“unqualified”><attribute form=“qualified”>
Qualification Examples
Have several different ways to specify how elements fit together
Sequence: specifies that elements must be in order, and there’s variability in when and how many times a child element occurs
All: elements may appear (or not), and in any order
Choice: one of several child elements may appear
Group: a set of elements may be referenced by name
Content Models
Allows elements to appear in any order or not at all
Rules governing use1. Must be only content model declaration of a
<complexType> definition For example, can’t follow with <sequence>
2. Can only have element declarations as children3. The children of the <all> element may appear
once – or not at all
<all> Declaration
<element name=“name”><complexType>
<all><element name=“first”
type=“xs:string” /><element name=“middle”
type=“xs:string” /><element name=“last”
type=“xs:string” /></all>
</complextType></element>
<all> Example
Similar in syntax to sequence Only one member of list can appear in the
document Allow a middle initial or a middle name
<choice><element name=“middleInitial” type=“xs:string” /><element name=“middleName type=“xs:string” />
</choice>
Note: Best case would restrict Middle Initial to one character with a simple type.
Choice
A group allows you to tie elements together, and then reference then with a single name
Definition:<group name=“nameFields”>
<element name=“first” type=“xs:string” /><element name=“middle” type=“xs:string” /><element name=“last” type=“xs:string” />
</group>Use:<element name=“name”>
<complexType><group ref=“nameFields” />
</complexType></element>
Element Groups
Can create a group of attributes similar to element groups
Allows re-use of common members without multiple definitions◦ Attribute groups cannot be recursive (refer to
themselves
Attribute Groups
Create limits on acceptable values as a simple type
A facet is a single property or trait of a simple type
Twelve facets can be applied to limit acceptable values
Restriction
minExclusive: smallest value, excluding what’s specified
minInclusive: smallest value, including what’s specified
maxExclusive: largest value, excluding what’s specified
maxInclusive: largest value, including what’s specified
totalDigits: total number of digits of a numeric type
Restriction Facets
fractionDigits: number of decimal places length: number of items in a list or characters
in a string minLength: minimum number of list items or
characters maxLength: maximum number of list items or
characters enumeration: specify member of a list whitespace: how whitespace should be treated pattern: restrict string types by pattern
Facets – 2
Specifying a positive integer<xs:simpleType name="creditHours">
<xs:restriction base="xs:integer"><xs:minInclusive value="0" />
</xs:restriction></xs:simpleType>
Sample Restrictions – 1
Specifying a list:<xs:simpleType name="cisDepartments">
<xs:restriction base="xs:string"><xs:enumeration value="CIS" /><xs:enumeration value="CNA" /><xs:enumeration value="CS" />
</xs:restriction></xs:simpleType>
Sample Restrictions – 2
Specify a 3 digit value
<xs:simpleType name="courseNumbering"><xs:restriction base="xs:string">
<xs:pattern value="\b[0-9]{3}\b" /></xs:restriction>
</xs:simpleType>
Sample Restrictions – 3
<?xml version="1.0" encoding="utf-8"?><xs:schema targetNamespace="http://tempuri.org/XMLSchema.xsd" elementFormDefault="qualified" xmlns="http://tempuri.org/XMLSchema.xsd" xmlns:mstns="http://tempuri.org/XMLSchema.xsd" xmlns:xs="http://www.w3.org/2001/XMLSchema”> <xs:element name="course"> <xs:complexType> <xs:sequence> <xs:element name="department" type="cisDepartments" /> <xs:element name="number" type="courseNumbering" /> <xs:element name="title" type="xs:string" /> <xs:element name="credits" type="creditHours" /> </xs:sequence> </xs:complexType> </xs:element>
Sample Course Schema Part 1
<xs:simpleType name="creditHours"> <xs:restriction base="xs:integer"> <xs:minInclusive value="0" /> </xs:restriction> </xs:simpleType> <xs:simpleType name="cisDepartments"> <xs:restriction base="xs:string"> <xs:enumeration value="CIS" /> <xs:enumeration value="CNA" /> <xs:enumeration value="CS" /> </xs:restriction> </xs:simpleType> <xs:simpleType name="courseNumbering"> <xs:restriction base="xs:string"> <xs:pattern value="\b[0-9]{3}\b" /> </xs:restriction> </xs:simpleType> </xs:schema>
Sample Part 2
A list allows an element or attribute to store multiple values◦ Uses enumerated values◦ Values are separated by whitespace, so
whitespace cannot be part of the content◦ Can be built-in XML or a defined simpleType data
type
<list> Declarations
<simpleType name=“Degrees”><restriction base=“string”><enumeration value=“AA” /><enumeration value=“AS” /><enumeration value=“AAS” /></restriction>
</simpleType>
<simpleType name=“DegreesList”><list itemType=“Degrees”/>
</simpleType>
<element name=“degreesEarned” type=“DegreesList” />
<list> ExampleDefine different values
Define data type using values
Define element storing different values
<union> allows the combination of two data type for an element or attribute
If have a possiblePoints element, expected value would be an integer; <union> would allow a string entry to note a “Missing” value
Separate data types with whitespace
<simpleType name=“CreditValue”><union memberTypes=“xs:integer
xs:string /></simpleType
<union> Declarations
<xs:simpleType name="zipCode"> <xs:union> <xs:simpleType> <xs:restriction base="xs:string"> <xs:pattern value="[0-9]{5}" /> </xs:restriction> </xs:simpleType> <xs:simpleType> <xs:restriction base="xs:string"> <xs:pattern value="[0-9]{5}-[0-9]{4}" /> </xs:restriction> </xs:simpleType> </xs:union> </xs:simpleType>
<union> (continued)
