PSI_ESEI_08

Children Element nodes may have zero, one or more children.

Relationship of Nodes Parent Each element and attribute has one parent.

Siblings Nodes that have the same parent.

Ancestors A node's parent, parent's parent, etc.

Descendants A node's children, children's children, etc.

Restrictions on a Set of Values To limit the content of an XML element to a set of acceptable values, we would use the enumeration constraint.

<xs:restriction base="xs:string"> <xs:enumeration value="Audi"/> <xs:enumeration value="Golf"/> <xs:enumeration value="BMW"/> </xs:restriction>

type="carType"/>

<xs:simpleType name="carType">

the type "carType" can be used by other elements

series of numbers or letters that can be used, we would use the pattern constraint.

<xs:restriction base="xs:string"> <xs:pattern value="[a-z]"/>

<xs:pattern value="male|female"/>

The whiteSpace constraint is set to "preserve", which means that the XML processor WILL NOT remove any white space characters:

<xs:whiteSpace value="preserve"/>

The whiteSpace constraint is set to "replace", which means that the XML processor WILL REPLACE all white space characters (line feeds, tabs, spaces, and carriage returns) with spaces:

<xs:whiteSpace value="replace"/>

<xs:length value="8"/>

<xs:minLength value="5"/> <xs:maxLength value="8"/>

Constraint Description enumeration Defines a list of acceptable values fractionDigits Specifies the maximum number of decimal places allowed. Must be equal to or greater than zero length Specifies the exact number of characters or list items allowed. Must be equal to or greater than zero maxExclusive Specifies the upper bounds for numeric values (the value must be less than this value) maxInclusive Specifies the upper bounds for numeric values (the value must be less than or equal to this value) maxLength Specifies the maximum number of characters or list items allowed. Must be equal to or greater than zero minExclusive Specifies the lower bounds for numeric values (the value must be greater than this value) minInclusive Specifies the lower bounds for numeric values (the value must be greater than or equal to this value) minLength Specifies the minimum number of characters or list items allowed. Must be equal to or greater than zero pattern Defines the exact sequence of characters that are acceptable totalDigits Specifies the exact number of digits allowed. Must be greater than zero whiteSpace Specifies how white space (line feeds, tabs, spaces, and carriage returns) is handled

Attributes are optional by default. To specify that the attribute is required, use the "use" attribute: <xs:attribute name="lang" type="xs:string" use="required"/>

The syntax for defining a simple element is: <xs:element name="xxx" type="yyy"/>

built-in data types

xs:string xs:decimal xs:integer xs:boolean xs:date xs:time

A default value is automatically assigned to the element when no other value is specified.

default="red"/

A fixed value is also automatically assigned to the element, and you cannot specify another value.

fixed="red"/

XML Schema became a W3C Recommendation 02. May 2001.

targetNamespace="http://www.w3schools.com" indicates that the elements defined by this schema (note, to, from, heading, body.) come from the "http://www.w3schools.com" namespace.

xmlns:xs="http://www.w3.org/2001/XMLSchema" indicates that the elements and data types used in the schema come from the "http://www.w3.org/2001/XMLSchema" namespace.

prefixed with xs:

xmlns="http://www.w3schools.com" indicates that the default namespace is "http://www.w3schools.com".

Referencing a Schema in an XML Document

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.w3schools.com note.xsd"

This attribute has two values. The first value is the namespace to use. The second value is the location of the XML schema to use for that namespace

You don't have to learn a new language You can use your XML editor to edit your Schema files You can use your XML parser to parse your Schema files You can manipulate your Schema with the XML DOM You can transform your Schema with XSLT

XML Schemas are Extensible

Reuse your Schema in other Schemas Create your own data types derived from the standard types Reference multiple schemas in the same document

Well-Formed is not Enough

<xs:complexType name="fullpersoninfo"> <xs:complexContent> <xs:extension base="personinfo">

<choice> indicator specifies that either one child element or another can occur

The <sequence> indicator specifies that the child elements must appear in a specific order:

Occurrence indicators are used to define how often an element can occur.

For all "Order" and "Group" indicators (any, all, choice, sequence, group name, and group reference) the default value for maxOccurs and minOccurs is 1.

The <maxOccurs> indicator specifies the maximum number of times an element can occur:

The <minOccurs> indicator specifies the minimum number of times an element can occur:

To allow an element to appear an unlimited number of times, use the maxOccurs="unbounded" statement:

Group indicators are used to define related sets of elements.

<xs:group name="groupname">

After you have defined a group, you can reference it in another definition

<xs:group name="persongroup">

<xs:group ref="persongroup"/>

<xs:attributeGroup name="groupname">

<xs:attributeGroup ref="personattrgroup"/>

XML data is stored in plain text format. This provides a software- and hardware-independent way of storing data.

XML Simplifies Data Transport

With XML, data can easily be exchanged between incompatible systems.

Since XML data is stored in plain text format, XML provides a software- and hardware-independent way of sharing data.

XML Simplifies Platform Changes

Large amounts of data must be converted and incompatible data is often lost.

XML Makes Your Data More Available

With XML, your data can be available to all kinds of "reading machines"

XML is Used to Create New Internet Languages

XHTML the latest version of HTML  WSDL for describing available web services WAP and WML as markup languages for handheld devices RSS languages for news feeds RDF and OWL for describing resources and ontology SMIL for describing multimedia for the web 

<note date="12/11/2007">

Entity References

XML Documents Must Have a Root Element

If you place a character like "<" inside an XML element, it will generate an error because the parser interprets it as the start of a new element.

(child elements

< < less than > > greater than & & ampersand  ' ' apostrophe " " quotation mark

XML Attribute Values Must be Quoted

With XML, White Space is Preserved

Comments in XML

<!-- This is a comment -->

no words are reserved.

Best Naming Practices

Make names descriptive

Names should be short and simple

Avoid "-"

Avoid "."

Avoid ":"

use the naming rules of your database for the elements in the XML documents.

Non-English letters

XML elements must follow these naming rules: Names can contain letters, numbers, and other characters Names must not start with a number or punctuation character Names must not start with the letters xml (or XML, or Xml, etc) Names cannot contain spaces

make names descriptive.