Schema and Schema XML Representation

This section describes what is a schema and what is a schema XML representation.

What is a schema? A schema is a container for schema components that defines a set of rules to which an XML document must conform in order to be considered 'valid' according to that schema. There are 7 types of schema components that mentioned in the XML Schema specification:

A schema can be represented in XML by one or more schema documents, commonly called XSD (XML Schema Definition) documents

In another word, a schema XML document, XSD file, may contain one complete schema, or a part of one schema.

For example, the following XML document, hello.xsd, is the XML representation, XSD document, of a schema which contains only 1 component, an element declaration component that defines a validation rule for the XML document to be validated.

<?xml version="1.0"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
 <xsd:element name="p" type="xsd:string"/>
</xsd:schema>

Apparently, the validation rule defined in hello.xsd says that the XML document to be validated can have a root element named as "p" with no attributes and no sub (child) elements. But it can have a "string" as its text content.

Base this concept, the more technically correct definition of an XSD document should be:

What is an XSD document? An XSD document is the XML representation of an XML schema, or a part of an XML schema, expressed in XML Schema language.

Last update: 2013.

Table of Contents

 About This Book

 Introduction to XML Schema

 XML Editor and Schema Processor - XMLPad

 Java API for XML Processing - JAXP

 JAXP - XML Schema (XSD) Validation

 Xerces2 Java Parser - Java API of XML Parsers

 Using Xerces2 Java API

XML Schema Language - Basics

Schema and Schema XML Representation

 Checking Schema Documents - XsdSchemaChecker.java

 Creating Schema Documents - "schema" Element

 Declaring Root Elements - "element" Element

 Specifying Element Datatype - "type" Attribute

 Using XML Schema Built-in Datatypes

 Using XML Schema Built-in Datatypes Incorrectly

 Validating XML Documents against Schema Documents

 Deriving New Simple Datatypes - "simpleType" Element

 Defining Complex Datatypes - "complexType" Element

 Validation Error Examples on Complex Datatypes

 Introduction of XSD Built-in Datatypes

 "string" and Its Derived Datatypes

 "decimal" and Its Derived Datatypes

 "dateTime" and Its Related Datatypes

 Miscellaneous Built-in Datatypes

 Facets, Constraining Facets and Restriction Datatypes

 "simpleType" - Defining Your Own Simple Datatypes

 Complex Element Declaration

 Identity-Constraints: unique, key and keyref

 Assertion as Custom Validation Rules

 XML Schema Location and Namespace in XML Documents

 Overriding Element Types in XML Documents

 Linking Multiple Schema Documents Together

 Glossary

 References

 PDF Printing Version