XML and XHTML Content Versus Appearance

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XML AND XHTMLContent Versus Appearance



XML Basics

XML is the basic building block of Web services. All the Web

services technologies specified by the WS-I Basic Profile 1.0are built on XML and the W3C XML Schema Language.

The extensible Markup Language (XML) is a meta-language

or a language for defining other languages defined by aspecification.



XML Address Document<?xml version="1.0" encoding="UTF-8" ?>

<addresses>

<address category="friend">

<name>Bill Frankenfiller</name> <street>3243 West 1st Ave.</street>

<city>Madison</city> <state>WI</state> <zip>53591</zip>

</address>

<address category="business">

<name>Amazon.com</name>

<street>1516 2nd Ave</street>

<city>Seattle</city> <state>WA</state> <zip>90952</zip></address>

</addresses>



Widescreen Graphics

XML Document Instance

<?xml version="1.0" encoding="UTF-8" ?>

<address><name>Amazon.com</name>


<city>Seattle</city>

<state>WA</state>

<zip>90952</zip></address>



XML Declaration

Elements Attributes

Empty-Element Tag in XML

Comments CDATA Section



<?xml version="1.0" encoding="UTF-8" ?>



<address category="business" >



<city>Seattle</city>

<state>WA</state>

<zip>90952</zip>

<note><![CDATA[ <html><body><p>Last time I contacted <b> text <body></html>

]]>

</note>

</address>



Processing XML Documents

XML parser

parsers read a stream of data (usually a file or networkstream) and break it down into functional units that can

then be processed by a software application.

basically two standard kinds of XML parser APIs: SAX

and DOM.




SAX (Simple API for XML)

first standard XML parser API and is very popular.Although several individuals created it, David Brownellcurrently maintains SAX2, the latest version, as anopen development project at SourceForge.org. SAX2parsers are available in many programminglanguages including Java. SAX2 is based on an eventmodel.




DOM (Document Object Model

was developed after SAX2 and maintained by the W3C. DOMlevel 2 (DOM 2) is the current version, but there is a DOM level3 in the works. DOM 2 parsers are also available for manyprogramming languages, including Java. DOM 2 presents theprogrammer with a generic, object-oriented model of an XML

document. Elements, attributes, and text values are representedas objects organized into a hierarchical tree structure thatreflects the hierarchy of the XML document being processed



XML Namespaces

An XML namespace provides a qualified name for an

XML element or attribute



XML Namespaces<?xml version="1.0" encoding="UTF-8" ?>

<purchaseOrder orderDate="2003-09-22µ xmlns="http://www.Monson-Haefel.com/jwsbook/PO">

<accountName>Amazon.com</accountName>

<accountNumber>923</accountNumber>

<address xmlns="http://www.Monson-Haefel.com/jwsbook/ADDR">

<name>AMAZON.COM</name>

<street>1850 Mercer Drive</street>

<city>Lexington</city>

<state>KY</state>

<zip>40511</zip>

</address>

<book> <title>J2EE Web Services</title> <quantity>300</quantity> <wholesale-

price>29.99</wholesale-price> </book>

<total>8997.00</total>

</purchaseOrder>



XML Namespaces

Default Namespaces

The xmlns declarations made in last example defined the default

namespace for the element and all its descendants. The scope of adefault namespace applies only to the element and its descendants, sothe xmlns used in the address element applies only to the address,name, street, city, state, and zip elements. The default xmlns declared inthe purchaseOrder element applies to all the elements except theaddress elements, because the address element overrides the default

namespace of the purchaseOrder element to define its own defaultnamespace.



XML Namespaces

Prefixes

You can assign an XML namespace to a prefix, then usethat prefix to fully qualify each element name.



XML Namespaces<?xml version="1.0" encoding="UTF-8" ?>

<po:purchaseOrder orderDate="2003-09-22´ xmlns:po="http://www.Monson-Haefel.com/jwsbook/POµxmlns:addr="http://www.Monson-Haefel.com/jwsbook/ADDR">

<po:accountName>Amazon.com</po:accountName>

<po:accountNumber>923</po:accountNumber>

<addr:address>

<addr:name>AMAZON.COM</addr:name>

<addr:street>1850 Mercer Drive</addr:street>

<addr:city>Lexington</addr:city>

<addr:state>KY</addr:state>

<addr:zip>40511</addr:zip>

</addr:address>

<po:book>

<po:title>J2EE Web Services</po:title>

<po:quantity>300</po:quantity>

<po:wholesale-price>29.99</po:wholesale-price>

</po:book>

<po:total>8997.00</po:total>



XML Namespaces

XML namespaces based on URLs tend to be universally

unique, which makes it easy for parsers and softwareapplications to distinguish between instances of

different markup languages within the same document.

Namespaces help avoid name collisions, where two

elements from different markups share a common localname.



Avoiding Element Name Collisions<?xml version="1.0" encoding="UTF-8" ?>

<definitions name="Address-Updateµ targetNamespace="http://www.monson-haefel.org/jwsbook/Address-Update"

xmlns:tns="http://www.monson-haefel.org/jwsbook/Address-Update"

xmlns:addr="http://www.Monson-Haefel.com/jwsbook/ADDR"

xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"

xmlns:xsd="http://www.w3.org/2001/XMLSchema"

xmlns=http://schemas.xmlsoap.org/wsdl/> ...



<message name="AddressMessage">

<part name="address" element="addr:address" />

</message>...



<service name="AddressUpdateService">

<documentation>Update a customers mailing address</documentation>

<port name="AddressUpdate_Port" binding="tns:AddressUpdate_Binding">

<soap:address location="http://www.monson-haefel.org/jwsbook/BookPrice" />

</port>

</service> </definitions>



XML parsers and other tools can use XML namespaces

to process, sort, and search XML elements in a

document according to their QNames. This allows

reusable code modules to be invoked for specific

namespaces.

XML namespaces also allow for a great versioningsystem. If the Address Markup changes, we can assign

the new version its own namespace.



W3C XML Schema Language

XML Schema Basics

The XML specification includes the Document Type Definition

(DTD), which can be used to describe XML markuplanguages and to validate instances of them (XMLdocuments). While DTDs have proven very useful over theyears, they are also limited. To address limitations of DTDs,

the W3C (World Wide Web Consortium), which managesthe fundamental XML standards, created a new way todescribe markup languages called XML schema.




Why XML Schema Is Preferred to DTDs in Web Services?

<?xml version="1.0" encoding="UTF-8"?>

<!ELEMENT address (street+, city, state, zip)>

<!ELEMENT street (#PCDATA) >

<!ELEMENT city (#PCDATA) >

<!ELEMENT state (#PCDATA) ><!ELEMENT zip (#PCDATA) >

<!ATTLIST address category CDATA #REQUIRED >




DIFFERENCES DTD'S SCHEMAS

DATA CONSTRAINTS DTD's have minimal data constraints. Schemas allow more specific constraints

USER DEFINED TYPES

DTD's limit to a fixed set of content

models

DTDs don't support types like integer,decimal, Boolean, and enumeration

Schemas provide greater flexibility XML

schema is superior to DTD because it

defines a richer type system, which

includes simple primitives (integer,

double, boolean, among others).



W3C XML Schema Language<?xml version="1.0" encoding="UTF-8"?>

<schema xmlns="http://www.w3.org/2001/XMLSchema"

xmlns:mh="http://www.Monson-Haefel.com/jwsbook"

targetNamespace="http://www.Monson-Haefel.com/jwsbook">

<element name="address" type="mh:USAddress" />

<complexType name="USAddress">

<sequence>

<element name="name" type="string" />

<element name="street" type="string" />

<element name="city" type="string" />

<element name="state" type="string" />

<element name="zip" type="string" />

</sequence>

</complexType>

...

</schema>



The XML Schema Document

A schema describes the structure of an XML document

in terms of complex types and simple types. Complex types describe how elements are organized

and nested

. Simple types are the primitive data types contained

by elements and attributes.



The XML Schema Document<?xml version="1.0" encoding="UTF-8"?>

<schema xmlns="http://www.w3.org/2001/XMLSchema"

xmlns:mh="http://www.Monson-Haefel.com/jwsbook"

targetNamespace="http://www.Monson-Haefel.com/jwsbook">

<element name="address" type="mh:USAddress" />


<sequence>






</sequence>

</complexType> ...

</schema>



Simple Types

, a simple element type will not contain other

elements; it will contain only data. .The XML schema specification defines many standard

simple types.



XML Schema Built-in Simple Types Java Primitive Types

<?xml version="1.0" encoding="UTF-8"?>

<schema xmlns=http://www.w3.org/2001/XMLSchema

xmlns:mh=http://www.Monson-Haefel.com/jwsbook

targetNamespace="http://www.Monson-Haefel.com

/jwsbook">

...

<complexType name="PurchaseOrder">

<sequence><element name="accountName" type="string" />

<element name="accountNumber" type="integer´ >

<element name="total´ type="float" />



</sequence>

</complexType>

...

</schema>

package com.monsonhaefel.jwsbook;

public class PurchaseOrder

{

String accountName;

int accountNumber;

float total;

// more stuff follows}



XML Schema Built-in Simple Types

Simple Type Definition

string A sequence of characters conforming to UCS

normalizedString A string without carriage returns, line feeds, or tabs

token A string without spaces, line feeds, or tabs

NMTOKEN A token used in attributes

byte A non-decimal number between ±128 and 127

unsignedByte A non-decimal number between 0 and 255

base64Binary Base64-encoded binary data (RFC 2045)[a]

hexBinary Hex-encoded binary data[b]

integer A base-10-integer number of any size («)[c]

positiveInteger A base-10 integer greater then zero (1, 2, «)





negativeInteger A base-10 integer less then zero («, ±2, ±1)

int A base-10 integer between ±2,147,483,648 and 2,147,483,647 (±2 billion and 2

billion)

unsignedInt A base-10 integer between 0 and 4,294,967,295 (zero and 4 billion)

long A base-10 integer between ±9,223,372,036,854,775,808 and

9,223,372,036,854,775,807 (±9 quintillion and 9 quintillion)

unsignedLong A base-10 integer between 0 and 18,446,744,073,709,551,615 (zero and 18

quintillion)

short A base-10 integer between ±32,767 and 32,767

unsignedShort A base-10 integer between 0 and 65,535

decimal A decimal number of any precision and size

float A decimal number conforming to the IEEE single-precision 32-bit floating-point





boolean A boolean value of "true" or "false"

You can also use the values of "0" (false) or "1" (true); either convention is fine.

time A time in hours, minutes, seconds, and milliseconds formatted as hh:mm:ss.sss (e.g.,

1:20 PM is 13:20:00)

You may include the optional Coordinated Universal Time (UTC) designator (e.g.,

1:20 PM Eastern Standard Time (EST) is 13:20:00-05:00)[e]

date A Gregorian date in centuries, years, months, and days (e.g., December 31, 2004 is

2004-12-31)[e]

dateTime A Gregorian date measured in centuries, years, months, and days, with a time fieldset off by a T (e.g., 1:20 PM EST on December 31, 2004 would be 2004-12-

31T13:20:00-05:00)[e]

duration A span of time measured in years, months, days, and seconds (e.g., 1 year, 2 months,

3 days, 10 hours, and 30 minutes would be P1Y2M3DT10H30M)



Complex Types complex types define how elements that contain other elements are

organized.


<sequence>






</sequence>

</complexType>



Complex Types

Sequences of Elements :complexType declarations in

schemas will contain a sequence element that lists one

or more element definitions. The element definitions

tell you which elements are nested in the type, the

order in which they appear, and the kind of data

each element contains.



Mapping a Schema Complex Type to an XML Element

XML Schema: USAddress XML Document: address


<sequence>


<element name="street" type="string" /><element name="city" type="string" />



</sequence>

</complexType>

<address>


<

street>1516 2nd Ave<

/street><city>Seattle</city>

<state>WA</state>

<zip>90952</zip>

</address>

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