Internet Revolution ? Another Markup Language or · PDF fileAnother Markup Language or...

SAP AG 1999 Knowledge Warehouse - XML (Dr. Wei-Guo Peng) / 1

XML:Another Markup Language or

Internet Revolution ?

Dr. Wei-Guo Peng

[email protected]

SAP AG


Table of Content

Part 1: XML for managers� What is XML?

� Why is XML so hot?

� XML applications and tools

Part 2: XML for programmers� XML and XSLT syntax

� SAX and DOM

� XML programming model


A Little History of Information Technology

OfficeAutomation

EnterpriseAutomation

Inter-EnterpriseAutomation


Part One

Part 1: XML for managers� What is XML?

� Why is XML so hot?

� XML applications and tools


XML: W3C Definition

The Extensible Markup Language (XML) is asubset of SGML that is completelydescribed in this document. Its goal is toenable generic SGML to be served,received, and processed on the Web in theway that is now possible with HTML. XMLhas been designed for ease ofimplementation and for interoperability withboth SGML and HTML.


XML: What others say (1)

� Utzschneider - Microsoft„It's not a question of whether or not you're going toneed XML -- you're going to choose to use XML in thesame way companies five years ago chose to use HTMLand HTTP. Companies weren't dragged kicking andscreaming to use browsers. They chose to usebrowsers.“

� Phip Costa - Giga Infomation Group"It's becoming pretty clear that XML is going to be awidely deployed technology,"

� Mark Driver - Gartner Group„XML is not a product or a platform. Neither is it thesecond coming of Java, nor a latter-day SQL. It is anenabling technology, like IP itself.“


XML: What others say (2)

� Frank Gillett - Forrester Research„XML has only just reached the point where it is startingto ramp up big.“

� Lamoureux:„XML is just too compelling to ignore. „

� Microsoft:„The key enabler for Microsoft's vision of integrated,programmable Web services is XML.“

� Doug Tidwell - IBM„A technical revolution comparable in scope to slicedbread and the wheel.“


Future SAP Application Programming

App. Server

App. Server

App. Server

MessageBroker SAP

App Server

Presentation Server

HTTP + XML

HTTP + XML

ApplicationBackbone/Fulfillment Engine

Browser Clients(form caching, data chunking)

HTTP + HTML + XML

� Presentation open forcustomer adaptation

� Application flow open forcustomer adaptation

Presentation server benefits:

InternetValue Network

Internet/Intranet

ExistingSAP clients


The Internet Revolutions

TCP/IPUniversal Connectivity

XMLUniversal Data

HTMLUniversal Rendering

HTTPUniversal Transport

The First Internet Revolution

Mrs. Mary McGoon 1401 Main Street Anytown, NC 34829



Markup


What is HTML

� HTML is a markup language

� Fixed tag semantics

� Industrial standard - in version 3.2, 4.0

� Netscape Navigator 4.0 / Internet Explorer 5.0

� DHTML� interactive

� browser independent


HTML Demo

Demo

What is XML

<address country=„us“><name>

<title>Mrs. </title><first-name>Mary</first-name><last-name>McGoon</last-name>

</name><street>1401 Main Street</street><city>Anytown</city><state>NC</state><zipcode>34829</zipcode>

</address>

Tag

MarkupContent

Attribute


XML Components

� Data / Document� XML

� Type Information (meta data)� DTD/Schema

� In-Memory Programming Model� DOM

� Style and Transformation� XSL (XSLT)


XML: Markups

� Character data (Unicode)

� Element

� Entity reference

� Comment

� Processing instruction

� Document type declararion

� CDATA section

XML documents contain:

DTD: Document Type Language

<!ELEMENT address (name, street, city, state,zipcode)*>

<!ELEMENT name (title, first-name, last-name)>

<!ELEMENT title (#PCDATA)><!ELEMENT first-name (#PCDATA)><!ELEMENT last-name (#PCDATA)><!ELEMENT street (#PCDATA)><!ELEMENT city (#PCDATA)><!ELEMENT state (#PCDATA)><!ELEMENT zipcode (#PCDATA)><!ATTLIST addresscountry CDATA #IMPLIED

>

<!ELEMENT>

<!ATTLIST>


DTD and Schema

•DTD•is included in XML 1.0•its own syntax•document-oriented data types

•Schema•not yet a standard•XML syntax•data-oriented data types•enables reuse•supports namespace

•Use DTD instead of Schema


XML: Well-formed vs. Valid Documents

� Well-formed� Valid syntax

� No mulitvalued attributes

� Non-empty tags must be properly nested

� Parameter entities must be declared before they are used� All entities except the following: amp, lt, gt, apos, andquot must be declared

� A binary entity is reference as entity

� no recursive entities are allowed

� Valid� Contains DTD

� Obeys the constraints defined in DTD

XSL - eXtensible Stylesheet Language

<?xml version='1.0'?>

<xsl:stylesheet xmlns:xsl="http://www.w3.org/TR/WD-xsl"><xsl:template match="/"><HTML>

<xsl:value-of select="address/name/title"/><xsl:value-of select="address/name/first-name"/><xsl:value-of select="address/name/last-name"/>

 <xsl:value-of select="address/street"/> <xsl:value-of select="address/city"/>,<xsl:value-of select="address/state"/><xsl:value-of select="/address/zipcode"/>

</HTML></xsl:template></xsl:stylesheet>


XSLT: XSL Transformation

� Translate one XML language to another� Mapping between industries

� XML -> HTML

� Filter XML� Fetch the needed data

� Generate new data

� Declarative� Simple


Why XML?


XML Demo

Demo


XML: Markups

� Character data (Unicode)

� Element

� Entity reference

� Comment

� Processing instruction

� Document type declararion

� CDATA section

XML documents contain:


Features of XML

� Simple

� Human readable - Text format

� Industrial standard - vendor indepenent

� User extensible

� Structed document / Structured data

� Semantic Web - Web automation

� Metadata


Separation of data from its representation (1)

� Same content, different user agent

XML html

wml

mp3

pdf

html


Separation of data from its representation (2)

� Model, content, and layout belong to different user roles

XMLDTD Stylesheet

Editing Authoring Designing


Platform and Application Independent

� Everything is text

� No special editor is needed

� Every applications can read or write their data in XML

XML


Valuable metadata

� Metadata is expressed with:� DTD / XMLSchema� Tag name� Attribute� Datatype

� Can be used to validate XML data


Extensibility

� Free definable tags

� Self defined structure – schema

� Newly added elements won´t break the old application


Self-describing and Portable

� Self-describing� text format

� tags tell the meaning

� DTD as documentation

� Portable� standard format

� parser is widely available


Maintainability

� Flexible� tag oriented not line oriented

� Backward compatible� new tags

� new attribute

� Program at a higher level� less to code

� standard parser and DOM

� Easy debugging� text format


Internationalization

� UNICODE� www.unicode.org

� UTF-8

� UTF-16

� User defined character set� GB

� BIG5


Basic XML Tools

� XML Editor� XMetal, Adept Editor, FrameMaker, Notepad, vi

� XML Parser / Generator (DOM / SAX)� MSXML, X4J, expat

� XSL Processor� MSXSL

� XML Browser� IE5.0


Related Standards

XSL

XLink

WML

XPath

DOM

MathML

SMIL XSchema

RDF

CDF


3-tier Architecture: Web Enabling


Application Areas (1)

XMLUniversal Data

XML-RFCSOAP

eBusiness

ConfigurationPersonalization

DocumentManagement

Publishing

ApplicationIntegration

BusinessPortal

Inter-Application

Data Exchange


Application Areas (2)

XMLStructured Data

DatabaseIntegration

StructureSearch

ObjectPersistency

TechnicalDocument


Is XML a silver bullet?

� Standard syntax != standard semantic� domain-specific XML: bizTalk, finXML, OASIS� transformation (XSLT)

� A lot of standards are confusing� Document oriented, not yet data oriented

� data type� constraints

� DTD is not standardized� SML (Simplified XML)

� No attributes, PI, DTD, non-char entity ref, no CDATA� Only UTF-8


Summary

� XML will not replace HTML at least not NOW

� XML is a language for data

� HTML is a language for rendering

� XSLT is the language for transformation


Part Two

Part 2: XML for programmers� XML and XSLT syntax

� SAX and DOM

� XML tools


XML: Interesting Links and Meetings

� www.xml.com - Anotated XML 1.0� www.oasis-open.org/cover� www.w3.org� msdn.microsoft.com/xml� xdev.datachannel.com

� comp.text.xml� microsoft.public.xml

� XML Europe� XML World� XML One


Two standards groups

� IETF - Internet Engineering Task Forcewww.ietf.org

� W3C - World Wide Web Consortiumwww.w3.org


XML Big Players

� MicrosoftMSXML, bizTalk, SQL server exports XML

� Ariba - OMR

� CommerceOne

� Vignette

� webMethods

� Abortext

� Adobe

� SoftQuad

� Chrystal

� Waltham


Document Type Definition (DTD)

� Specifies the content model� valid element names (tags)

� valid attribute names and values

� how elements can nest in each other(number/sequence)

� Used to validate a document

� Typically DTD is stored in a separated file

� As documentation

DTD Element Declarations

� Specifies tree-like structure

� Uses regular expressions to define valid content

� Example:� <!ELEMENT el EMPTY>

� <!ELEMENT el ANY>

� <!ELEMENT mail (subject, from, to?, text)* >

DTD Attribute List Declarations

� Defines allowed attribute names and values of an element

� No multivalued attributes

� Limited data type - all are strings

� Example:� <!ATTLIST el

id ID #IMPLIEDname CDATA #REQUIREDtype (str|int|bool|float) „str“

>

DTD Attribute Types

� CDATA - Any value

� ID - must be unique in the whole document

� IDREF - Reference to an element with a specific ID

� Example:� <!ATTLIST el

id ID #IMPLIEDname CDATA #REQUIREDtype (str|int|bool|float) „str“

>


XML: DOM (Document Object Model)

� Standard programmatic access of XML/HTML� Defined at the API level (interface instead of

implementation)� Programming language independent� Current version - level two� Navigation of tree like structure� Requires a lot of memory� Basic element is „Node“


XML: SAX - Simple API for XML

� Event-driven� define event handler (startElement(), endElement())

� register event handler in an XML parser

� Simple

� Less memory consumption

� No tree structure

� No navigation


Namespace

� Avoid name conflict

� Example


Which Stylesheet to use?

� W3C recommendation:Use CSS when you can, use XSL when you must.


Example: Wireless Application Protocol (1)

� WAP creates the mobile internet. Access interneteverywhere

� WAP is a standard support by Nokia, Ericsson,Motorola, Phone.com

� Build-in billing mechanism. Credit card not needed

� 3 times more cell phone users than internet users



� WML

� WMLScript

� WBMP

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