Fundamental XML for Developers

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This session: Assumes you know nothing about XML or XML based technologies. Provides a basic introduction to XML based technologies. Demonstrates some of the basics of working with the DOM, XSLT, Schema, WSDL, and SOAP.

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Nội dung Text: Fundamental XML for Developers

Fundamental XML for Developers Dr. Timothy M. Chester Texas A&M University
Timothy M. Chester is. . . • Senior IT Manager, Texas A&M University – Application Development, Systems Integration, Developer Tools & Training • Lecturer, Texas A&M College of Business – Courses on Business Programming Fundamentals (VB.NET, C#), XML & Advanced Web Development. • Author – Visual Studio Magazine, Dr. Dobbs Journal, IT Professional • Consultant – President & Principal, eInternet Studios • Contact Information – E-mail: tim-chester@tamu.edu – Web: http://tim-chester.tamu.edu
Texas A&M University
You Are. . . • Software Developers – New to XML, Object Oriented Development – Require ‘basics’ of XML course • IT Managers – Need familiarity with XML basics and terminology – Interested in how XML can affect both software development and legacy system integration
This session . . . • Assumes you know nothing about XML or XML based technologies • Provides a basic introduction to XML based technologies • Demonstrates some of the basics of working with the DOM, XSLT, Schema, WSDL, and SOAP.
Agenda  XML • Document Object Model (DOM) • XPATH • XSLT • Schema • WSDL • SOAP • Questions
Underlying Technologies XML Is the Glue XML HTML y I P h no log TCP/ Tec Connecting Connectivity Presentation Inn Applications FTP, ov E -mail a ti , Gop on her Web P ages Connect Web Serv the Web Browse ices the Web Program the Web
Evolution of Web HTML, XML HTML HTML HTML, XML Generation 1 Generation 2 Generation 3 Static HTML Web Applications Web Services
Web Services Overview Application Model Partner Web Service Other Web Services Partner Web Service Internet + XML End Users YourCompany.com Application Business Logic Tier Data Access and Storage Tier Other Applications
Introducing XML • XML stands for Extensible Markup Language. A markup language specifies the structure and content of a document. • Because it is extensible, XML can be used to create a wide variety of document types.
Introducing XML • XML is a subset of a the Standard Generalized Markup Language (SGML) which was introduced in the 1980s. SGML is very complex and can be costly. • These reasons led to the creation of Hypertext Markup Language (HTML), a more easily used markup language. XML can be seen as sitting between SGML and HTML – easier to learn than SGML, but more robust than HTML.
The Limits of HTML • HTML was designed for formatting text on a Web page. It was not designed for dealing with the content of a Web page. Additional features have been added to HTML, but they do not solve data description or cataloging issues in an HTML document. • Because HTML is not extensible, it cannot be modified to meet specific needs. Browser developers have added features making HTML more robust, but this has resulted in a confusing mix of different HTML standards.
Introducing XML • HTML cannot be applied consistently. Different browsers require different standards making the final document appear differently on one browser compared with another.
Introduction to XML Markup • XML document (intro.xml) – Marks up message as XML – Commonly stored in text files • Extension .xml
Document begins with declaration 1 2 that specifies XML version 1.0 3 4 5 6 7 Welcome to XML! Element message is 8 child element of root element myMessage Line numbers are not part of XML document. We include them for clarity.
Introduction to XML Markup (cont.) • XML documents – Must contain exactly one root element • Attempting to create more than one root element is erroneous – Elements must be nested properly • Incorrect: hello • Correct: hello – Must be well-formed
XML Parsers • An XML processor (also called XML parser) evaluates the document to make sure it conforms to all XML specifications for structure and syntax. • XML parsers are strict. It is this rigidity built into XML that ensures XML code accepted by the parser will work the same everywhere.
XML Parsers • Microsoft’s parser is called MSXML and is built directly in IE versions 5.0 and above. • Netscape developed its own parser, called Mozilla, which is built into version 6.0 and above.
Parsers and Well-formed XML Documents (cont.) • XML parsers support – Document Object Model (DOM) • Builds tree structure containing document data in memory – Simple API for XML (SAX) • Generates events when tags, comments, etc. are encountered – (Events are notifications to the application)
Parsing an XML Document with MSXML • XML document – Contains data – Does not contain formatting information – Load XML document into Internet Explorer 5.0 • Document is parsed by msxml. • Places plus (+) or minus (-) signs next to container elements – Plus sign indicates that all child elements are hidden – Clicking plus sign expands container element » Displays children – Minus sign indicates that all child elements are visible – Clicking minus sign collapses container element » Hides children • Error generated, if document is not well formed