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Web Technologies

This document explores the fundamental concepts of HTML, XHTML, and XML, key technologies in web development. HTML (HyperText Markup Language), developed in 1990, serves as the backbone of web content, while XHTML was introduced as a stricter, XML-based evolution of HTML. XML (Extensible Markup Language) offers a flexible approach for data representation. The document covers the history of these languages, their structure and usage, as well as advantages and disadvantages, providing insight into their significance in web applications.

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Web Technologies

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  1. Web Technologies By Andreas Vetter and Yong Soo Deutschle

  2. Table of Content • HTML • XHTML • XML

  3. HTML • What is HTML • History • What is it used for • Tags & Structure Sample • Conclusion

  4. What is HTML • HTML (HyperText Markup Language) • Language for publications in the World Wide Web, text format for HTTP • Basic language = English • Developed 1990 by Berners Lee; • based very strongly on SGML

  5. SGML: a Brief Introduction • Standardized General Markup Language • In 1986, ISO approved an international standard for descriptive markup • SGML is a metalanguage for defining markup languages • HTML is one example of an SGML-defined language

  6. History of HTML • HTML 2.0is the official standard, which defines those basic functions of HTML, which are meaningfully represented by all Web Browsern. • HTML 3.2is the most common used standard, which covers those HTML elements, which are supported to a large extent by nearly all Browser versions (starting from 1996/97). • HTML 4.0is a suggestion of the W3-Consortium, which is at least partly supported by newer Browser versions (starting from 1997/98). • The advancement of HTML starting from 1999/2000 will go into the direction from XHTML.

  7. What is it used for • Presenting information in LAN / WAN • Structure your text-based information • Hyperlinks to reach following texts • To Put images on your docs • Basic structure for all web applications, like Guestbooks, Online Stores, Forums, etc …

  8. HTML Standard Tags • TAG is, which stands within "<...>" • to an opening TAG belongs usually a closing TAG (< font>... </font>) • Comment tags: <!-- .... --> • There are special tags who not need an end tag, like <br>

  9. HTML Basic Structure <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>Title of the page</title> </head> <body> <h1><i>HTML</i> - the language of the web</h1> </body> </html>

  10. Conclusion • Advantage: HTML is easy to learn • Problems: • Almost nobody really cares about the standards of w3c, because the „Microsoft Internet Explorer“ (Leading Browser) is very obliging • As a result the parsers of the non-microsoft browsers can have significant problems in displaying pages correctly

  11. XHTML • What is XHTML • History • Main characteristics of XHTML • Syntax rules • Conclusion

  12. What is XHTML • EXtensible HyperText Markup Language • Supposed to replace HTML • nearly identically to HTML 4.01 • stricter and "more cleanly" version of HTML • HTML 4.01 on XML-Base

  13. History • Introduced in 26 January 2000 by W3C as the new official standard • Reason: Problems because of "bad" and "unsuitable" HTML => for search "more cleanly" and "more uniformly" programming

  14. Main characteristics of XHTML • correct nesting of the tags • XHTML documents must keep a certain form • permit no capital letters for the tags • All elements must be closed: END tag necessarily

  15. Important syntax rules • Attribute names must be written in small letters • Attributes must stand in " " • No attributes shortening • The ID attribute replaces the name attribute • The XHTML DTD defines obligatory elements.

  16. Conclusion • XHTML is supposed to make the HTML-Jungle clean, to make the Web-Pages suitable for all browser types. • Disadvantages: • Web developers have to obey the rules • Errors will not be tolerated => More expenditure of time

  17. XML • What is XML • XML – Motivation • XML – Classification • Sample • Conclution

  18. What is XML • XML (EXtensible Markup Language) • Guidance for writing of „Document Type Definitions“  DTD‘s • XML is more general and uniform than HTML, and simpler than SGML • SGML - (arcane features) + (new acronym) = XML!

  19. XML - Motivation • For closing gaps between machine-machine communication ... • ... applicable in the WWW • Easy to create • For humans and machines readable • To cover as much as possible areas of application

  20. XML - Classification Structured Data Semi Structured Data Non Structured Data FLOW TEXT XML RATIONAL DATA BASES

  21. Sample Code <?xml version=„1.0“ encoding=„ISO-8859-1“ ?> <book isbn=„3423085169“> <titel>Sofies Welt</titel> <autor> <name>Gaarder</name> <firstname>Jostein</firstname> </autor> <publisher>DTV</ publisher> <year>1993</year> </book>

  22. End - Conclusion • HTML • Markup language for the Web • Version and compatibility problems • XHTML • Tryes to solve this problems • XML • machine-machine communication

  23. Thanks for your attention! Questions?

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