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Web Technologies

Web Technologies. By Andreas Vetter and Yong Soo Deutschle. Table of Content. HTML XHTML XML. HTML. What is HTML History What is it used for Tags & Structure Sample Conclusion. What is HTML. HTML ( H yper T ext M arkup L anguage)

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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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