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 (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
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
History of HTML HTML 2.0 is the official standard, which defines those basic functions of HTML, which are meaningfully represented by all Web Browsern. HTML 3.2 is 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 4.0 is 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.
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 …
HTML Standard Tags TAG is, which stands within " " to an opening TAG belongs usually a closing TAG (... ) Comment tags: There are special tags who not need an end tag, like
HTML Basic Structure <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" " Title of the page HTML - the language of the web
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
XHTML What is XHTML History Main characteristics of XHTML Syntax rules Conclusion
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
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
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
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.
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
XML What is XML XML – Motivation XML – Classification Sample Conclution
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!
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
XML - Classification Structured Data Semi Structured Data Non Structured Data RATIONAL DATA BASES XML FLOW TEXT
Sample Code Sofies Welt Gaarder Jostein DTV 1993
End - Conclusion HTML –Markup language for the Web –Version and compatibility problems XHTML –Tryes to solve this problems XML –machine-machine communication
Thanks for your attention! Questions?