HTML - Roggeweck

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Transcript HTML - Roggeweck 

Web Technologies
By Andreas Vetter and Yong Soo Deutschle
Table of Content
• HTML
• XHTML
• XML
HTML
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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 SGMLdefined 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
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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 (< font>... </font>)
• Comment tags: <!-- .... -->
• There are special tags who not need an
end tag, like <br>
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>
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
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What is XHTML
History
Main characteristics of XHTML
Syntax rules
Conclusion
What is XHTML
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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 HTMLJungle 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
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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 machinemachine 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
RATIONAL
DATA BASES
Semi
Structured Data
Non
Structured Data
XML
FLOW TEXT
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>
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?