ISYU TUNGKOL SA SEKSWLADIDA (ISSUE ABOUT SEXUALITY
Introduction to xml
1.
2. eXtensible Markup Language, is a
specification for creating custom
markup languages
W3C Recommendation
Primary purpose is to help computers to
share data
XML is meta-language. This means that
you use it for creating languages.
XML is an extensive concept.
3. Every XML-document is text-based
=> sharing data between different
computers!
=> sharing data in Internet!
=> platform independence!
4. Problems with Binary format
› Platform depence
› Firewalls
› Hard to debug
› Inspecting the file can be hard
Since XML is text-based, it does not have
the problems mentioned above.
What are the disadvantages in text
format?
5. XML is meta language, which you can use
to create your own markup languages.
There are several XML Markup Languages
made for different purposes
All the languages have common xml-rules
Languages: XHTML, OOXML, Open
Document, RSS, SVG, SOAP, SMIL, MathML...
List:
› http://en.wikipedia.org/wiki/List_of_XML_markup_languag
es
6. <?xml version="1.0"?>
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Minimal XHTML 1.0 Document</title>
</head>
<body>
<p>This is a minimal <a href="http://www.w3.org/TR/xhtml1/">XHTML 1.0</a>
document.</p>
</body>
</html>
12. There are two levels of correctness of an
XML document:
1. Well-formed. A well-formed document
conforms to all of XML's syntax rules.
2. Valid. A valid document additionally
conforms to some semantic rules.
Let's first look at the XML's syntax rules (1).
13. <?xml version="1.0" encoding="utf-8" standalone="yes"?>
<presentation>
<slide number="1">
<name>Introduction to XML</name>
<contents>XML is ...</contents>
</slide>
</presentation>
14. XML-declaration is optional in XML 1.0,
mandatory in 1.1.
› Recommendation: use it.
Version: 1.0 or 1.1
Encoding: character encoding, default utf-8
Standalone:
› is the xml-document linked to external markup
declaration
› yes: no external markup declarations
› no: can have external markup declaration (open
issue..)
› default: "no"
15. <?xml version="1.0" encoding="utf-8" standalone="no"?>
<presentation>
<slide>
<name>Introduction to XML</name>
<contents>XML is ...</contents>
</slide>
</presentation>
Same Declaration
<?xml version="1.0"?>
<presentation>
<slide>
<name>Introduction to XML</name>
<contents>XML is ...</contents>
</slide>
</presentation>
16. Element consists of start tag, optional content
and an end tag:
› <name>Introduction to XML</name>
Start tag
› <name>
Content
› Introduction to XML
End tag
› </name>
Start tag may have attribute
› <slide number="1">
17. Only one root - element
Every element contains starting tag and an ending
tag
Content is optional: Empty element
› <x></x> <!-- same as -->
› <x/>
Tag – names are case-sensitive:
› <X></x> <!-- Error -->
Elements must be ended with the end tag in
correct order:
› <p><i>problem here</p></i> <!– Error
18. XML elements can have attributes
in the start tag.
Attributes must be quoted:
› <person sex="female">
› <person sex='female'>
› <gangster name='George "Shotgun" Ziegler'>
› <gangster name="George
"Shotgun" Ziegler">
19. Names can contain letters, numbers,
and other characters
Names must not start with a number or
punctuation character
Names must not start with the letters xml
(or XML, or Xml, etc)
Names cannot contain spaces
20. XML document is well-formed if it follows
the syntax rules.
XML document must be well-formed!
› it's not an xml-document, if it does not follow
the rules..
24. XML document is valid if
› 1) It is well formed AND
› 2) It follows some semantic rules
XML document is usually linked to an
external file, that has semantic rules for the
document.
› The file can be dtd (.dtd) or schema (.xsd)
Semantic rules?
› Name of tags, order of elements
25. Because of HTML heritage, browsers try
to understand invalid XHTML-pages
This is not the case in other XML-
languages.
In general, if XML-document is
invalid, the processing of the document
is cancelled.
26. XML has strict rules for WF and Valid
If application tries to manipulate xml-
document it does not have to try to
understand the possible errors in the
document
This means that handling xml-files via
programming language is much easier
› If the document is correctly formed,
manipulate it
› If it isn't display error
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