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XML – Extensible Markup Language. Sivakumar Kuttuva & Janus z Zalewski. What is XML?. Extensible Markup Language (XML) is a universal standard for electronic data exchange

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Xml extensible markup language

XML – Extensible Markup Language

Sivakumar Kuttuva

& Janusz Zalewski


What is xml
What is XML?

Extensible Markup Language (XML) is a universal standard for electronic data exchange

Provides a method of creating and using tags to identify the structure and contents of a document ignoring the formatting


How xml look like
How XML look like

<?xml version="1.0"?><Course> //Root Tag <Name>Java Programming</Name> //Element Course Name  <Department>EECS</Department> //Element Dept

  <Teacher>    <Name>Paul</Name>  </Teacher>  <Student>    <Name>Ron</Name>  </Student>  <Student>    <Name>Uma</Name>  </Student>  <Student>    <Name>Lindsay</Name>  </Student></Course>


Why xml came into existence 1
Why XML came into existence?(1)

  • Make it easier to provide metadata -- data about information

      <Department>EECS</Department>  <Teacher>    <Name>Paul Thompson</Name>  </Teacher>Here Name,Department are Metadata

  • Large-scale electronic publishing requires dynamic documents without changing document formats.

  • Internationalized media-independent electronic publishing.


Why xml came into existence 2
Why XML came into existence? (2)

  • Allow industries to define platform-independent protocols for the exchange of data, especially the data of electronic commerce.

  • Make it easy for people to process data using inexpensive software.


Two types of syntax standards
Two Types of Syntax Standards

  • XML documents must meet one of two syntax standards:

    • Well-formed (the basic standard) Document must meet minimum,

      standard criteria.

    • Valid

      Document must be well-formed and

      adhere to a DTD (Document Type Definition).


Well formed xml
Well-Formed XML

  • Well-formed criteria include:

    • All elements have a start and end tag with matching capitalization.

      • <B></B>

    • Proper element nesting.

      • <B><I></I></B>

      • not <B><I></B></I>

    • Attribute values are in single or double quotes.

      • <book call_no=" 3456-34567890-3456 ">

    • Empty elements need an end or closed start tag.

      • <IMG></IMG> or <IMG />


Why well formed matters
Why Well-Formed Matters

  • Guarantees the document’s syntax before sending it to an application.

  • A clean syntax guarantee which means less ambiguity which results in faster processing.

  • A well-formed violation is a fatal error.


Valid xml
Valid XML

  • To be valid, a document must be well-formed and adhere to a DTD.

  • A DTD Example is shown below

    • <!ELEMENT BOOKCATALOG (BOOK)+>

    • <!ELEMENT BOOK (TITLE, AUTHOR+, PUBLISHER?,PRICE?>

    • <!ATTLIST BOOK ISBN CDATA #REQUIRED>

    • <!ATTLIST BOOK BOOKTYPE (Fiction|SciFi|Fantasy) #IMPLIED>

    • <!ELEMENT TITLE (#PCDATA)>

    • <!ELEMENT AUTHOR (LASTNAME)>

    • <!ELEMENT LASTNAME (#PCDATA)>

    • <!ELEMENT PUBLISHER (#PCDATA)>

    • <!ELEMENT PRICE (#PCDATA)>


Valid xml1
Valid XML

  • DTD - Document Type Definition specifies:

    • Elements in the document.

      • Author, Publisher

    • Their attributes.

      • For Book Author, Publisher, Price are attributes

    • Whether they are mandatory or optional

  • A DTD effectively specifies the document’s grammatical rules.


A sample entry in the xml file adhering to the given dtd
A sample entry in the XML file adhering to the given DTD

  • <BOOKCATALOG>

  • <BOOK>

  • <ISBN>3456-34567890-3456</ISBN>

  • <TITLE>C++ Primer</TITLE>

  • <AUTHOR_LASTNAME>Tendulkar</AUTHOR_LASTNAME>

  • <PUBLISHER>McGraw Hill</PUBLISHER>

  • <PRICE>41.99</PRICE></BOOK>

  • </BOOKCATALOG>


Why use dtd
Why use DTD

  • Well-formed means the document meets a minimum standard set of rules.

  • A DTD helps to define user defined rules and languages provided the XML content adheres to the syntax standards likeWML, MAML, etc.


The components line 1
The Components – Line 1

  • <!ELEMENT Bookcatalog (Book+)>

  • Bookcatalog is the root element.

  • Bookcatalog can have one or more (indicated by the +) Book elements.


The components line 2
The Components – Line 2

  • <!ELEMENT Book (Title, Author, Publisher, Price)>

  • Each Book element can contain:

  • A title, author, publisher, price


The components line 4
The Components – Line 4

  • <!ATTLIST Book BookType (Fiction | SciFi | Nonfiction) Fiction.

  • Each Book element has a attribute BookType Three options (indicated by |) Fiction, SciFi and Non-Fiction with Fiction as default.


The components lines 5 9
The Components – Lines 5-9

  • The Remaining Elements Title through Price are #PCDATA

    • Parseable character data that the processor will check for entities and markup characters

    • Any <,>, or & in data specified as PCDATA must be represented by &lt; or &gt; or &amp;.


Schemas
Schemas

  • The next step beyond DTDs

  • Come from the database world

  • More powerful and extensible than DTDs, which come from the SGML world

  • Schemas are XML documents, so they:

    • Are extensible

    • Use XML syntax unlike DTDs

    • Support data types like dates, times, currencies, important in eCommerce


Dtds vs schemas
DTDs vs Schemas

  • Why use schemas?

    • More powerful than DTDs

    • Better suited for eCommerce.

  • Why use DTDs?

    • Wider tool support.

    • More examples available for use and reference.

      • HTML,XHTML,CALS,etc.

    • Greater depth of experience in the industry

    • Wider pool of developers


Css and xml
CSS and XML

  • CSS was designed for HTML but works fine under XML as well.

  • Rather than create an XSL style sheet, you can create a simpler CSS and attach it to a XML document via a command like:

    • {?xml-stylesheet href=“mycss.css” type=“text/css”?}


Css and xsl
CSS and XSL

  • XML uses custom tags that a browser does not know how to display

  • So XML documents may display like this

    • <BOOKCATALOG>

    • <BOOK>

    • <ISBN>3456-34567890-3456</ISBN>

    • <TITLE>C++ Primer</TITLE>

    • <AUTHOR_LASTNAME>Tendulkar</AUTHOR_LASTNAME>

    • <PUBLISHER>McGraw Hill</PUBLISHER>

    • <PRICE>41.99</PRICE></BOOK>

    • </BOOKCATALOG>

  • Legibility requires applying styles:

  • – CSS

  • – XSL


Xsl extensible style language
XSL (Extensible Style Language)

  • XSL comes from DSSSL (Document Style Semantics and Specification Language), the SGML style language, derived from LISP.


Benefits of xsl
Benefits of XSL

  • An XSL style sheet is well-formed XML.

  • Supports a style sheet DTD for validation.

  • Far greater processing ability than CSS.

  • XSL Transformations (XSLT) take part ofan XML document and transform it, such as XML to HTML.

    – This is why XML appears to be the route to

    single-sourcing.


Advanced features of xml
Advanced Features of XML

  • Xlink

  • Xpointer

  • Parsing XML with DOM

    (Document Object Model)

  • XPath


Xml applications
XML Applications

  • Applications that require the Web client to mediate between two or more heterogeneous databases like information tracking system for a home health care agency.

  • Applications that attempt to distribute a significant proportion of the processing load from the Web server to the Web client like technicaldata delivery system for a wide range of products.

  • Applications that require the Web client to present different views of the same data to different users.

  • Applications in which intelligent Web agents attempt to tailor information discovery to the needs of individual users.


Future demands of xml
Future Demands of XML

  • Intelligent Web agents would have demand for structured data

  • User preferences must be represented in a standard way to mass media providers.


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