XML??? WHAT IS IT?? LET'S LEARN MORE!

   HAVE YOU EVER HEARD ABOUT XML???

 No?? What is it??

Sounds Weird??

    Now, just imagine it. What can you see in  your imagination? Actually guys,       knowledge can be interesting if we imagine it in a funny     way. Okay, have you done?Let me introduce you to Mr.XML. :)         

                 

 *~ Extensible Markup Language (XML) ~*          

• produced by the World Wide Web Consortium (W3C).
• a markup language that defines a set of rules for encoding documents in a           format that is both human-readable and machine-readable.
• It is defined in the XML 1.0 Specification.
• much like HTML.
• Tags are not predefined.
• DTD or an XML schema ( this schema is designed to self-descriptive ) to describe the data.

*~ Design Goals ~*

  simplicity, generality, and usability over the Internet.

• a textual data format with strong support via Unicode for the languages of the world. 

• Although the design of XML focuses on documents, it is widely used for the representation of arbitrary data structures, for example in web services.

*~ Key Terminology ~*

(Unicode) character

By definition, an XML document is a string of characters. Almost every legal Unicode character may appear in an XML document.

Processor and application

The processor analyzes the markup and passes structured information to an application. The specification places requirements on what an XML processor must do and not do, but the application is outside its scope. The processor (as the specification calls it) is often referred to colloquially as an XML parser.

Markup and content

The characters making up an XML document are divided into markup and content, which may be distinguished by the application of simple syntactic rules. Generally, strings that constitute markup either begin with the character < and end with a >, or they begin with the character & and end with a ;. Strings of characters that are not markup are content. However, in a CDATA section, the delimiters <![CDATA[ and ]]> are classified as markup, while the text between them is classified as content. In addition, whitespace before and after the outermost element is classified as markup.

Tag

A markup construct that begins with < and ends with >. Tags come in three flavors:

• start-tags; for example: <section>
• end-tags; for example: </section>
• empty-element tags; for example: <line-break />

Element

A logical document component which either begins with a start-tag and ends with a matching end-tag or consists only of an empty-element tag. The characters between the start- and end-tags, if any, are the element's content, and may contain markup, including other elements, which are called child elements. An example of an element is <Greeting>Hello, world.</Greeting> (seehello world). Another is <line-break />.

Attribute

A markup construct consisting of a name/value pair that exists within a start-tag or empty-element tag. In the example (below) the element img has two attributes, src and alt:

<img src="madonna.jpg" alt='Foligno Madonna, by Raphael'/>

Another example would be

<step number="3">Connect A to B.</step>

where the name of the attribute is "number" and the value is "3".

An XML attribute can only have a single value and each attribute can appear at most once on each element. In the common situation where a list of multiple values is desired, this must be done by encoding the list into a well-formed XML attribute^{[note 1]} with some format beyond what XML defines itself. Usually this is either a comma or semi-colon delimited list or, if the individual values are known not to contain spaces,^{[note 2]} a space-delimited list can be used.

<div class="inner greeting-box" >Hello!</div>

where the attribute "class" has both the value "inner greeting-box", indicating the CSS class names "inner" and "greeting-box".

XML declaration

XML documents may begin by declaring some information about themselves, as in the following example:

<?xml version="1.0" encoding="UTF-8"?>

want to know further about XML?? just click here : http://en.wikipedia.org/wiki/XML

*~The Difference Between XML and HTML~*

*~ XML ~*			*~ HTML ~*
I) XML is not a replacement for HTML.			*) HTML was designed to display data, with focus on how data looks.
ii) XML was designed to transport and store data, with focus on what data is.			**) HTML is about displaying information.
iii) while XML is about carrying information.