What is XML?
Knowledge about extensible markup language(XML).
What is xml
- Xml (eXtensible Markup Language) is a mark up language.
- XML is designed to store and transport data.
- Xml was released in late 90’s. it was created to provide an easy to use and store self describing data.
- XML became a W3C Recommendation on February 10, 1998.
- XML is not a replacement for HTML.
- XML is designed to be self-descriptive.
- XML is designed to carry data, not to display data.
- XML tags are not predefined. You must define your own tags.
- XML is platform independent and language independent.
Note: Self-describing data is the data that describes both its content and structure.
What is mark-up language
A mark up language is a modern system for highlight or underline a document.
Students often underline or highlight a passage to revise easily, same in the sense of modern mark up language highlighting or underlining is replaced by tags.
Platform Independent and Language Independent: The main benefit of xml is that you can use it to take data from a program like Microsoft SQL, convert it into XML then share that XML with other programs and platforms. You can communicate between two platforms which are generally very difficult.
The main thing which makes XML truly powerful is its international acceptance. Many corporation use XML interfaces for databases, programming, office application mobile phones and more. It is due to its platform independent feature.
Features and Advantages of XML
XML is widely used in the era of web development. It is also used to simplify data storage and data sharing.
The main features or advantages of XML are given below.
1) XML separates data from HTML
If you need to display dynamic data in your HTML document, it will take a lot of work to edit the HTML each time the data changes.
With XML, data can be stored in separate XML files. This way you can focus on using HTML/CSS for display and layout, and be sure that changes in the underlying data will not require any changes to the HTML.
2) XML simplifies data sharing
In the real world, computer systems and databases contain data in incompatible formats.
XML data is stored in plain text format. This provides a software- and hardware-independent way of storing data.
This makes it much easier to create data that can be shared by different applications.
3) XML simplifies data transport
One of the most time-consuming challenges for developers is to exchange data between incompatible systems over the Internet.
Exchanging data as XML greatly reduces this complexity, since the data can be read by different incompatible applications.
4) XML simplifies Platform change
Upgrading to new systems (hardware or software platforms), is always time consuming. Large amounts of data must be converted and incompatible data is often lost.
XML data is stored in text format. This makes it easier to expand or upgrade to new operating systems, new applications, or new browsers, without losing data.
5) XML increases data availability
Different applications can access your data, not only in HTML pages, but also from XML data sources.
With XML, your data can be available to all kinds of “reading machines” (Handheld computers, voice machines, news feeds, etc), and make it more available for blind people, or people with other disabilities.
6) XML can be used to create new internet languages
A lot of new Internet languages are created with XML.
Here are some examples:
- WSDL for describing available web services
- WAP and WML as markup languages for handheld devices
- RSS languages for news feeds
- RDF and OWL for describing resources and ontology
- SMIL for describing multimedia for the web
XML documents create a hierarchical structure looks like a tree so it is known as XML Tree that starts at “the root” and branches to “the leaves”.
Example of XML Document
- <?xml version=”1.0″ encoding=”ISO-8859-1″?>
- <body>Don’t forget me this weekend!</body>
The first line is the XML declaration. It defines the XML version (1.0) and the encoding used (ISO-8859-1 = Latin-1/West European character set).
- <body>Don’t forget me this weekend!</body>
XML documents must contain a root element. This element is “the parent” of all other elements.
The elements in an XML document form a document tree. The tree starts at the root and branches to the lowest level of the tree.
The terms parent, child, and sibling are used to describe the relationships between elements. Parent elements have children. Children on the same level are called siblings (brothers or sisters).
All elements can have text content and attributes (just like in HTML).
Another Example of XML: Books
- <book category=”COOKING”>
- <title lang=”en”>Everyday Italian</title>
- <author>Giada De Laurentiis</author>
- <book category=”CHILDREN”>
- <title lang=”en”>Harry Potter</title>
- <author>J K. Rowling</author>
- <book category=”WEB”>
- <title lang=”en”>Learning XML</title>
- <author>Erik T. Ray</author>
The root element in the example is <bookstore>. All elements in the document are contained within <bookstore>.
The <book> element has 4 children: <title>,< author>, <year> and <price>.
Another Example of XML: Emails
- <?xml version=”1.0″ encoding=”UTF-8″?>
- <body>Hello brother, how are you!</body>
- <heading>Birth day wish</heading>
- <body>Happy birth day Tom!</body>
- <heading>Morning walk</heading>
- <body>Please start morning walk to stay fit!</body>
- <heading>Health Tips</heading>
- <body>Smoking is injurious to health!</body>