XML: An Introduction
What is XML?
"XML is a cross-platform, software and hardware independent tool for transmitting information"
XML is a W3C Recommendations. It stands for Extensible Markup Language . It is a markup language much like HTML used to describe data. In XML, tags are not predefined. A user defines his own tags and XML document structure like Document Type Definition (DTD) , XML Schema to describe the data. Hence it is self-descriptive too.There is Nothing Special About XML It is just plain text with the addition of some XML tags enclosed in angle brackets. In a simple text editor, the XML document is easily visible .
Why Is XML So Important?
There are number of reasons that contributes to the XML's increasing acceptance , few of them are:
In XML it is easy to create and edit files with anything from a standard text editor to a visual development environment. XML also provides scalability for anything from small configuration files to a company-wide data repository.
The markup tags in XML documents identifiy the information and break up the data into parts for example.. a search program can look for messages sent to particular people from the rest of the message. Different parts of the information are identified and further they can be used in different ways by different applications.
When display matters, the stylesheet standard, XSL
(an advance feature of XML), lets you dictate over the convectional
designs ( like using HTML) to portray the data.
- a plain text file
- an XHTML file
- a WML (Wireless
Markup Language) document suitable for display on a PDA
- an Adobe PDF
document suitable for hard copy
- a VML (Voice Markup
Language) dialog for a voicemail information system
- an SVG (Scalable Vector Graphic) document that draws pictures of thermometers and water containers
Apart from being valid , restrictions are imposed on a xml file to abide by a DTD or a Schema to make it well-formed .Otherwise, the XML parser won't be able to read the data. XML is a vendor-neutral standard, so a user can choose among several XML parsers to process XML data.
XML documents get benefitted from their hierarchical structure. Hierarchical document structures are, faster to access. They are also easier to rearrange, because each piece is delimited. This makes xml files easy to modify and maintain.
XML documents can be composed of separate entities. XML entities can be included "in line" in a XML document. And this included sections look like a normal part of the document .A user can single-source a section so that an edit to it is reflected everywhere the section is used, and yet a document composed looks like a one-piece document.
How Can You Use XML?
Few Applications of XML
Although there are countless applications that use XML, here are a few examples of the applications that are making use of this technology.
Refined search results - With XML-specific tags, search engines can give users more refined search results. A search engine seeks the term in the tags, rather than the entire document, giving the user more precise results.
EDI Transactions - XML has made electronic data interchange (EDI) transactions accessible to a broader set of users. XML allows data to be exchanged, regardless of the computing systems or accounting applications being used.
Cell Phones - XML data is sent to some cell phones, which is then formatted by the specification of the cell phone software designer to display text, images and even play sounds! File Converters - Many applications have been written to convert existing documents into the XML standard. An example is a PDF to XML converter.
VoiceXML - Converts XML documents into an audio format so that a user can listen to an XML document.
and many more........