XML is a text based markup language that enables you to store data in a structured format. by using meaningful tags. The term 'extensible' implies that you can extend your ability to describe a document by defining meaningful tags for your applications. XML is a cross platform, hardware and software independent markup language. It enables computers to transfer structured data between markup languages. It enables computers to transfer structured data between heterogeneous systems. It enables common data interchange format in a number of applications. In the example of the B2B e-Commerce model, XML can be used to exchange data between the trading partners, thus eliminating the problem faced by EDI.
Web Architecture Using XML
In traditional web architecture, a client send a request to the server in a predefined format and receives the appropriate response. The advantage of using XML in runtime. This is possibly because the data stored in an XML document does not assume its intended use. Different applications can extract data according to their customized needs. Since XML is used to exchange data between various web applications, the coupling between the server applications and the client applications is relatively loose.
XML can encode non-relational data, as well as relational data structure. This enables the server applications to extract data from any data source, and helps the programmers to quickly build applications for the manipulations of that data.
The Following figure depicts the XML web applications.
Difference Between SGML, HTML and XML
In addition to XML, Mark-up language such as Standard Generalized mark-up Language (SGML) and Hypertext Mark-up Language (HTML) are also available.
SGML was released in 1980. It allows documents to describe their grammar by specifying the tag set used in the document and the structural relationship that these tags represent. This makes it possible to define individual formats for documents, handle large and complex documents and manage large information repositories. However, SGML is complex and difficult for developers to master.
HTML was created by Tim Berner-Lee in 1989 as a simple and effectively way of generating clear and readable documents. HTML enables you to crate documents and web pages that can be read by all web browsers. It uses a set of tags in Conformance with the SGML specification.
The World Wide Web Consortium (W3C) developed XML to enable the expansion of web technologies into the ne domains of documents processing and data interchange XML is a subset of SGML. It is designed to ease data exchange over the Internet.
Though HTML and XML are mark-up language they have different purposes, HTML is used for data presentation, whereas XML is used for data description and definition.