XML abbreviation stands for Extensible Markup Language,which describes a class of data objects called XML documents and partially describes the behavior of computer programs which process them.
It was developed by what is called a XML Working Group which was formed under the auspices of the WWW Consortium in 1996.
Some of the design goals for XML are:
- It shall be straightforwardly usable over the Internet.
- It shall support a wide variety of applications.
- It shall be compatible with SGML.
- It shall be easy to write programs which process XML documents.
- The XML design should be prepared quickly.
- XML documents shall be easy to create.
- Terseness in XML markup is of minimal importance.
This points helps us to understand better the XML 1.0., but we can’t forget that now 2.0 Web does already exist, and construct computer programs to process it.
By construction, XML documents are conforming SGML (Standard Generalized Markup Language ) documents.Each XML document has both a logical and a physical structure. Physically, the document is composed of units called entities. An entity may refer to other entities to cause their inclusion in the document. A document begins in a “root” or document entity. Logically, the document is composed of declarations, elements, comments, character references, and processing instructions, all of which are indicated in the document by explicit markup.
- Extensible Markup Language: http://www.w3.org/TR/1998/REC-xml-19980210#sec-intro
- The Free Encyclopedia: http://en.wikipedia.org/wiki/XML