XML Basics

XML, or Extensible Markup Language, is not new. In fact, it’s a subset of SGML, the Standardized General Markup Language, modified for use on the Web. SGML was originally developed by Goldfarb, Mosher, and Lorie at IBM in 1969, as a way to structure legal documents; it has evolved over time into an international standard for representing textual data in system-independent format. Since SGML is overly complex for the requirements of the Web, XML has evolved as a modified (read: simpler) version of SGML, adapted specifically for use on the Web.

While HTML is great for putting together Web pages, it doesn’t offer any way to describe the data contained within those pages. As a formatting language, it doesn’t offer any mechanism to define structures within the document, thereby limiting its usefulness. The fact that it understands a limited set of tags – and even that frequently depends on which browser you’re using – reduces its flexibility and makes it difficult to extend its usefulness to other applications.

XML was designed to avoid these disadvantages by creating a markup language which would be simple yet flexible, easy to use yet powerful enough to offer a variety of different applications. Briefly, the original design goals for XML were: XML should be simple and easy to use. XML should support a variety of different applications, by allowing users to develop their own markup.

XML documents should precisely follow certain formally-defined rules and principals. XML documents should be human-legible and reasonably clear.

Over the past year and a half, the XML universe has grown by leaps and bounds to include many new technologies, most with hard-to-remember acronyms. Here’s a quick list of the important ones, and how they fit into the larger picture:

XML Schema makes it possible to define the structure and format of “classes” of XML documents, providing more advanced features than those offered by the regular Document Type Definition (DTD).

XLink is a specification for linking XML data structures together, in much the same way as the hyperlinks available in HTML… although Xlink allows for far more sophisticated types of links, including simultaneous links to more than one resource.

XPointer is a specification for navigating the hierarchical tree structure if an XML document, and referencing elements, attributes and other data structures within the document.

XSL and XSLT: The Extensible Stylesheet Language (XSL) makes it possible to apply presentation rules to XML documents, and convert – or transform – them from one format to another.

XHTML: The next version of HTML, XHTML combines the precision of XML markup with the easy-to-understand tags of HTML to create a more powerful and flexible language.

XForms offers a way to improve the current crop of HTML-based forms by separating the function of the form from its appearance, thereby making it possible to easily adapt a form for display on a variety of devices and systems.

XML Query: The XML Query effort is focused on creating a specification that makes it possible to query one or more XML documents and generate usable result data (in much the same way as SQL is used to retrieve database records).

XML Encryption is a means of encrypting and decrypting XML documents, so as secure it against unauthorized usage.

The words to the text :

to evolve развивать(ся), развертывать(ся)

overly чрезмерно

to adopt принимать, усваивать

brief короткий, лаконичный

precise точный, аккуратный

ancillary подчиненный, вспомогательный

acronym сокращение

simultaneous одновременный

crop обилие, масса, совокупность

query вопрос, неточность