The XML Family
- The Document Object Model (DOM) is an application programmer interface (API) for
XML and HTML documents. It defines the way data in a document are structured,
accessed, and manipulated.This consists of five parts: Core,Views, Events, Style, and
Traversal and Range.These terms are more or less self-explanatory, but a further
explication can be found at http://xml.coverpages.org/dom.html.
- XQuery 1.0 and the XPath 2.0 Data Model are intended to define the information
contained in the input to an XSLT or XQuery processor.
Each of these four models describes an XML document as a tree structure, but there
are certain differences between them that we will not discuss here, the links in footnotes
point to sources of further information.
Outlines of the remaining three categories of XML technologies now follow.
XML Accessories are languages intended to extend the capabilities defined in the
XML specification. Examples of such accessories are XML Schema, which extends the
definition capability of XML Document Type Definitions (DTDs), and XML Names which
extends the naming mechanism to allow a single XML document to include element
and attribute names that are defined for and used by multiple software modules.These
concepts are becoming increasingly important and are discussed in more depth below.
XML Transformers (or Transducers) are languages intended for transforming input
XML data into a particular output form. Examples of this branch of the XML family are
Cascading Stylesheets (CSS) and the Extensible Stylesheet Language (XSL), both of which
produce an external presentation from XML data, and XSLT which transforms XML
documents into other formats, including XML.Transformer languages are associated with
some kind of processing model that defines how the output is derived from the input.
XML Applications define constraints for a class of XML data for a particular application
area, often by means of a DTD. Examples of XML applications are MathML (mathematical
data), XML-Signature (digital signatures), and SMIL (the Synchronized Multimedia Inte-
gration Language). XML accessories and transformers are often XML-based languages in
their own right, and thus they are also XML applications. Some dedicated XML formats
require a special type of player to access the con-
tent: SMIL files, for example, can be played using
one of around a dozen different applications, the
best known of which are Real Networks' RealOne,
GriNS, and the open-source X-Smiles.
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