Specification details of various XML technologies

XML specification means a syntax created by an existing international text-processing standard for use on the World Wide Web. The specifications related to the latest versions can be obtained from the site http://www.w3.org/TR/REC-xml

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XML NAMESPACES:

The specification on XML namespaces is a recommendation of the W3C.It acts as a reference material to the other related documents. This improvises the functionality and the interoperability of the Web. This site gives a summary on basic concepts of XMLnamespaces, declaring them, namespace scoping, namespace defaulting etc.,

They provide a simple and an elegant method for qualifying element and attribute names used in XML documents by associating them with the namespaces. A namespace is a collection of names, used in the XML documents as element types and attribute names.

The specifications on XML namespaces can be obtained in the site:

http://WWW.W3.org/TR/2004/REC-xml-names11-20040204

XML INFORMATION SET:

The XML Information set specification provides a set of definitions for use in other specifications that refers the information in an XML document. This document gives an idea on information systems, the document information item, element information items, attribute information items etc.,

It specifies the abstract set of definitions that can be used in a well-formed XML document. It is not necessary that an XML document should be valid to have information set though it must satisfy some namespace constraints, the structure can be in any language such as XSD, RELAX NG, or ASN.1.The XML Data and its information set are used by many applications. They have a widely different data models ranging from very simple trees to irregular structured graphs using a lot of nodes and vertices.

The specifications can be obtained in the site:

http://WWW.W3C.org/TR/2004/REC-xml-infoset-20040204

XML PATH LANGUAGE:

The XML Path Language specification document can be used asa reference material from other documents.W3C plays a very important role to draw attention to the specification and to improve its widespread deployment.This specification is due to the combined effort of the XSL Working group and the XML linking Group.It is a part of the W3C Style activity and the W3C XML activity.Xpath is a language that is used to find the address of different parts of an XML document, that is designed to be used by both an XSLT or an Xpointer.Xpath allows us to manipulate strings, numbers and Boolean. The primary construct in an Xpath is the expression. An expression is evaluated to yield an object. It has four basic types:

• node-set: It is an unordered collection of nodes without duplicates;
• Boolean: true or false;
• Number: It is a floating-point number;
• String: It is a sequence of Unicode characters

The evaluation of an expression occurs with respect to a context. The context consists of:

* A context Node
* A pair of non-zero positive integers
* A set of variable bindings.
* A function Library
* The Set of Namespace Declarations in scope for the expression

The specifications can be obtained in the site:
http://www.w3.org/TR/1999/REC-xpath-19991116

XSL TRANSFORMATIONS:

XSL Transformation specification document site gives an idea about the Style Sheet Structure, XSLT namespace, Style Sheet Element, Qualified names, Combining Style Sheets, Embedding Style sheets etc.,It is a language for transforming XML documents to other XML documents. XSLT is designed to be used as a part of XSL, which is a style sheet language for XML.XSL, also contains an XML vocabulary for specifying formatting. XSLT can also be used independently without using XSL.XSL is designed for transformations that are needed when XSLT is used as a part of XSL.

The specifications can be obtained in the site:
http://WWW.W3C.org/TR/1999/REC-xslt-19991116

XML SCHEMA:

The XML Schema specification document gives information regarding the basic concepts of The Purchase Order, The Purchase Order Schema, Complex type Definitions, Element &attrbute declarations, Building Content Models etc.,
XML schema specifies the XML schema definition language, which provides facilities for describing the structure and the contents of the XML documents. XML schema is an alternative to DTD.An XML schema can define the following:

• It can define the elements that can appear in a document
• It can define the attributes that can appear in a document.
• It can specify which elements are the child elements.
• It can define the order of the child elements.
• It can define the number of the child elements.

The specifications can be obtained in the site:
http://WWW.W3C.org/TR/2004/PER-xmlschema-0-20040318

XQUERY: AN XML QUERY LANGUAGE

The XQUERY specification document gives introduction to the formal Seamntics, XML Values, the Xpath/Xquery System, Processing model and main judgements, relationship with the other documents etc.,

It describes about a query language called Xquery to be applied across many types of XML data sources. Xquery provides flexible Query facilities to extract data from real and virtual documents, providing the interaction between the Web World and the Database World. All the XML files can be accessed, as databases. Xquery is a technology is developed under W3C that includes relational databases. The Queries are concise and are easily understood in a language. It is also possible to query a large volume of XML data including the databases and documents.
The specifications can be obtained in the site:
http://WWW.W3C.org/TR/2004/WD-xquery-semantics-20040220