XML based standards

XML based standards

We have already discussed the advantages of the ―ML‖ in XML, but the ―X‖ presents advantages of its own. Extensibility, as applied to XML, is the ability for the language tobe used to define specific vocabularies and metadata. Rather than being fixed in describing a particular set of data, XML, in conjunction with its DTDs and schema, is able to define any number of documents that together form a language of their own.

Indeed, hundreds, if not thousands, of specific document vocabularies have been created based on XML to meet the different needs of healthcare, manufacturing, user interface design, petroleum refining, and even chess games. Text files and relational database schemas are rigid in that they are meant to represent the information contained within and nothing more. It would be a difficult proposition at best to add a new set of information to a text file or relational database management system (RDBMS). XML files, especially those created using an ―open content model,‖ can easily be extended by adding additional elements and attributes. Whole classes of documents can be defined simply by sending a document with a new DTD or schema. Sharing a DTD and schema within a user community results in a joint specification—if not a de facto or explicit standard.

XML BASED STANDARDS:

1) XPATH

XPath is a syntax for defining parts of an XML document. XPath uses path expressions to navigate in XML documents. XPath contains a library of standard functions. XPath is a major element in XSLT. XPath is a W3C Standard

2)      XSD

It defines elements that can appear in a document. defines attributes that can appear in a document. It defines which elements are child elements. defines the order of child elements. It defines the number of child elements. It defines whether an element is empty or can include text. It defines data types for elements and attributes. It defines default and fixed values for elements and attributes

3)      XSL

XSL describes how the XML document should be displayed! XSL consists of three parts:XSLT - a language for transforming XML documents, XPath - a language for navigating in XML documents, XSL-FO - a language for formatting XML documents

4)      XSLT

A common way to describe the transformation process is to say that XSLT transforms an XML source-tree into an XML result-tree.XSLT stands for XSL Transformations. XSLT is the most important part of XSL. XSLT transforms an XML document into another XML document. XSLT uses XPath to navigate in XML documents. XSLT is a W3C Recommendation.