eXtensible Markup Language Became a W3C recommendation in 1998 Subset of SGML (Standard Generalized Markup Language) Describes a class of data objects called XML documents Metalanguage (language for describing other languages) Tags are not predefined, designed to be self-prescriptive“XML is a software- and hardware-dependent tool forcarrying information.”4
The goal of XML: Why?To enable generic SGML to be Browsers never allowedserved, received, and SGMLprocessed on the Web in away that is not possible with HTML is easy to corrupt or breakHTML. XML has been designedto operate with both SGML Widespreadand HTML. Held back development XML fixes that by creating compulsory rules
The Basics XML documents consist entirely of characters from Unicode (not all Unicode characters are included). Characters that make up XML are divided into markup and content. Unicode character sets are encoded into bytes for storage or transmission. The processor analyses the markup and passes structured information to an application.
XML Document Begins with XML declaration and document type declaration Followed by Document Instance, containing root element (start/end tags) and elements enclosing the data content (text) and any attributes („name=“value”‟ pairs) Documents can be simple, with straightforward nested markup, or more complicated with Schema or DTD (describe structure of the document)
Schema and DTD (Document Type Definition) Define the allowed parts of an XML document: The elements and attributes that can appear Data types, default and fixed values Identify child elements, and their order and number Whether an element is empty or includes text Schemas are the successors of DTDs Extensible to future additions, richer and more powerful, support data types and namespaces, written in XML XML Schema became a W3C recommendation in 2001
Stylesheets (CSS and XMLT) Transform XML into HTML Allow for document management benefits of XML, but readers don‟t need XML smarts in their browsers XMLT is an document processing language that uses XML source code Declares rules for processor to use when interpreting XML document
BrowsersCurrent versions of Internet Explorer, Firefox, Safari,Chrome, and Opera all support XML with CSS orXSLT stylesheets.Does not work with any versions of Netscape, IE6.0 or earlier, or early versions of Mozilla.
The DifferenceXML HMTL Designed to transport and Designed to display data store data Focuses on how data looks Focuses on what data isXHTML is “a reformulation of HTML 4 in XML1.0”
HTML5 Intended to include HTML and XHTML XHTML5 is an XML serialization of HTML5, meaning the data structure or object state is converted into a form that can be stored.