XML and it's related X...'s

XML 1.0/1.1 (*.xml)

• Syntax rules for well-formed XML e.g. must have a single root element, closing tags required, proper tag nesting, case-sensitive, values in single or double quotes, all-in-one opening & closing tag allowed for empty elements with attributes, processing instructions and comments do not need closing tags, entity references must be declared (except for those built-in)
• CDATA can be used to display tags as text

<![CDATA[<person>Gareth</person>]]>

• Valid XML documents conform to semantic rules defined in a DTD or XML Schema

DTD vs. XML Schema

• DTD is non-XML like syntax, all declarations are global, unable to control kind of information elements can contain
• XML Schema was designed to overcome these weaknesses

DTD (*.dtd or internal to *.xml document)

    <!DOCTYPE people [



        <!ELEMENT person (name,age,weight/?,address)>



    <!ATTLIST name language(EnglishLatin)>



    ]>

XML Schema (*.xsd)

• Two types of content:
• Simple Content - elements that contain only text of built-in (type="xsd:string") or custom type
• Complex Content - elements that contain other elements or attributes
• Anotations can be used to describe parts of the schema
• Built-in types includes string, decimal, boolean, date, time, uri-reference, ISO language etc.
• Custom types allow Perl regex, inclusive/exclusive ranges, length, precision, lists, fixed and default values, choices, sequences etc.

XSLT (*.xslt)

• Used to analyse and transform XML documents into another format
• An XSLT processor converts XML into a node tree and uses the XSLT style sheet instructions to transform it
• Makes use of XPath to refer to individual parts of an XML document

XPath 1.0/2.0

• Used by XSLT, XSL-FO, XQuery, XInclude etc to refer to all or part of the text, data and values in XML documents

XInclude

• Allows XML files to include all or part of an external file

XQuery (XML Query)

• Equivalent of SQL to access, manipulate and return XML

XML Signature

• Defines syntax and processing rules for creating digital signatures in XML

XML Encryption

• Defines syntax and processing rules for encrypting XML

XPointer

• Can be used to address components of XML-based internet media

XSL-FO (XSL Formatting Objects)

• An XML-based page layout language, an XSL-FO processor can convert an XSL-FO document into another format e.g. a PDF

XLink (XML Linking Language)

• Used for creating HTML-like hyperlinks in XML