Notes

Outline

A Brief History of Markup 1969 - Generalized Markup Language (GML)

Why XML is so important:

XML structure and validity HTML vs XML/XHTML  single root element  nested tags  tag structure  quoted values  entity references  DOCTYPE declaration  case sensitive  default namespace

DTD (Document Type Definition)  validates your document  makes sure it is structured correctly  makes sure all tags are used in the proper manner  DTDs do not tell you  how many instances of each kind of element appears  what the character data looks like  the semantic meaning of an element

XML Schema  Goal was to be more expressive than DTD and written in XML  XML Schema allows you to define:  the structure  the content  the semantics

XML Namespaces  user defined prefix associated and pre-pended to an element  avoids name collisions with other elements  similar to Java packages

XML Programming

XML Parsers (example: Apache Xerces)  validating  non-validating

XML Standard Interfaces SAX (Simple API for XML) - stream based - sequential access DOM (Document Object Model) - tree based - random access

SAX vs DOM A case study: Apache’s Cocoon Project DOM tree based rich API use of XPath simple to use read and write seriously resource intensive!!!! not scaleable SAX stream based simple API cannot use XPath * difficult to use read only…but can use filters very fast, not resource intensive very scaleable

XPath  non-XML syntax used for expressions that identify particular nodes and groups of nodes in a document  XPath 1.0 defines 27 built-in functions for use in XPath expressions

XML Transformations XSL (eXtensible Stylesheet Language) XSLT XSL-FO XML Processor (example: Apache’s Xalan)

XSLT eXtensible Stylesheet Transformations XML to HTML XML to XML

XSL-FO XSL Formatting Objects XML to PDF XML to PostScript

Other XML Technologies SVG RDF XUL XQL XML-RPC SOAP