XML Prashant Karmarkar Brendan Nolan Alexander Roda

What is XML?  A framework for defining markup languages  No fixed collection of markup tags  each XML language is targeted at its own application domain  there is a common set of generic tools for processing documents

HTML vs. XML?  HTML  fixed tag set and tag semantics  XML  defines no tag set or semantics  provides a facility to define tags and the structural relationships between them  XML is not a replacement for HTML  HTML should ideally just be another XML language  XHTML is just that

Why is XML useful?  XML allows you to create your own markup language  XML data can be presented in a variety of ways  CSS and XSL  Separates data from presentation instructions which enables changing the presentation without altering underlying data  XML is well suited as a means of transferring data across platforms  Businesses store data in a different structure using different software tools  EDI current solution – expensive and not practical except for largest companies  XML provides a low cost, low barriers to entry solution for having a universal data format that makes communication across heterogeneous platforms possible

Example XML Applications XHTML: Hello world! Hello world! foobar foobar CML: C O H H H H C O H H H H

The XML Schema More Rigid than HTML More Rigid than HTML Uses validation Uses validation Comprised of Comprised of ElementsElements AttributesAttributes ValuesValues TallTales.xml – Basic Example TallTales.xml – Basic Example Basic Schema Basic Schema Organization of data Organization of data

Processing Schemas  Example of CSS processing  Css stylesheets can control:  Font  Color of text  Positioning of content  Note the declaration.  TallTales.xml---->Through---->css file

Processing xml cont.  Css files not sufficient  XSL allows for  Reuse of document data  Calculate quantities and store values  Generate dynamic text  Takes an initial schema (tree) and creates another tree. (“Results Tree”)

XSL Continued  XSL consist of three languages:  XSLT – Transforms vocabulary  XSL FO – Formats a schema  XPATH – An expression language  Used Vehicle example

Creating your own  Data modeling enables custom language  Two Approaches  DTD – DOCUMENT TYPE DEFINITION  XSD –XML SCHEMA DOCUMENTS  Insure validation

Web Services Self Describing Self-Contained Modular Applications PublishedLocatedInvoked Over the web

What are Web Services, anyway? TCP/IP - Universal Networking Protocol HTML – Universal User Interface Java –Universal Coding Language XML – Language for Universal Data Open, Cross Platform Standards

Where is the Web heading More dynamic content Bandwidth is getting cheaper Storage is getting cheaper Pervasive Computing is becoming more important

Where do Web Services fit in? Web Services can be used to combine the content from various sources Web Service can now deliver types of content (streaming video or audio ) Web Service can deal with massive amounts of data intelligently (Databases, LDAP directories, caches and load balancing factors) Users need not require to run traditional browsers on some version of Windows.Web Service can be used to serve all sorts of devices, platforms and browser types

Enabling Technologies for Web Services XMLSOAP