A U eXtensible Markup Language (XML) Professor J. Alberto Espinosa ITEC 334 Fall 2008 Computer Programming in the Web Era

p.2 Web Based Languages Hyper Text Markup Language (HTML) –Text based description language used to create Web pages, which is interpreted by Web Browsers –Text (data) is “marked up” with –e.g. Hello!! eXtensible Markup Language (XML) –Like HTML, but used to specify/exchange data –Text (data) is “marked up” with (like HTML) –But tags are pre-defined for each application –e.g Espinosa –XML processors retrieve and process the data (a browser is an HTML processor) HTML and XML are NOT software languages !! They are page description languages

p.3 Basic bread Flour Yeast Water Salt Mix all ingredients together, and knead thoroughly. Cover with a cloth, and leave for one hour in warm room. Knead again, place in a tin, and then bake in the oven. Example: Baking Bread with XML

p.4 1 Alberto Espinosa Professor American University Information Technology Looks tired, needs vacation 2 Gwanhoo Lee Professor American University Information Technology He teaches the other 2 MIS sections 3 Jill Klein Professor American University Information Technology She teaches the MBA MIS course Another XML Example Can you draw a table that contains the following data?

p.5 XML Data After Importing into a Database Customers

p.6 Business to Business E-Commerce Example using XML Internet Supplier Buyer DBMS (e.g., Oracle) SELECT query XML Processor XML Document (e.g., Purchase Order) DBMS (e.g., MS SQL Server) INSERT query XML Processor XML Document (e.g., Purchase Order) Query results

p.7 More About XML Document Type Definition (DTD) Documents –Document used to define the meaning of tag used in a particular XML document –A DTD can be embedded in the XML file itself –Or in a separate.dtd file, which can be used in multiple XML files –Specific industries (e.g., automotive, insurance, etc.) have standard DTD files used to exchange data (e.g. orders, invoices, catalogs) between buyers and suppliers – XML programmers for these industries need to be familiar with these DTD’s eXtensible Stylesheet Language (XSL) –Like Cascading Stylesheets (CSS) –To format data displays on the browser