An XML Introduction :An XML Introduction Next Generation Web Data


Overview :Overview An XML example -- so what’s so special about XML? The birth of the Web -- HTML HTML is not enough -- why? XML for universal data Common uses and applications


XML Example: test.xml :XML Example: test.xml Title of text XHTML Document Heading of Page here is a paragraph of text. I will include inside this paragraph a bunch of wonky text so that it looks fancy. Here is another paragraph with inline emphasized text, and absolutely no sense of humor. And here is another paragraph, this one containing an inline image, and a line break.


What do browsers do? :What do browsers do? Netscape 5 -- ignores the tags ... or so it seems ... Internet Explorer 5 -- shows a tree of elements.


The Birth of the Web :The Birth of the Web The HyperText Markup Language A simple language for distributing text All that other stuff URLs, HTTP, CGI ...


HTML Evolution :HTML Evolution Started with very few tags … Language evolved, as more tags were added forms tables fonts frames


HTML Problems :HTML Problems Desire for personalized tags Want to put data into HTML form mathematics, database entries, literary text, poems, purchase orders …. HTML just isn’t designed for that!


HTML Problems (2) :HTML Problems (2) Software processing Server management of data But -- HTML is so ill-formed, this is hard! HTML HTML HTML HTML HTML


Idea: Back to the Basics :Idea: Back to the Basics HTML was defined using SGML Standard Generalized Markup Language A meta-language for defining languages. Complex, sophisticated, powerful Idea: Use SGML


Languages based on SGML :Languages based on SGML SGML HTML TEI DocBook . . .


Problems with SGML :Problems with SGML Too complicated a language Rules are too strict Not good in a distributed environment Can’t mix different data together


Idea (2): “Webified” SGML :Idea (2): “Webified” SGML New eXtensible Markup Language: XML Can use XML to define new languages Distributes easily on the Web Can mix different types of data together


Basic XML Rules :Basic XML Rules Tags like in HTML, but ... Technical details Always need end tags Special empty-element tags Always quote attribute values


Like this example ….. :Like this example ….. Title of text XHTML Document Heading of Page ….. And here is another paragraph, this one containing an inline image, and a line break.


Evolution of XML :Evolution of XML Many XML languages, optimised for different roles MathML -- for mathematics SMIL -- for synchronised multimedia RDF -- for describing “things” XUL -- for describing the Navigator 5 user interface


MathML :MathML Designed to express semantics of maths Also can express layout Cut & paste into Maple, Mathematica x2 + 4x + 4 =0 x 2 + 4 &invisibletimes; x + 4 = 0


SMIL :SMIL Synchronised Multimedia Integration Language Integration of multimedia with text, audio, video Support in RealPlayer G2


SMIL Example :SMIL Example


XHTML: NextGen HTML :XHTML: NextGen HTML Title of text XHTML Document Heading of Page here is a paragraph of text. I will include inside this paragraph a bunch of wonky text so that it looks fancy. Here is another paragraph with inline emphasized text, and absolutely no sense of humor. And another paragraph, this one with an image, and a line break.


XHTML :XHTML Just like HTML, but based on XML rules Will support integration of different data into a single document


XHTML and other Data :XHTML and other Data Title of XHTML Document Heading of Page … MathML markup … more html stuff goes here … SMIL markup …


Other Use: Data Abstraction :Other Use: Data Abstraction XML as a universal format for data interchange Machines exchange data as XML-format messages Eliminates proprietary data formats Lots of XML processing software available


XML Messaging :XML Messaging


XML Messaging :XML Messaging Database Other DB Other DB Other DB Request/send data Request/send data


Example Message :Example Message Gold sprockel grommets, with matching hamster 12 …. Order something else …..


The XML Family Tree :The XML Family Tree SGML XML HTML TEI . . . . . .


Other Examples :Other Examples XUL: XML User Interface Language How Navigator 5 configures its interface RDF: Resource Description Framework For describing things Used by Netscape Open Catalog project to define Web accessible resources


Summary :Summary a framework for distributing data on the Web an integration tool for mixing different types of data a universal format for exchanging data between machines