An XML Introduction Next Generation Web Data Ian GRAHAM Centre for Academic Technology Tel: Talk:

Overview zAn XML example y -- so what’s so special about XML? zThe birth of the Web -- HTML zHTML is not enough -- why? zXML for universal data zCommon uses and applications

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 <img src="image.gif" alt="waste of time" /> inline image, and a line break.

It Looks Like HTML …. zSort of …. zTags look just like HTML tags (although XML lets you ‘create’ your own) zThe “red bits” are special XML stuff (we will discuss them later) zIt’s got.xml at the end

The Birth of the Web zThe HyperText Markup Language yA simple language for distributing text zAll that other stuff yURLs, HTTP, CGI...

HTML Evolution zStarted with very few tags … zLanguage evolved, as more tags were added yforms ytables yfonts yframes

HTML Problems zDesire for personalized tags zWant to put data into HTML form ymathematics, database entries, literary text, poems, purchase orders …. zHTML just isn’t designed for that!

HTML Problems (2) zSoftware processing yServer management of data zBut -- HTML is so ill- formed, this is hard! HTML

Idea: Back to the Basics zHTML was defined using SGML yStandard Generalized Markup Language yA meta-language for defining languages. zComplex, sophisticated, powerful zIdea: Use SGML

Languages based on SGML SGML HTMLTEIDocBook...

Problems with SGML zToo complicated a language zRules are too strict yCan’t distribute ‘loosely’ formatted text (like HTML) zNot good in a distributed environment zCan’t mix different data together yCan’t add arbitrary tags

Idea (2): “Webified” SGML zNew eXtensible Markup Language: XML zCan use XML to define new languages zDistributes easily on the Web zCan mix different types of data together ycan easily add new tags, and tell a browser what to do with them.

Basic XML Rules zTags like in HTML, but... zTechnical details yTag names are case-sensitive yAlways need end tags ySpecial empty-element tags yAlways quote attribute values

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.

XML Things z ySays that this is an XML document z ySays that the meaning of the tags inside (and including) the html “element” are defined here.

Evolution of XML zMany XML languages, optimised for different roles yMathML -- for mathematics ySMIL -- for synchronised multimedia yRDF -- for describing “things” yXUL -- for describing the Navigator 5 user interface

MathML zDesigned to express semantics of maths zAlso can express layout zCut & paste into Maple, Mathematica z x 2 + 4x + 4 =0 x &invisibletimes; x + 4 = 0

SMIL zSynchronised Multimedia Integration Language zIntegration of multimedia with text, audio, video zSupport in RealPlayer G2

SMIL Example <region id="AnimChannel1" title="AnimChannel1" left="0" top="0" height="265" width="280" fit="hidden"/> <animation src="otscompfin.swf" id="Animation" region="AnimChannel1" title="Animation" fill="freeze"/>

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 <img src="image.gif" alt="waste of time" /> image, and a line break.

XHTML zJust like HTML, but based on XML rules zWill support integration of different data into a single document

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

Displaying XML zMore complicated than HTML yXML represents data only, not how it looks yNeed extra instructions (a “style sheet” document) to define how things should look

What Browsers Do Now? yNetscape 5 -- ignores the tags... or so it seems... yInternet Explorer 5 -- shows a tree of elements yNavigator 4, Internet Explorer 4 xUggh…… (can’t handle it)

Other Use: Data Abstraction zXML as a universal format for data interchange yMachines exchange data as XML-format messages yEliminates proprietary data formats yLots of XML processing software available

XML Messaging Factory Supplier Place order Response

XML Messaging Database Other DB Request/send data

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

The XML Family Tree SGML XML HTMLTEI XHTML SMIL MathML SpeechML RDF XUL

Other Examples zXUL: XML User Interface Language yHow Navigator 5 configures its interface zRDF: Resource Description Framework yFor describing things yUsed by Netscape Open Catalog project to define Web accessible resources

Summary za framework for distributing data on the Web zan integration tool for mixing different types of data za universal format for exchanging data between machines

An XML Introduction Next Generation Web Data Ian GRAHAM Centre for Academic Technology Tel: Talk: