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Introduction to XML

Introduction to XML. Module Road Map. Assignment Road Map. Notice we have linked the conduit directly to the presentation layer. This is normally a bad idea!. Introduction to XML. How do we make all of these diverse technologies work together? Extensible Mark-up Language (XML)

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Introduction to XML

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  1. Introduction to XML

  2. Module Road Map

  3. Assignment Road Map Notice we have linked the conduit directly to the presentation layer. This is normally a bad idea!

  4. Introduction to XML • How do we make all of these diverse technologies work together? • Extensible Mark-up Language (XML) • Origins in SGML (Standard Generalised Mark-up Language) • Late 1980 early 90s Tim Berners-Lee working in Switzerland devised the first specification for HTML based on SGML

  5. Simple HTML Document • Tags mark-up the content… • Rendered as…

  6. Problems with HTML • The tags were defined as part of the language specification • Different browsers added new features to the language in order to compete • Browser wars

  7. The Marquee Tag

  8. World Wide Web Consortium (W3C) • Devise standards and software related to the World Wide Web • Greater standardisation was applied to HTML leading to XML

  9. Applying Standards • XML HTML, XHTML, Strict, Transitional • We must be good boys and girls • Apple, Opera and Mozilla devised an extension to HTML called Web Forms 2.0 • HTML 5

  10. Two Faces of the Web • HTML 5 – Human Being • XML – Systems • E.g. Netflix - Facebook

  11. XML • A meta-language - data about data • May be used to define other mark-up languages • XML may be used in many other non web related contexts (Office Documents) • Allows us to split data from presentation

  12. Media Centre Master • Tool to manage films saved as DivX files • Creation of scan folders • Communicates with the Internet Movie Database • Web service • Web page versus web document

  13. Viewed in Windows Media Centre

  14. Viewed at IMDB

  15. Tags in XML • XML doesn’t define a large range of tags • If we want to create a new tag in XML we don’t need to wait for a new version of the language • XML allows us define our own mark-up languages • XHTML (eXtensible HyperText Markup Language)

  16. XHTML • Document Type Definition contains a set of rules that define what are allowable tags in an XHTML file

  17. IMDB XML

  18. The XML Declaration • The top line of the file reads as follows... <?xml version="1.0" encoding="utf-8" standalone="yes"?> • XML Version (1.0 or 1.1 – only interested in 1.0) • Encoding – utf-8

  19. Encoding • Everything we see on a computer is internally represented as binary data • How do we translate the following? - 46, 41, 44, 45

  20. The Root Element • A tag that encloses all of the data in the file and must not be empty • XML file for 28 Days Later has a root element of <Title>

  21. Elements • <LocalTitle>28 Days Later</LocalTitle> • Opening tag <LocalTitle> • Closing tag </LocalTitle> • Data 28 Days Later

  22. Attributes and Values • Added to elements to include additional data • (Modified structure to illustrate attributes and values)

  23. Five Rules of XML • 1. Tag names are case sensitive • This is ok... <LocalTitle>28 Days Later</LocalTitle> • This is not... <LocalTitle>28 Days Later</Localtitle> • These are two different tags <localtitle>28 Days Later</localtitle> <LocalTitle>28 Days Later</LocalTitle>

  24. Five Rules of XML • 2. Every opening tag must have a closing tag • This is good... <LocalTitle>28 Days Later</LocalTitle> • This is bad... <LocalTitle>28 Days Later

  25. Five Rules of XML • 3. A nested tag pair cannot overlap another tag

  26. Five Rules of XML • 4. Attribute values must appear within quotes • Good... <FilmDetail Title="28 Days Later" IMDBrating="7.6" ProductionYear="2002"> • Bad... <FilmDetail Title=28 Days Later IMDBrating=7.6 ProductionYear=2002>

  27. Five Rules of XML • 5. Every document must have a root element

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