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What information can we see…

What information can we see…. WWW2002 The eleventh international world wide web conference Sheraton waikiki hotel Honolulu, hawaii, USA 7-11 may 2002 1 location 5 days learn interact Registered participants coming from

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What information can we see…

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  1. What information can we see… WWW2002 The eleventh international world wide web conference Sheraton waikiki hotel Honolulu, hawaii, USA 7-11 may 2002 1 location 5 days learn interact Registered participants coming from australia, canada, chile denmark, france, germany, ghana, hong kong, india, ireland, italy, japan, malta, new zealand, the netherlands, norway, singapore, switzerland, the united kingdom, the united states, vietnam, zaire Register now On the 7th May Honolulu will provide the backdrop of the eleventh international world wide web conference. This prestigious event … Speakers confirmed Tim berners-lee Tim is the well known inventor of the Web, … Ian Foster Ian is the pioneer of the Grid, the next generation internet …

  2. What information can a machine see… WWW2002 The eleventh international world wide web conference Sheraton waikiki hotel Honolulu, hawaii, USA 7-11 may 2002 1 location 5 days learn interact Registered participants coming from australia, canada, chile denmark, france, germany, ghana, hong kong, india, ireland, italy, japan, malta, new zealand, the netherlands, norway, singapore, switzerland, the united kingdom, the united states, vietnam, zaire Register now On the 7th May Honolulu will provide the backdrop of the eleventh international world wide web conference. This prestigious event … Speakers confirmed Tim berners-lee Tim is the well known inventor of the Web, … Ian Foster Ian is the pioneer of the Grid, the next generation internet …

  3. Solution: markup with “meaningful” tags? <name>WWW2002 The eleventh international world wide webcon</name> <location>Sheraton waikiki hotel Honolulu, hawaii, USA</location> <date>7-11 may 2002</date> <slogan>1 location 5 days learn interact</slogan> <participants>Registered participants coming from australia, canada, chile denmark, new zealand, the netherlands, norway, singapore, switzerland, the united kingdom, the united states, vietnam, zaire</participants> <introduction>Register now On the 7th May Honolulu will provide the backdrop of the eleventh prestigious Speakers confirmed</introduction> <speaker>Tim berners-lee</speaker> <bio>Tim is the well known inventor of the Web,</bio>…

  4. Structured Web Documents in XML XML, a language that lets one write structured Web documents with a user-defined vocabulary

  5. Web page which contains information about a particular book in html <h2>Nonmonotonic Reasoning: Context-Dependent Reasoning</h2> <i>by <b>V. Marek</b> and <b>M. Truszczynski</b></i><br> Springer 1993<br> ISBN 0387976892

  6. A typical representation in xml <book> <title> Nonmonotonic Reasoning: Context-Dependent Reasoning </title> <author>V. Marek</author> <author>M. Truszczynski</author> <publisher>Springer</publisher> <year>1993</year> <ISBN>0387976892</ISBN> </book>

  7. Imagine an intelligent agent trying to retrieve the authors of the particular book • From html • From xml

  8. XML allows to represent information that is also machine-accessible. • XML separates content from use and presentation.

  9. Another Example <h2>Relationship matter-energy</h2> <i> E = M × c2 </i> <equation> <meaning>Relationship matter-energy</meaning> <leftside> E </leftside> <rightside> M × c2 </rightside> </equation>

  10. XML is a meta-language: it does not have a fixed set of tags, but allows users to define tags of their own. • applications on the WWW must agree on common vocabularies if they need to communicate and collaborate • Communities and business sectors are in the process of defining their specialized vocabularies, creating XML applications

  11. mathematics (MathML) • bioinformatics (BSML) • human resources (HRML) • astronomy (AML) • news (NewsML) • investment (IRML) • SBML (System Biology) • Bioinformatic Sequence Markup Language (BSML) • MicroArray and Gene Expression Markup Language (MAGE-ML)

  12. Chemical Markup Language • Molecular Dynamics [Markup] Language (MoDL) • StarDOM - Transforming Scientific Data into XML • Bioinformatic Sequence Markup Language (BSML) • BIOpolymer Markup Language (BIOML) • CellML • Gene Expression Markup Language (GEML) • GeneX Gene Expression Markup Language (GeneXML) • Genome Annotation Markup Elements (GAME) • Microarray Markup Language (MAML) • XML for Multiple Sequence Alignments (MSAML) • Systems Biology Markup Language (SBML) • OMG Gene Expression RFP • Protein Extensible Markup Language (PROXIML)

  13. The XML Language An XML document consists of • a prolog • a number of elements • and attributes

  14. Prolog of an XML Document The prolog consists of • an XML declaration and • an optional reference to external structuring documents <?xml version="1.0" encoding="UTF-16"?> <!DOCTYPE book SYSTEM "book.dtd">

  15. XML Elements • The “things” the XML document talks about • E.g. books, authors, publishers • An element consists of: • an opening tag • the content • a closing tag <lecturer>David Billington</lecturer>

  16. XML Elements (continue) • Tag names can be chosen almost freely. • The first character must be a letter, an underscore, or a colon • No name may begin with the string “xml” in any combination of cases • E.g. “Xml”, “xML”

  17. Content of XML Elements • Content may be text, or other elements, or nothing <lecturer> <name>David Billington</name> <phone> +61 − 7 − 3875 507 </phone> </lecturer> • If there is no content, then the element is called empty; it is abbreviated as follows: <lecturer/> for <lecturer></lecturer>

  18. XML Attributes • An empty element is not necessarily meaningless • It may have some properties in terms of attributes • An attribute is a name-value pair inside the opening tag of an element <lecturer name="David Billington" phone="+61 − 7 − 3875 507“ />

  19. XML Attributes: An Example <order orderNo="23456" customer="John Smith" date="October 15, 2002“> <item itemNo="a528" quantity="1"/> <item itemNo="c817" quantity="3"/> </order>

  20. The Same Example without Attributes <order> <orderNo>23456</orderNo> <customer>John Smith</customer> <date>October 15, 2002</date> <item> <itemNo>a528</itemNo> <quantity>1</quantity> </item> <item> <itemNo>c817</itemNo> <quantity>3</quantity> </item> </order>

  21. XML Elements vs Attributes • Attributes can be replaced by elements • When to use elements and when attributes is a matter of taste and need • But attributes cannot be nested

  22. Further Components of XML Docs • Comments • A piece of text that is to be ignored by parser • <!-- This is a comment --> • Processing Instructions (PIs) • Define procedural attachments • <?stylesheet type="text/css" href="mystyle.css"?>

  23. Well-Formed XML Documents • Syntactically correct documents • Some syntactic rules: • Only one outermost element (called root element) • Each element contains an opening and a corresponding closing tag • Tags may not overlap • <author><name>Lee Hong</author></name> • Attributes within an element have unique names • Element and tag names must be permissible

  24. The Tree Model of XML Documents: An Example <email> <head> <from name="Michael Maher" address="michaelmaher@cs.gu.edu.au"/> <to name="Grigoris Antoniou" address="grigoris@cs.unibremen.de"/> <subject>Where is your draft?</subject> </head> <body> Grigoris, where is the draft of the paper you promised me last week? </body> </email>

  25. The Tree Model of XML Documents: An Example

  26. The Tree Model of XML Docs • The tree representation of an XML document is an ordered labeled tree: • There is exactly one root • There are no cycles • Each non-root node has exactly one parent • Each node has a label. • The order of elements is important • … but the order of attributes is not important

  27. XML is not enough to ensure valid data structure! • Any XML document which conforms to the XML syntax (such as every tag must have a corresponding closing tag is considered) to be well-formed • However, this does not mean that all the structure of the data is what you wanted. For instance you may want to enforce: • That a particular data field is present for each child • Data fields in each child appear in the same order • That a data field may not be present more than once in a child node • How machines know about structure they process?

  28. Issues • Validation and Interoperability • How application can verify whether the data you receive from the outside world? • Is xml document follows the specified structure? • Is xml document follows the restrictions on the elements and attributes? • How all the xml document follows that particular structure?

  29. Structuring XML Documents • An XML document is valid if • it is well-formed • respects the structuring information it uses • There are two ways of defining the structure of XML documents: • DTDs (the older and more restricted way) • XML Schema (offers extended possibilities)

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