what information can we see…
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
What information can we see…
WWW2002The eleventh international world wide web conferenceSheraton waikiki hotelHonolulu, hawaii, USA7-11 may 20021 location 5 days learn interactRegistered participants coming fromaustralia, 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 nowOn the 7th May Honolulu will provide the backdrop of the eleventh
international world wide web conference. This prestigious event …Speakers confirmedTim berners-lee Tim is the well known inventor of the Web, …Ian FosterIan is the pioneer of the Grid, the next generation internet …
What information can a machine see…
…
…
…
Solution: markup with “meaningful” tags?
<name> </
name><location> </location>
<date> </date><slogan> </slogan><participants>
</participants>
<introduction>
</introduction>
<speaker> </speaker><bio> </
bio>…
Structured Web Documents in XML
XML, a language that lets one write structured Web documents with a user-defined vocabulary
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
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>
Imagine an intelligent agent trying to retrieve the authors of the particular book
From html From xml
XML allows to represent information that is also machine-accessible.
XML separates content from use and presentation.
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>
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
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)
Chemical Markup Language
Molecular Dynamics [Markup] Language (MoDL)StarDOM - Transforming Scientific Data into XMLBioinformatic 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 RFPProtein Extensible Markup Language (PROXIML)
The XML Language
An XML document consists of a prolog a number of elements and attributes
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">
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>
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”
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>
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“
/>
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>
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>
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
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"?>
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
The Tree Model of XML Documents: An Example
<email><head>
<from name="Michael Maher"
address="[email protected]"/><to name="Grigoris Antoniou"
address="[email protected]"/><subject>Where is your draft?</subject>
</head><body>
Grigoris, where is the draft of the paper you promised me
last week?</body>
</email>
The Tree Model of XML Documents: An Example
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
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?
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?
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)