Infromation Reprentation,Structured Data and Semantics

Yogendra Tamang

070-MSCS-670

OUTLINE

• XML, DTD and XML Schema, XSLT

• Meta data Standards.

• Information Representation in Semantic Web• RDF, RDFS

• Syntactic Formats• RDF/XML, N-triples, Turtles etc.

• Embedded Formats• RDFs, Microformats, eRDF, HTML5, GRDDL, SPARQL

XML

XML DocumentsEpilogue

Thing! Elements

Prolog

XML Declaration and

Reference

Tag, Attributes

and Content

<?xml version="1.0" encoding="UTF-16"?><!DOCTYPE book SYSTEM "book.dtd">

<lecturer>David Billington</lecturer>

XML

• Comments and Processing Instructions

<!-- This is a comment -->

<?stylesheet type="text/css" href="mystyle.css"?>

DTD and XML Schema

• Used for defining the structure • what values an attribute may take

• which elements may or must occur within other elements, etc.

<lecturer>

<name>David Billington</name>

<phone> +61 − 7 − 3875 507 </phone>

</lecturer>

<!ELEMENT lecturer (name,phone)>

<!ELEMENT name (#PCDATA)>

<!ELEMENT phone (#PCDATA)>

DTDDisjunctions:

<!ELEMENT lecturer (name|phone)>

<!ELEMENT lecturer((name,phone)|(phone,name))>

DTD<order orderNo="23456" customer="John Smith" date="October 15, 2002">

<item itemNo="a528" quantity="1"/>

<item itemNo="c817" quantity="3"/>

</order><!ELEMENT order (item+)>

<!ATTLIST order orderNo ID #REQUIRED

customer CDATA #REQUIRED

date CDATA #REQUIRED>

<!ELEMENT item EMPTY>

<!ATTLIST item itemNo ID #REQUIRED

quantity CDATA #REQUIRED

comments CDATA #IMPLIED>

XML Schema<schema http://www.w3.org/2000/10/XMLSchema version="1.0">

Element and Attribute Types using Data Types

• Numerical data types: integer, Short etc.

• String types: string, ID, IDREF, CDATA etc.

• Date and time data types: time, Month etc.

• User defined(Simple and Comlpex)

XML Namespaces and XPATH

• Form:xmlns:prefix="location“

• XPATH:Operates on Tree data model and is core for XML query lanaguage

XSLT

•XSLT specifies rules with which an input XML document is transformed to• another XML document• an HTML document • plain text

RDF

• It provides a uniform framework for interchange of data and metadata between applications

•XML does not provide any means of talking about the semantics (meaning) of data

•Object-Attribute-Value

RDF

• Fundamental Concepts:• resources

• properties

• statements

Statements

• Triples

• (x, P, y) P(x, y)

RDFS Core Classes

• rdfs:Resource, the class of all resources• rdfs:Class, the class of all classes• rdfs:Literal, the class of all literals (strings) • rdf:Property, the class of all properties.• rdf:Statement, the class of all reified statements

RDFS Core Properties• rdf:type, which relates a resource to its class

• The resource is declared to be an instance of that class

• rdfs:subClassOf, which relates a class to one of its superclasses• All instances of a class are instances of its superclass

• rdfs:subPropertyOf, relates a property to one of its superproperties

• rdfs:domain,

• rdfs:range,

RDF Sparql Query

• SPARQL is based on matching graph patterns

• Example:

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>

SELECT ?c

WHERE

{

?c rdf:type rdfs:Class .

}

RDFa

• RDFa is an extension to HTML5 that helps you markup things like People, Places, Events, Recipes and Reviews. Search Engines and Web Services use this markup to generate better search listings and give you better visibility on the Web, so that people can find your website more easily

Microformats

• microformats are a set of simple, open data formats built upon existing and widely adopted standards

MicroFormats Tools and Code generators

Ntriples

Green Turtle RDFa

Green Triples

• an implementation of RDFa 1.1 for browsers

• When triples are discovered in a web page, a little green turtle will appear in the address bar. If you click on that turtle, you can

view the triple graph.

References

• “Semantic Web Primer”, Grigoris Antoniou, Frank van Harmelen

• http://rdfa.info/

• https://code.google.com/p/green-turtle/

• http://microformats.org/wiki/about