The Web of Data for E-Commerce in Brief

A Hands-on Introduction to the GoodRelations Ontology, RDFa, and Yahoo! SearchMonkey

October 25, 2009

Westfields Conference Center near Washington, DC, USA

Martin Hepp Universität der Bundeswehr München, Munich, Germany

Richard Cyganiak Digital Enterprise Research Institute (DERI), Ireland

08:30-10:30 Overview and Motivation: Why the Web of Data is Now 30’

Quick Review of Prerequisites 15’ The GoodRelations Ontology: E-Commerce on the Web of Data 75’

10:30-10:45 Coffee Break

10:45-12:30 RDFa: Bridging the Web of Documents with the Web of Data 45’

Expressing GoodRelations in RDFa: A Running Example 30’ GoodRelations – Advanced Topics 30’

12:30-13:30 Lunch Break

13:30-16:00 Hands-on Exercise: Annotating a Web Shop 60’

Querying the Web of Data for Offerings – SPARQL 15’ Querying the Web of Data – Exercises 15’

16:00-16:30 Coffee Break

16:30-18:00 Publishing Semantic Web Data: Make Your RDF Available 30’

Yahoo SearchMonkey and Yahoo BOSS 45’ Discussion, Conclusion, Feedback Round 15’

2

Logistics

Quick Review of Prerequisites

Martin Hepp

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Learning Goals

In this part, we will

• make sure all participants have sufficient

knowledge of related topics,

and

• show how to install the Twinkle software.

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Prerequisites for the Tutorial

• Markup Languages

– XML, HTML, XHTML

• Semantic Web Basics

– URIs

– RDF

– RDFS and OWL

• Tooling and

Infrastructure

– Editors

– Repositories and

Reasoners

– Frameworks / APIs

• Linked Data

Principles

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Core Semantic Web Technology Pillars • Global Identifiers: URIs for everything

• Data Model: RDF - A data model for exchanging conceptual graphs based

on triples

– Compatible with the design principles of the Web (especially with its distributed

nature)

– Triple: (Subject, Predicate, Object)

– Exchange syntax: RDF/XML, N3, RDFa etc.

• Ontology Languages: RDFS and OWL - formal languages that help

reduce ambiguity and codify implicit facts

– foo:human rdfs:subClassOf foo:mammal

• Query Language & Interface: SPARQL - standardized query language

and endpoint interface for RDF data

• LOD Principles: Best practices for keeping the current Web and the Web of Data compatible

6

Global Identifiers: URIs for Everything

1. Make clear whether

you are referring to

something or its representation. URI1: Page

URI2-x: Data items

2. Distinct URIs for

distinct data items

• Web page

• Company

• Product

• Price information

• etc.

7

Creating URIs for Everything

• Web of Documents

– http://www.myshop.com/about.html

• Web of Linked Data

– http://www.myshop.com/about.html (Page)

– http://www.myshop.com/about.html#BusinessEntity

– http://www.myshop.com/about.html#Product

– http://www.myshop.com/about.html#Warranty

8

RDF vs. RDF/XML, N3/Turtle, RDFa

• RDF – Resource Description Framework

– Basically, the data model of representing

conceptual graphs in the form of triples

subject predicate object <http://foo.org/joe> <http://vocab.at/likes> <http://foo.org/linda>.

<http://foo.org/joe> <http://vocab.at/name> “Joe Miller”.

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Syntaxes: RDF/XML, N3/Turtle, RDFa

• RDF/XML – RDF in XML

• N3/Turtle – Human-readable RDF

• RDFa – RDF embedded in XHTML/HTML

subject predicate object <http://foo.org/joe> <http://vocab.at/likes> <http://foo.org/linda>.

<http://foo.org/joe> <http://vocab.at/name> “Joe Miller”.

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Turtle Syntax for RDF

http://www.dajobe.org/2004/01/turtle/

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RDFa = Complete RDF

N3/Turtle

RDF/XML

RDFa

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This is not widely known!

Simplified Process of Using the

Semantic Web • Find or create ontology / vocabulary

– “Ontology Engineering”

• Create data expressed using that vocabulary

– “Ontology Population” / “Knowledge Base

Population” / “Annotating Data” / “RDFizing”

• Publish the data

• Query / reuse / combine the data

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Tooling and Infrastructure

Editors

Repositories and Reasoners

Frameworks / APIs

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Editors

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Parsers, Repositories, Reasoners

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RDF/XML Reasoner

Implicit Model

Explicit

Model

N3

XHTML

+RDFa

Parser Query

Repository

Frameworks, Libraries, and APIs

• Jena Semantic Web Framework: Java

framework for building Semantic Web

applications.

– http://jena.sourceforge.net/

• RDFLib: Python library for working with RDF

– http://www.rdflib.net/

• Redland RDF Libraries (aka librdf): C-based

library with APIs in Perl, Python, Tcl and Java.

– http://librdf.org

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Linked Data Principles

• Linked data principles, by Tim Berners-

Lee, ca. 2006 – Use URIs to identify things (anything, not just

documents)

– Use HTTP URIs – globally unique names, distributed

ownership – allows people to look up things

– Provide useful information in RDF – when someone

looks up a URI

– Include RDF links to other URIs – to enable

discovery of related information

18

Twinkle

Installations and Usage

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Twinkle: A SPARQL Query Tool

http://www.ldodds.com/projects/twinkle/ 25.10.2009 20

Twinkle: Installation

• Requires Java 1.5 or higher

• Download the distribution and unzip it into a new

directory:

– http://www.ldodds.com/projects/twinkle/twinkle-2.0-bin.zip

• Replace the file config.n3 in the "etc" subdirectory by the

file available at

– http://www.ebusiness-unibw.org/pubwiki/images/8/84/

Config.n3.txt

– Rename it to config.n3 after downloading

• Open a command prompt and execute the following:

– java -jar twinkle.jar

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Thank you.

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