2004.11.04 - SLIDE 1IS 202 - FALL 2004 Lecture 20: Semantic Web and RDF Prof. Ray Larson & Prof....

2004.11.04 - SLIDE 1IS 202 - FALL 2004

Lecture 20: Semantic Web and RDF

Prof. Ray Larson & Prof. Marc Davis

UC Berkeley SIMS

Tuesday and Thursday 10:30 am - 12:00 am

Fall 2004

SIMS 202:

Information Organization

and Retrieval

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Lecture Contents

• Review of Last Time– Phone Project Introduction

• Semantic Web and RDF– Semantic Web– RDF– Discussion Questions

• Action Items for Next Time

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Lecture Contents




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The Media Metadata Opportunity

• Vastly more media will be produced• Without ways to manage it (metadata

creation and use) we lose the advantages of digital media

• Most current approaches are insufficient and perhaps misguided

• Great opportunity for innovation and invention

• Need interdisciplinary approaches to the problem

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Capture+Processing+Interaction+Network

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Camera Phones as Platform

• Media capture (images, video, audio)

• Programmable processing using open standard operating systems, programming languages, and APIs

• Wireless networking• Personal information

management functions• Rich user interaction modalities• Time, location, and user

contextual metadata

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Phone Project Overview

• In this project we will be creating, sharing, and reusing mobile media and metadata

• You and your Project Group will design application use scenarios and develop and refine metadata frameworks for your photos

• We will be using the Nokia 7610 mobile media phone and software developed by Garage Cinema Research

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Phone Project Overview

• In the SIMS 202 Phone Project you and your Project Group will– Experience the actual process of information

organization and retrieval (especially as regards metadata creation and use)

– Work in small, focused teams performing a variety of tasks in image acquisition, description, and application design

– Develop an ongoing resource for SIMS (an annotated photo database) that can be used for internal research and teaching, as well as for external promotional and informational purposes

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Phone Project Requirements

• Create engaging and useful application scenarios and photos for use by your team and the entire class– The photos you take and the applications you will

design to use them should be interesting and useful to you and your colleagues

• Create a shared, reusable resource of annotated photos– Design your metadata such that all photos are

accessible not only for the needs of your particular application, but also for the reusability of your photos and metadata by other applications

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Phone Project Assignments

DATE ASSIGNED DUE

Tuesday, November 2Cameraphone Use Scenario –

Application Idea

Thursday, November 4

Tuesday, November 9 Photo Metadata DesignCameraphone Use Scenario –

Application Idea


Tuesday, November 16 Photo Metadata Design

Thursday, November 18 Metadata Revision

Tuesday, November 23 Photo Capture and Annotation Metadata Revision


Tuesday, November 30 Project Presentations Photo Capture and Annotation

Thursday, December 2

Tuesday, December 7 Project Presentations

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Phone Project Assignments

• Cameraphone Use Scenario – Application Idea (Assignment 5)– You will brainstorm and storyboard an

application for a mobile media device that accesses a server and facilitates the creation, sharing, and reuse of media and metadata. You will develop user personas and scenarios of how the application works and how the user experiences it. The applications you will design should be interesting and useful to you and your colleagues.

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Lecture Contents




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Semantic Web

• The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries. It is a collaborative effort led by W3C with participation from a large number of researchers and industrial partners. It is based on the Resource Description Framework (RDF), which integrates a variety of applications using XML for syntax and URIs for naming.

• "The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation." -- Tim Berners-Lee, James Hendler, Ora Lassila, The Semantic Web, Scientific American, May 2001

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Question for Thought

• What does it mean for Semantic Web statements to be “semantic,” i.e., to have “meaning”?

• What is the semantic the difference between these two RDF triples:– ex:index.html dc:creator exstaff:85740– fy:joefy.iunm ed:dsfbups fytubgg:85740

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Semantic Web

• Usage metaphors– Agents and semantics

• From HTML tags to RDF semantics– RDF

• Triples (Subject – Predicate - Object) to express relations– “Marc Davis” “Co-Teach” “IS202”– “Marc Davis” “is-a” “Assistant Professor”

– URIs• Uniform Resource Identifiers to unambiguously reference

unique things (objects, people, documents, ideas, etc.)

– Ontologies• Graphs of RDF triples to enable inferencing about entities

and relations

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Lecture Contents




Animated GIF from:www.cs.kent.ac.uk/ people/rpg/pjm2/

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Resource Description Framework (RDF)• The Resource Description Framework (RDF) is a

language for representing information about resources in the World Wide Web

• It is particularly intended for representing metadata about Web resources, such as the title, author, and modification date of a Web page, copyright and licensing information about a Web document, or the availability schedule for some shared resource

• However, by generalizing the concept of a "Web resource", RDF can also be used to represent information about things that can be identified on the Web, even when they cannot be directly retrieved on the Web– Examples include information about items available from on-line

shopping facilities (e.g., information about specifications, prices, and availability), or the description of a Web user's preferences for information delivery

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XML Trees vs. RDF Graphs

• XML is (basically) tree structured

• RDF is graph structured

1

2 3 4

5 6 7

1

2 3 4

5 6 7

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RDF is Triples

• “http://www.example.org/index.html has a creator whose value is John Smith”– The subject is the URL

http://www.example.org/index.html• The thing the statement describes (the Web page, in this

case)

– The predicate is the word creator• A specific property (creator, in this case) of the thing the

statement describes

– The object is the phrase John Smith• The thing the statement says is the value of this property

(who the creator is), for the thing the statement describes

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Controlling the Name Space: URIs

• Uniform Resource Identifier (URIs) uniquely identify:– Network-accessible things, such as an

electronic document, an image, a service (e.g., "today's weather report for Los Angeles"), or a group of other resources

– Things that are not network-accessible, such as human beings, corporations, and bound books in a library

– Abstract concepts that do not physically exist, such as the concept of a "creator"

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RDF and URIs

• Like HTML, this RDF/XML is machine processable and, using URIs, can link pieces of information across the Web

• However, unlike conventional hypertext, RDF URIs can refer to any identifiable thing, including things that may not be directly retrievable on the Web (such as the person Eric Miller)

• The result is that in addition to describing such things as Web pages, RDF can also describe cars, businesses, people, news events, etc.

• In addition, RDF properties themselves have URIs, to precisely identify the relationships that exist between the linked items

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Visualization of RDF Graph

• "there is a Person identified by http://www.w3.org/People/EM/contact#me, whose name is Eric Miller, whose email address is [email protected], and whose title is Dr."

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URIs and Literals in RDF Graph• URIs (statements in green ovals and other

http://www.w3.org/... statements)– Individuals, e.g., Eric Miller

• http://www.w3.org/People/EM/contact#me

– Kinds of things, e.g., Person• http://www.w3.org/2000/10/swap/pim/contact#Person

– Properties of those things, e.g., mailbox• http://www.w3.org/2000/10/swap/pim/contact#mailbox

– Values of those properties, e.g. mailto:[email protected]

• Literals (statements in yellow rectangles)– RDF also uses character strings like "Eric Miller" and values

from other datatypes such as integers and dates as the values of properties

– Note from Prof. Davis: be careful about literals—most things are better expressed as URIs

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RDF-XML for RDF Graph

<?xml version="1.0"?>

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:contact="http://www.w3.org/2000/10/swap/pim/contact#">

<contact:Person rdf:about="http://www.w3.org/People/EM/contact#me">

<contact:fullName>Eric Miller</contact:fullName>

<contact:mailbox rdf:resource="mailto:[email protected]"/>

<contact:personalTitle>Dr.</contact:personalTitle>

</contact:Person>

</rdf:RDF>

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RDF Triples for an Address

• exstaff:85740 exterms:address "1501 Grant Avenue, Bedford, Massachusetts 01730" . – exstaff:85740 exterms:address exaddressid:85740 . – exaddressid:85740 exterms:street "1501 Grant

Avenue" . – exaddressid:85740 exterms:city "Bedford" . – exaddressid:85740 exterms:state "Massachusetts" .

– exaddressid:85740 exterms:postalCode "01730" .

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Visualization of RDF Address Data

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Declaring Namespaces: xmlns 1. <?xml version="1.0"?> 2. <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" 3. xmlns:dc="http://purl.org/dc/elements/1.1/" 4. xmlns:exterms="http://www.example.org/terms/"> 5. <rdf:Description rdf:about="http://www.example.org/index.html"> 6. <exterms:creation-date>August 16, 1999</exterms:creation-date> 7. <dc:language>en</dc:language> 8. <dc:creator rdf:resource="http://www.example.org/staffid/85740"/> 9. </rdf:Description>

10. </rdf:RDF>

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Lecture Contents




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Discussion Questions

• Matthew Rothenberg on “Semantic Web”– The original web had "purposely minimal"

requirements for documents, and it was exceedingly easy for anyone to create a document by hand. In contrast, the semantic web relies upon documents that consist of fairly complex and logical markup. How can we expect *everyday document creators* (not SIMS graduates) to provide all of this markup, and maintain the simplicity that made the WWW spread so quickly? What types of tools would assist in this?

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• Matthew Rothenberg on “Semantic Web”– Q. SAT word analogies: The WWW is to

Browser as the Semantic Web is to _______.A. (Agent)Follow-up: What do you think are some of the fundamental differences between a browser paradigm and an agent paradigm?

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• Colleen Whitney on “Semantic Web”– Given the current security climate, how viable

do you think the Pete and Lucy scenario (trusted agents arranging appointment times) is at present?

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• Colleen Whitney on “Semantic Web”– The authors present a tantalizing vision for

the future. What will have to happen in order for momentum to built toward realizing this vision? What are the barriers and incentives?

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• Sarah Poon on “RDF Primer”– RDF is used to express statements about

resources, such as web pages, people, and events. How could we use RDF in the phone project? Why might we use RDF for information sharing over direct access to a database or using a regular XML file?

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• Sarah Poon on “RDF Primer”– What RDF classes might be useful in the

phone project? What are the possible instances and properties of these classes?

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• Mike Wooldridge on “RDF Primer”– The article mentions that “the RDF describing a

particular resource does not need to be located all in one place; instead, it may be distributed throughout the Web.” We all know that Web sites can become temporarily or permanently unavailable. What challenges does this pose for a metadata framework that is distributed?

• Mike Wooldridge Answer:– I would answer that this is a good argument for redundancy of

metadata (and data, for that matter) across the Web. The fact that information can be distributed using RDF means that there can be more copies of it, which can help ensure availability.

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• Mike Wooldridge on “RDF Primer”– What happens if different people create

metadata for the same external resource using RDF, but use conflicting models, or describe the resource in markedly different ways?

• Mike Wooldridge Answer:– Since RDF information uses namespaces, we can at

least distinguish between two conflicting instances of metadata. Perhaps standards built on top of RDF can help solve the problem of conflicts?

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• Mike Wooldridge on “RDF Primer”– One problem with metadata on the Web is that there

isn’t enough of it. But another problem is the fact that metadata standards are abused by keyword spammers and the like. Does RDF speak to this problem?

• Mike Wooldridge Answer:– RDF makes possible a richer metadata framework that can be

applied consistently to Web pages. Perhaps this better framework can help people assess whether the creators of metadata are legitimate and can be trusted. Maybe a code could be added in the “Publisher” part of the Dublin Core that could be verified by a third party, similar to how certificate authorities such as VeriSign operate.

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Lecture Contents




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Homework (!)

• Read – Faceted Classification (Gower)

• Scott Fisher– Faceted Classification: Input to the Systems (Vickery)

• Morgan Ames– Faceted Classification as a Basis for Knowledge Organization in a

Digital Environment: the Bliss Bibliographic Classification as a Model for Vocabulary Management and the Creation of Multidimensional Knowledge Structures (Broughton)

• Paul Poling• Steve Chan

– Jakob Nielsen on using card-sorting techniques (Nielsen)• Christine Jones

– Chapter F: Flow of Work in the Construction of Indexing Languages and Thesauri (Soergel)

• Lilia Manguy– Faceted Metadata for Image Search and Browsing (Yee, Swearington,

Li, Hearst)• Carrie Burgener

2004.11.04 - SLIDE 1IS 202 - FALL 2004 Lecture 20: Semantic Web and RDF Prof. Ray Larson & Prof....

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