Lecture Lecture TelecooperationTelecooperation

D. Fensel

Leopold-Franzens-Universität Innsbruck

First Lecture:First Lecture:

Introduction:Introduction:Semantic Web & Semantic Web &

OntologyOntology

IntroductionSemantic Web and Ontology

Part I

Introduction into the subject

Ontology

Ontology...• Long history coming from Philosophy -

Aristoteles– “The metaphysical study of the nature of

being and existence”

• Pick up by the Artificial Intelligence– “a shared and common understanding

of some domain that can be communicated between people and application systems” - Gruber

What is Ontology…...

• an ontology is a formal, explicit specification of a shared conceptualization - Gruber– ‘Conceptualization’ refers to an abstract model of

phenomena in the world by having identified the relevant concepts of those phenomena.

– ‘Explicit’ means that the type of concepts used, and the constraints on their use are explicitly defined.

– ‘Formal’ refers to the fact that the ontology should be machine readable.

– ‘Shared’ reflects that ontology should capture consensual knowledge accepted by the communities

Main components of an Ontology

• Five kinds of components:– classes:

• concepts of the domain or tasks, which are usually organized in taxonomies

• in univ-ontology: student and professor are two classes

– relations: • a type of interaction between concepts of the

domain• such as: subclass-of, is-a

Main components of an Ontology (Cont.)

• Five kinds of components:– functions:

• a special case of relations in which the n-the element of the relationship is unique for the n-1 preceding elements

• Such as: Price-of-a-used-car can define the calculation of the price of the second-hand car on the car-model, manufacturing data and kilometres

– axioms• model sentences that are always true• such as: if the student attends both A and B course, then he or she

must be a second year student

– instances• to represent specific elements• such as: Student called Peter is the instance of Student class

Kinds of ontologies

• Knowledge Representation ontologies– capture the representation primitives used to

formalize knowledge in KR paradigm– such as: Frame-Ontology

• General/Common ontologies– vocabulary related to things, events, time, space,

etc.– such as: meter and inch exchange table

• Meta-ontologies– reusable across domains– such as: mereology ontology (Borst, 97)

Kinds of ontologies• Domain ontologies

– vocabularies about the concepts in a domain– such as: the theory or elementary principles governing the

domain

• Task ontologies– a systematic vocabulary of the terms used to solve problems

associated with tasks that may or may not from the same domain– such as: scheduling task ontology

• Domain-task ontology– task ontology reusable in a given domain– such as: scheduling task ontology for flight schedule

• Application ontology– necessary knowledge for modeling a particular domain– such as: ????

Ontology Applications

• Knowledge Management• Enterprise Application Integration• e-Commerce

More goes to next Lecture

URI, HTML, HTTPStaticWWW

500 million usermore than 3 billion pages

Current Web

The vision• The World Wide Web is a big and impressive success

story, both in terms– of the amount of available information and– the growth rate of human users

• It starts to penetrate most areas of our daily life and business.

• This success is based on its simplicity

the restrictivenss of HTTP and HTML allowed software developers, information providers and users to make easy access of the new media helping it to reach a critical mass

The Vision

• However this simplicity may hamper the further development of the Web

What we see currently is the very first version of the web and the next version will probably even more bigger and much powerful compared to what we have now.

URI, HTML, HTTPStaticWWW

Serious Problems in information•finding

•extracting•representing•interpreting

•and maintaining

RDF, RDF(S), OWLSemantic Web

Semantic Web

Semantic Web Technology

• Tim Berners-Lee has a vision of a Semantic Web which– has machine-understandable

semantics of information, and – millions of small specialized reasoning

services that provide support in automated task achievement based on the accessible information

The Semantic Web

• The semantic Web is essentially based on ontologies– ontologies are formal formal and

consensualconsensual specifications of conceptualizations…

– providing a shared and commonshared and common understanding of a domain that can be communicated across people and application systems

Semantic Web Technology• Ontologies glue together two essential

aspects that help to bring the web to its full potential:– ontology define a formal semantics for

information allowing information processing by a computer

– ontologies define a real-world semantics allowing to link machine processable content with meaning for humans based on consensual terminology

Semantic Web - Language tower

XML• Tags define the semantics of the data

<name>Dieter Fensel</name>• XML provides arbitrary tress (graphs) as data

structures<person>

<name>Dieter Fensel</name><phone>6084751</phone>

</person>

• XML allows the definition of application-specific tags

http://www.w3.org/XML/

XML Schema• DTDs allow to define a grammar and

meaningful tag for documents• XML schema provides similar service and add:

– XML schemas definition are itself XML documents– XML schemas provide a rich set of datatypes that

can be used to define the values of elementary tags– XML schemas provide much richer means for

defining nested tags (such as tags with subtags)– XML schemas provide the namespace mechanism to

combine XML documents with heterogeneous vocabulary

RDF• XML provides semantic information as a by-

product of defining the structure of the document

• XML prescribes a tree structure for documents and the different leaves of the tree have a well-defined tag and context the information can be understood with.

• That is, structure and semantics of documents are interwoven

RDF

• The Resource Decription Framework RDF provides a means for adding semantics to a document without making any assumptions about the structure of the document and it provides pre-defined modeling primitives for expressing semantics of data

RDF SchemaRDFs provides a simple and basic modeling

language for ontologies– concepts– properties– is-a hierarchy and– simple domain and range restrictions

be expressed in RDFsAdvanced ontology modeling need more,

however, can be realized as a layer on top of RDFs

OIL

• OIL adds a simple Description Logic to RDF Schema

• It allows to define axioms that logically describe classes, properties and their hierarchies

• OIL enables to define necessary and sufficient conditions that define class membership of instances

OIL• OIL

– Developed in the Ontoknowledge project www.ontoknowledge.org

– Core language contains consensus primitives, extensions add aditional expresiveness

– Layered architecture:• Applications are not forced to work with a language

more complex and expresive than required• Applications that can only process a low level of

complexity are able to catch the aspects of the ontology

• Applications aware of higher level of complexity can still understand a simpler ontology language

• OIL

OIL

Description Logic:

Formal Semantics & Reasoning support

Description Logic:

Formal Semantics & Reasoning support

Web languages:

XML- and RDF-based syntax

Web languages:

XML- and RDF-based syntax

Frame-based systems:

Epistemological Modeling Primitives

Frame-based systems:

Epistemological Modeling Primitives

DAML+OIL• DAML+OIL

– Semantic markup language

– Joint efford of the American and European communities

– DAML+OIL = DAM-ONT + OIL

– Designed to describe the structure of a domain in terms of classes and objects

– Supports full range of datatypes in XML

OWL• OWL

– Under development of W3C Web Ontology Working Group – DAML+OIL based– Offers:

• More accurate web searches• Intelligent agents• Knowledge management

– Abstract syntax that provides:• Higher level way of writing ontologies• Clear statement of semantics• Compound axioms resembling frames

• OWL-lite– OWL sublanguage– OWL-lite = RDFs + 0/1 cardinality– Suites well to express light weight ontologies– Limited expresiveness power

• Some fields require a full-fledged semantic web modeling language

Static

Dynamic

Bringing the computer back as a device for computation

URI, HTML, HTTP RDF, RDF(S), OWL

WWW Semantic Web

UDDI, WSDL, SOAP

Web Services

Web Service

Web Services

“Web services are a new breed of Web application. They are self-contained, self-describing, modular applications that can be published, located, and invoked across the Web. Web services perform functions, which can be anything from simple requests to complicated business processes. …Once a Web service is deployed, other applications (and other Web services) can discover and invoke the deployed service.”

IBM web service tutorial

Web Services

• Web Services connect computers and devices with each other using the Internet to exchange data and combine data in new ways.

• The key to Web Services is on-the-fly software creation through the use of loosely coupled, reusable software components.

• Software can be delivered and paid for as fluid streams of services as opposed to packaged products.

Web Services

• UDDI provides a mechanism for clients to find web services. A UDDI registry is similar to a CORBA trader, or it can be thought of as a DNS service for business applications.

• WSDL defines services as collections of network endpoints or ports. A port is defined by associating a network address with a binding; a collection of ports define a service.

• SOAP is a message layout specification that defines a uniform way of passing XML-encoded data. In also defines a way to bind to HTTP as the underlying communication protocol. SOAP is basically a technology to allow for “RPC over the web”.

Bringing the web to its full potential

Static

Dynamic UDDI, WSDL, SOAP

Web Services

URI, HTML, HTTP RDF, RDF(S), OWL

WWW Semantic Web

Intelligent Web Services

Semantic Web Service

Semantic Web Services

"Semantic differences, remain the primary roadblock to smooth application integration, one which Web Services alone won't overcome. Until someone finds a way for applications to understand each other, the effect of Web services technology will be fairly limited. When I pass customer data across [the Web] in a certain format using a Web Services interface, the receiving program has to know what that format is. You have to agree on what the business objects look like. And no one has come up with a feasible way to work that out yet -- not Oracle, and not its competitors..."

--- Oracle Chairman and CEO Larry Ellison

Semantic Web Services

• UDDI, WSDL, and SOAP are important steps into the direction of a web populated by services.

• However, they only address part of the overall stack that needs to be available in order to achieve the above vision eventually.

• There are many layer requires to achieve automatic web service discovery, selection, mediation and composition into complex services.

Semantic Web Services

• Semantic Web Services combine Semantic Web and Web Service Technology.

• Automatization of Web Service Discovery, Combination, and Invocation makes the technology scalable.

• This combination is a pre-requisite to make web service technology scalable and mature.

• This technology is a pre-requisite to enable fully open, flexible, and dynamic eWork and eCommerce a reality.

Semantic Web Services

• Mechanized support is needed in finding and comparing vendors and their offers. Machine processable semantics of information allows to mechanize these tasks.

• Mechanized support is needed in dealing with numerous and heterogeneous data formats. Ontology technology is required to define such standards better and to map between them.

• Mechanized support is needed in dealing with numerous and heterogeneous business logics. Mediation is needed to compensate these differences, allowing partners to cooperate properly.

Short Summary

• The semantic web is based on machine-processable semantics of data.

• Its backbone technology are Ontologies.

• It is based on new web languages such as XML, RDF, and OWL, and tools that make use of these languages.

• Ontologies are key enabling technology for the semantic web.

• They interweave human understanding of symbols with their machine processability.

• In a nutshell, Ontologies are formal and consensual specifications of conceptualizations that provide a shared and common understanding of a domain

Short Summary

IntroductionSemantic Web and Ontology

Part II

Lecture + Tutorial + Seminar

Lecture

When & Where

• When - Wann: – Every Thursday, from 9:15am - 10:45am

• Where - Wo:– HS A

• Who - Wer:– Univ. Prof. Dr. Dieter Fensel

• Notices:– Teaching Language: German and English

Lecture Schedule• L1: Introduction (Semantic Web and Ontologies)

• L2: Applications: KM, EAI, and eCommerce

• L3: Information Retrieval & Information Extraction

• L4: Logic (Propositional Logic and First-order logic)

• L5: Logic (First-order Logic and extensions)

• L6: XML and XML Schema

• L7: RDF and RDF Schema

• L8: Description Logic

Lecture Schedule

• L9: Frame Logic

• L10: OWL and XML/RDF relationship

• L11: Ontobroker

• L12: Ontoknowledge

• L13: Dynamic Logic & Transaction Logic

• L14: UDDI, SOAP and WSDL

• L15: BPEL4WS and WSMF

• L16: Exam feedback etc.

Attention!• Exam

– Written exam (the end of the semester)

– offer 3 exams for different time - the flexibility to choose based on your own time schedule

– Make-up exam: if you fail the exam, the coming exam is also the make-up exam for youFinal Mark = Written Exam (90%) + assignment (10%)

It is up to you…...

• Good side:– You have your freedom for attending

the lecture

• Bad side:– You must show up in the exam and

the tutorials

Tutorial

When & Where• When - Wann:

– Every Friday• 8:15 - 9:45• 10.15 - 11.45

– you will be divided into several groups

• Where - Wo:– Has to be decided (please contact Silvia Arnold

• Notices:– Teaching Language: English and German

Tutorial Schedule

• Follow the topic of the each week Lecture (look at the schedule of the Lecture

• Exercise yourself with the knowledge learned during the same week Lecture

Tutors

Tutor only speaks English:• Dr. Ying Ding• Juan Miguel Gomez• Sinuhe Arroyo• Rubén LaraTutor speaks both German and English• David Berka

Attention!• Exam

– no written exam:-)

• But ……– attendance (everyone must attend the tutorials. In total you cannot miss more

than 2 tutorials per semester)– performance in the tutorial– reports

Final Mark = attendance + performance + reports

Seminar

When & Where

• When - Wann: – Every Thursday, from 2:15am -

3:45am

• Where - Wo:– To be decided

• Notices:– Teaching Language: English and

German

Seminar Topics• Topic provided by each member of Next

Generation Web• The main focuses are:

– Ontology – Semantic Web– Web Services– Information Retrieval and Information

Extraction– Applications

Attention!• Exam

– no written exam:-)

• But ……– attendance (everyone must attend the tutorials. In total you cannot miss more

than 2 tutorials per semester)– performance in the tutorial– reports

Final Mark = attendance + performance + reports

It is up to you…...

• Good side:– You have your freedom for attending

the lecture

• Bad side:– You must show up in the exam and

the tutorials

The main HomeworkThe main HomeworkSemantic Web Semantic Web

ProjectProjectgoes through the whole goes through the whole

semestersemester

Project

Rules and Guidelines

Project

• No project done => no tutorial points• The tutorial credits based on the

followings (total 10 points)– project plan & preparation - presentation: 10%– mid-term project report: 20%– final project report: 20%– final project presentation: 30%– self evaluation report: 10%– Other presentations in the tutorials: 10%

Requirements for your project

• Topics– Try to use the Semantic Web

Technology to solve your specific problem

• Team work– form the project team (no more than 5

students)– collaboration, distribution– Team workTeam work

Project Schedule

• Phase 1– find the topic and form the team– project plan & preparation - presentation - week 3 (March 28 -

week 4 Tutorial)

• Phase 2– find the methodology to solve the problem– mid-term project report (Deadline: May 11 - week 10)

• Phase 3– final presentation (June 13 -June 27, week 13-14 Tutorial)– final project report (July 5 - week 15)– self evaluation report (July 5 - week 15)

Contact Person

• Silvia ArnoldInstitut für InformatikTechnikertraße 13A - 6020 Innsbruck

Email: Silvia.Arnold@uibk.ac.at Tel.: +43-(0)512-507-6488

Fax: +43-(0)512-507-9872Mobile: +43-(0)664-8125233

Project Requirement

• Send email with who are the project members, project name, and its topic to Silvia Arnold (no later than March 26, 2003)

• How you organize yourselves and your work is fully your own responsibility

• Submit your report to Silvia on time

Project Plan Presentation

• Around 5 PowerPoint slides• Present in the tutorial

– what is the problem– why is it interesting– how do you tackle it– highlights of your project approach

and plan– project management

Mid-term report

• Content should include the following point– project topic (what is the problem and

why it is interesting)– literature survey– potential solutions– plan for the next half-term– project management

Final project presentation

• 10 minutes to show your project work

• 10 minutes for question & answer (prepare to defense yourself)

Final Project Report

• Content should include the following points:– introduction: - what is the topic and why it is

interesting– literature survey– methodology– result or evaluation– discussion– future work– project management

Self-Evaluation Report

• Content should include the following points:– what is your role in the project– what do you learn from this project

work– how can you improve– your opinion on the lecture, tutorial

and this project

Main focus for first 2-weeks

• Form your team and find the topic• For any help, please contact our

contact person - Silvia Arnold

Readings for Lect 1

• Ontoweb deliverables– www.ontoweb.org

• W3C documents on XML, XMLs, RDF, RDFs, OWL

• More readings, please visit lecture website

Tomorrow Tutorial

• No tutorial

Lect 1- Homework• Creating your own University Ontology• helpful readings and tools

– download and play with Protégé– Ontology Development 101: A Guide to Creating

Your First Ontology– Ontoweb deliverable 1.1

• Tutorial - Week 2 will give you more detailed method.

• You will present your own work during Tutorial - Week 3