semantic web portal and tools ching-long yeh 葉慶隆 department of computer science and...

Semantic Web Portal and Tools

Ching-Long Yeh 葉慶隆Department of Computer Science and Engineering

Tatung University

[email protected]

http://www.cse.ttu.edu.tw/chingyeh

Semantic Web Portal 2

OutlineOutline

• A brief description to the Semantic Web Portal• Architectural basis of the Semantic Web• KA2: an ontology-based web portal• An architecture of RDF triple data store • Conclusions


Introduction to Semantic WebIntroduction to Semantic Web

• Facilities to put machine-understandable data on the Web are becoming a high priority for many communities.

• The Web can reach its full potential only if it becomes a place where data can be shared and processed by automated tools as well as by people.

• For the Web to scale, tomorrow's programs must be able to share and process data even when these programs have been designed totally independently.


Introduction to Semantic WebIntroduction to Semantic Web

• The Semantic Web is a vision:

• See “W3C Semantic Web Activity,” by Marja-Riitta Koivunen, for more descriptions.

the idea of having data on the web defined and linked in a way that it can be used by machines not just for display purposes, but for automation, integration and reuse of data across various applications

http://www.w3.org/Talks/2001/1102-semweb-fin/Overview.html


The Semantic Web Layered ArchitectureThe Semantic Web Layered Architecture

(http://www.w3.org/2001/Talks/0228-tbl/slide5-0.html)

Tim Berners-Lee:“Axioms, Architecture and Aspirations”W3C all-working group plenary Meeting28 February 2001

URI Unicode

XML Namespaces

XML Schema

Sig

RDF M&S

RDF Schema

Ontology

Rules

Logic

Proof

Trust

The Big Picture of SW


Web PortalsWeb Portals

• A web portal is a web site that provides information content on a common topic.– General portals, e.g., Yahoo, Excite, Netscape, Lycos,

CNET, MSN, and AOL.com– Specialized portal e.g., gardeners.com, semanticweb.org

• Making valuable information to be found– directory service, – search facility– news, e-mail, – community forum


Ontology-Based Web PortalsOntology-Based Web Portals

• Ontology represents– common knowledge and interests sharing within their

community

• Tasks that ontology can be used to support a portal– Accessing a portal

• Conceptual search and navigation

• Inference capabilities

– Providing information• Methods and tools accounting for the diversity of information

sources


Introduction to XML-Based OntologyIntroduction to XML-Based Ontology

URI Unicode

XML Namespaces

XML Schema

Sig

RDF M&S

RDF Schema

Ontology

Rules

Logic

Proof

Trust


What is XML?What is XML?

• Extensible Markup Language• A Syntax for Documents • A Meta-Markup Language• A Structural and Semantic Language, not a

Formatting Language• Not just for Web pages


Namespace BindingsNamespace Bindings

• Prefixes are bound to namespace URIs by attaching an

xmlns:prefix attribute to the prefixed element or one of its

ancestors, prefix:name1 ,..., prefix:namen

• The value of the xmlns:prefix attribute is a URI, which

may or (unlike for DTDs!) may not point to a description

of the namespace’s syntax

• An element can use bindings for multiple name-spaces

via attributes xmlns:prefix1 ,..., xmlns:prefixm


XML Document Instance and DTDXML Document Instance and DTD

<mail:address xmlns:mail="http://www.deutschepost.de/" xmlns:tele="http://www.telekom.de/"> <mail:name>Xaver M. Linde</mail:name> <mail:street>Wikingerufer 7</mail:street> <mail:town>10555 Berlin</mail:town> <mail:bill>12.50</mail:bill> <tele:phone>030/1234567</tele:phone> <tele:phone>030/1234568</tele:phone> <tele:fax>030/1234569</tele:fax> <tele:bill>76.20</tele:bill></ mail:address>

<!ELEMENT address (name, street, town, bill, phone+, fax+, bill)><!ELEMENT name (#PCDATA)><!ELEMENT street (#PCDATA)><!ELEMENT town (#PCDATA)><!ELEMENT bill (#PCDATA)><!ELEMENT phone (#PCDATA)><!ELEMENT fax (#PCDATA)><!ELEMENT ARTIST (#PCDATA)>


XML SchemaXML Schema

• An XML syntax that's an alternative and/or supplement to DTDs

• Data typing of element and attribute content

RDF M&SRDF M&S• RDF (Resource Description Framework)

– Beyond Machine readable to Machine understandable

• RDF consists of two parts– RDF Model (a set of triples)– RDF Syntax (different XML serialization syntaxes)

• RDF Schema for definition of Vocabularies (simple Ontologies) for RDF (and in RDF)


RDF Data ModelRDF Data Model• Resources

– A resource is a thing you talk about (can reference)– Resources have URI’s– RDF definitions are themselves Resources (linkage, see

requirement 1)

• Properties – slots, define relationships to other resources or atomic values

• Statements– “Resource has Property with Value”– (Values can be resources or atomic XML data)

• Similar to Frame Systems


A Simple ExampleA Simple Example• Statement

– “Ora Lassila is the creator of the resource http://www.w3.org/Home/Lassila”

• Structure– Resource (subject) http://www.w3.org/Home/Lassila– Property (predicate) http://www.schema.org/#Creator– Value (object) "Ora Lassila”

• Directed graph

http://www.w3.org/Home/Lassilas:Creator

Ora Lassila


EmailName

s:Creator

http://www.w3.org/Home/Lassila

Another ExampleAnother Example

• To add properties to Creator, point through an intermediate Resource.

Person://fi/654645635

Ora Lassila [email protected]


Example:Example: Bag Bag

• The students incourse 6.001 are Amy, Tim,John, Mary,and Sue

Rdf:Bag

/Students/Amy

/Students/Tim

/Students/John

/Students/Mary

/Students/Sue

bagid1

/courses/6.001

students

rdf:type

rdf:_1

rdf:_2

rdf:_3

rdf:_4

rdf:_5


rdf:_1

rdf:_2

rdf:_3

rdf:typesource

ftp.eu.net

ftp.cs.purdue.edu

ftp.x.org

Example:Example: Alternative Alternative

• The source code for X11 may be found at ftp.x.org, ftp.cs.purdue.edu, or ftp.eu.net

altid

rdf:Althttp://x.org/package/X11


RDF Syntax IRDF Syntax I

• Data model does not enforce particular syntax• Specification suggests many different syntaxes

based on XML• General form:

<rdf:RDF> <rdf:Description about="http://www.w3.org/Home/Lassila"> <s:Creator>Ora Lassila</s:Creator> <s:createdWith rdf:resource=“http://www.w3c.org/amaya”/> </rdf:Description></rdf:RDF>

Starts an RDF-Description

Properties

Subject (OID)

Literal

Resource (possibly another RDF-description)


Resulting GraphResulting Graph

<rdf:RDF> <rdf:Description about="http://www.w3.org/Home/Lassila"> <s:Creator>Ora Lassila</s:Creator> <s:createdWith rdf:resource=“http://www.w3c.org/amaya”/> </rdf:Description></rdf:RDF>

http://www.w3c.org/amaya


Ora Lassila

s:createdWiths:Creator

RDF Syntax II: Syntactic VarietiesRDF Syntax II: Syntactic Varieties

<s:Homepage rdf:about="http://www.w3.org/Home/Lassila” s:Creator=“Ora Lassila”/>

<s:createdWith> <s:HTMLEditor rdf:about=“http://www.w3c.org/amaya”/> </s:createdWith> </s:Homepage>

Typing InformationIn-Element Property

Property

Subject (OID)

http://www.w3c.org/amaya


Ora Lassila

s:createdWiths:Creator

HTMLEditor

s:Homepagerdf:type

rdf:type


RDF Schema (RDFS)RDF Schema (RDFS)

• RDF just defines the data model

• Need for definition of vocabularies for the data model - an

Ontology Language!

• The RDF Schema mechanism provides a basic type system for

use in RDF models.

• The RDF schema specification language is less expressive, but

much simpler to implement, than full predicate calculus languages

such as CycL and KIF.


Most Important Modeling PrimitivesMost Important Modeling Primitives

• Core Classes– Root-Class rdfs:Resource

– MetaClass rdfs:Class

– Literals rdfs:Literal

• rdfs:subclassOf-property

• Inherited from RDF: properties (slots)

• rdfs:domain & rdfs:range

• rdfs:label, rdfs:comment, etc.

• Inherited from RDF: InstanceOf (rdf:type)


DAML+OIL: an Ontology LanguageDAML+OIL: an Ontology Language

• Extension of RDF Schema• Ontology Language DAML+OIL: Result of a Joint

(European + US-American) Committee• Extension of RDF Schema

– Class Expressions (Intersection, Union, Complement)– XML Schema Datatypes– Enumerations– Property Restrictions

• Cardinality Constraints

• Value Restrictions


Example: Intersection & SynonymsExample: Intersection & Synonyms

<daml:Class rdf:ID="TallMan"> <daml:intersectionOf rdf:parseType="daml:collection">

<daml:Class rdf:about="#TallThing"/> <daml:Class rdf:about="#Man"/>

</daml:intersectionOf> </daml:Class>

<daml:Class rdf:ID="HumanBeing"><daml:sameClassAs rdf:resource="#Person"/>

</daml:Class>


Example: Disjoint & ComplementExample: Disjoint & Complement<daml:Disjoint rdf:parseType="daml:collection"><daml:Class rdf:about="#Car"/> <daml:Class rdf:about="#Person"/> <daml:Class rdf:about="#Plant"/>

</daml:Disjoint>

<daml:Class rdf:ID="Car"><rdfs:comment>no car is a person</rdfs:comment> <rdfs:subClassOf>

<daml:Class><daml:complementOf rdf:resource="#Person"/>

</daml:Class> </rdfs:subClassOf>

</daml:Class>

Disjoint not strictly necessary, since expressible via pairwise subClassOfof complementOf, as for Car and Person:


Example: Properties Example: Properties (Transitive, Inverse, subProperty, UniqueProperty, range, Datatypes)(Transitive, Inverse, subProperty, UniqueProperty, range, Datatypes)

<daml:TransitiveProperty rdf:ID="hasAncestor"/>

<daml:ObjectProperty rdf:ID="hasChild"><daml:inverseOf rdf:resource="#hasParent"/>

</daml:ObjectProperty>

<daml:UniqueProperty rdf:ID="hasMother"><rdfs:subPropertyOf rdf:resource="#hasParent"/><rdfs:range rdf:resource="#Female"/>

</daml:UniqueProperty>

<daml:DatatypeProperty rdf:ID="age"><rdf:type rdf:resource="http://www.daml.org/2001/03/daml+oil#UniqueProperty"/><rdfs:range rdf:resource="http://www.w3.org/.../XMLSchema#nonNegativeInteger"/>

</daml:DatatypeProperty>

Using User-defined DatatypesUsing User-defined Datatypes(based on XML Schema)(based on XML Schema)

<xsd:simpleType name="over17">  <xsd:restriction base="xsd:decimal"> <xsd:minInclusive value="18"/> </xsd:restriction>

</xsd:simpleType>

<daml:Class rdf:ID="Adult"><daml:intersectionOf rdf:parseType="daml:collection">

<daml:Class rdf:about="#Person"/> <daml:Restriction><daml:onProperty rdf:resource="#age"/><daml:hasClass rdf:resource="somefile#over17"/>

</daml:Restriction> </daml:intersectionOf> </daml:Class>


Instances (Individuals)Instances (Individuals)

<Person rdf:ID="Adam"> <rdfs:label>Adam</rdfs:label> <rdfs:comment>Adam is a person.</rdfs:comment> <age><xsd:integer rdf:value="13"/></age> <shoesize>

<xsd:decimal rdf:value="9.5"/></shoesize>

</Person>

<daml:Class rdf:ID="Person"> . . .</daml:Class>


Web ServicesWeb Services

Serviceregistry

Servicerequester

Serviceprovider

FindWSDL, UDDI

PublishWSDL, UDDI

Bind

Servicedescriptions

Servicedescriptions

Services


DAML-SDAML-S

• Users and software agents should be able to discover, invoke, compose, and monitor Web resources offering particular services and having particular properties.

• As part of the DARPA Agent Markup Language program, we have begun to develop an ontology of services, called DAML-S.


Top Level of the Service OntologyTop Level of the Service Ontology

Service

Resource

ServiceGrounding

ServiceProfile

ServiceModel

provides presents

supports described by

(what it does)

(how it works)(how to access it)


Process Modeling OntologyProcess Modeling Ontology


Concept of ebXML Business Concept of ebXML Business Process Specification SchemaProcess Specification Schema


Business Process Specification in XML

KA2 KA2 An Ontology-Based Community Web PortalAn Ontology-Based Community Web Portal


KA2KA2

• Knowledge Annotation Initiative of the Knowledge Acquisition Community

• The basic scenario– WWW documents of the KS community were annotated

according to the schema of an ontology.– The annotations enable intelligent access to these

documents and infer implicit knowledge from explicitly stated facts and rules from the ontology.

The KA2 OntologyThe KA2 Ontology

Class hierarchyPerson Employee Academic-Staff Lecturer Researcher Administrative-Staff Secretary Technical-Staff Student Phd-Student

RelationsAddress, Affiliation, Cooperates-With, Editor-Of,Email, First-Name, Has-Publication, Head-Of-Group, Head-Of-Project, Last-Name, Member-Of-Organization, Member-Of-Program-Committee, Member-Of-Research-Group, Middle-Initial, Organizer-Of-Chair-Of, Person-Name, Photo, Research-Interest, Secretary-Of, Studies-At, Supervises, Supervisor, Works-At-Project

Person-ontologyClass hierarchyOn-Line-PublicationPublication Article Article-In-Book Conference-Paper Journal-Article Technical-Report Workshop-Paper Book Journal IEEE-Expert IJHCS Special-Issue

RelationsAbstract, Book-Editor, Conference-Proceedings-Title, Contains-Article-In-Book, Contains-Article-In-Journal, Describes-Project, First-Page, Has-Author, Has-Publisher, In-Book, In-Conference, In-Journal, In-Organization,In-Workshop, Journal-Editor, Journal-Number, Journal-Publisher, Journal-Year, Last-Page, On-Line-Version, …

Publication-ontology


Accessing the Community Web PortalAccessing the Community Web Portal

• Query capability– In F-Logic mechanism

• Navigating capability– As the easy-to-use front-end of the query mechanism


Query CapabilitiesQuery CapabilitiesFor all publications of the researcher “Steffen Staab”.

FORALL Pub <-EXISTS ResID ResID:Researcher[NAME->> Steffen "Staab"; PUBLICATION ->> Pub].

Two researchers cooperate, if a Researcher X works at a Project Proj and if a Researcher Y works at the same Project Proj and X is another person than YFORALL X; Y; Proj X:Researcher[COOPERATESWITH ->> Y:Researcher] <- X:Researcher[WORKSATPROJECT->>Proj:Project] AND Y:Researcher[WORKSATPROJECT->>Proj:Project] AND NOT equal(X; Y ):

Which researchers are cooperating with other r?

FORALL ResID1, ResID2 <- ResID1:Researcher[COOPERATESWITH ->> ResID2].


Navigating and Querying the PortalNavigating and Querying the Portal

• Query the portal using F-Logic is too inconvenient.• Navigating and querying the web

– A hypertext link may contain a query dynamically evaluated when clicking on the link (See P. 45)

– Query generated by using the hyperbolic view interface (See P. 46)

– Queries may be personalized and for the different users and available for the user in a selection list.

– An expert mode: Querying the portal by typing an F-Logic statement


Providing InformationProviding Information

• Integrating various syntactic and semantic formats based on the common ontology

• Three different modes of information provision are supported– Metadata-based information– Wrapper-based information– Fact-based information


Metadata

Metadata-based InformationMetadata-based Information

Information source

Annotation tool

In RDF, XML

(OntoPad Annotea, …)


Wrapper-based InformationWrapper-based Information

• Annotating information sources by hand is time-consuming.

Semi-structuredInformation sources(e.g., HTML)

StructuredInformation sources(e.g., RDB)

Wrapperprogram

Metadata

(Onto Wrapper)


Fact-Based InformationFact-Based Information

Fact Editor

New factscreate

add,modify,delete

Knowledgewarehouse (Ontoedit, OilED,

Protégé 2000)


Development of Web PortalsDevelopment of Web Portals


The System ArchitectureThe System Architecture

Development of an Ontology-Based Portal for Digital Archive Services


IntroductionIntroduction

Content providers

User User User User

Portal

Goal


Technical ArchitectureTechnical Architecture

Web server

Web server

Web server

Web server

Content providers

User User User User

OntologyKnowledgewarehouse

Portal

Annotator Wrapper

Discovery Use Tailoring Social

Inference engine

Content provisioncomponent

Core component

Service component


Ontology Construction and Inference EngineOntology Construction and Inference Engine

• In the portal, the semantic content and the control are separated. – The ontology and the knowledge warehouse are the schema

and facts of the semantic content. – The inference engine controls the interpretation of rules

specified in the service programs.


Ontology ConstructionOntology Construction

• We first of all adapt for our purpose from the ontology developed in the KA2 project, building an ontology-based portal for the knowledge acquisition community.

• The KA2 ontology consists of – organization,

– person,

– publications,

– projects,

– events,

– research topics and

– products


Ontology ConstructionOntology Construction

• To integrate the ontology with metadata from the content providers, we add metadata schema generally used in the field of digital libraries, DC and DC-Q, using the syntax of the ontology language DAML.


Inference EngineInference Engine

• flex – based on the logic programming system, Prolog, – supporting frame representation, forward and backward

chaining inferences– local GUI, – connecting with web server, and– TCP/IP and agent libraries.


Inference EngineInference Engine

• To make use of flex,1. Representing the ontology schema using the frame

representation of flex;

2. Representing RDF instance as the flex instances;

3. Implementing each service program using backward and forward chaining rules


RDFS in RDFS in flex flex FrameFrame<rdfs:Class rdf:ID="Journal"> <rdfs:subClassOf rdf:resource="#Publication"/> <daml:restrictedBy> <daml:Restriction> <daml:onProperty rdf:resource="#editor"/> <daml:toClass rdf:resource="#Person"/> </daml:Restriction> </daml:restrictedBy> <daml:restrictedBy> <daml:Restriction> <daml:onProperty rdf:resource="#publisher"/> <daml:toClass rdf:resource="#Organization"/> </daml:Restriction> </daml:restrictedBy> <daml:restrictedBy> <daml:Restriction> <daml:onProperty rdf:resource="#number"/> <daml:toClass rdf:resource="#Number"/> </daml:Restriction> </daml:restrictedBy> <daml:restrictedBy> <daml:Restriction> <daml:onProperty rdf:resource="#volume"/> <daml:toClass rdf:resource="#Number"/> </daml:Restriction> </daml:restrictedBy></rdfs:Class>

frame ‘Journal’ is a ‘Publication’; default editor is a ‘Person’ and default publisher is an ‘Organization’ and default number is a ‘Number’ and default number is a ‘Number’.


RDF Instances in RDF Instances in flexflex

<Person rdf:ID='Peter'> <shoesize>9.5</shoesize> <age>46</age> <shirtsize>15</shirtsize></Person>

instance 'Peter' is a 'Person'; shoesize is 9.5 and age is 46 and shirtsize is 15.


Ontology(RDFS, DAML)

Knowledgewarehouse

(RDF)

Protege-2000

Translator(rdfToFlex)

Facts-in-kslrepository

Annotator

Schema-in-kslrepository

Translator(rdfsToFlex)

User

Conceptualsearch

Semanticnavigation

flex inference engine

Semantic Web Tools


AnnotationAnnotation

• " Annotation is necessary to add semantic content to your website."

• Annotation and authoring tools:http://annotation.semanticweb.org/tools


Annotation and Authoring ToolsAnnotation and Authoring ToolsOntoMat-Annotizer

• What is OntoMat-Annotizer ? – A user-friendly interactive webpage annotation tool– It supports the user with the task of creating and maintaining

ontology-based DAML+OIL markups i.e. creating of DAML-instances, attributes and relationships.

– It includes an ontology browser for the exploration of the ontology and instances and a HTML browser that will display the annotated parts of the text.

http://www.daml.org/

OntoMat-Annotizer


OntoMat-Annotizer 使用心得

• 此工具軟體對於要將網頁直接作標記和註記很方便，允許你匯入設計好的資料格式，根據匯入的 ontology加入想要加註的內容。

• 此工具在中文碼的使用上有些問題，當我們將網頁所需要的資訊做好標記之後，可以選擇將這份檔案存成 HTML文件，其內容將存於HTML的 <Head></Head>中，但是中文的值在存檔之後會變成亂碼。


Other Annotation Authoring ToolsOther Annotation Authoring Tools

• OntoAnnotate: http://www.ontoprise.com/

• The SHOE Knowledge Annotator: http://www.cs.umd.edu/projects/plus/SHOE/KnowledgeAnnotator.html

• Annotea Projecthttp://www.w3.org/2001/Annotea/

• Annozilla (Annotea on Mozilla)http://annozilla.mozdev.org/

• COHSE Softwarehttp://cohse.semanticweb.org/software.html

• SMORE: Semantic Markup, Ontology and RDF Editor http://www.mindswap.org/~aditkal/editor.shtml

• etc.


Ontology EditorOntology EditorProtégéProtégé

• Protégé allows domain experts to build knowledge-based systems by creating and modifying reusable ontologies and problem-solving methods.

• Protégé-2000 now has support for editing Resource Description Framework schema and instance data knowledge-bases.


Protégé-2000使用心得

• 這一套軟體對於 RDF(S)的處理很方便，但是對於daml+oil的文件匯入有問題，若是單純想處理 RDF(S)文件，這套工具可以很容易的將概念和關聯性建立起來，根據這項概念和關聯建立 Instance，只要將數值對應的屬性中，就可以產生 RDF。

• 但是對於 daml+oil的處理上會發生問題，所以如果想處理 daml+oil的資料，我們建議使用 ontoedit。


Other Ontology Editing ToolsOther Ontology Editing Tools

• OilEdhttp://oiled.man.ac.uk/

• OntoEdithttp://www.ontoprise.de/home


Inference Engines for the Semantic WebInference Engines for the Semantic Web

• Higher Order Logic Based Inference Engines• Full First Order Logic Based Inference Engines• Description Logic• Datalog and Logic Programming• Problem Solving Methods


XSB and the Semantic Web

• XSB is a Logic Programming and Deductive Database system for Unix and Windows.

• Why is XSB interesting for the Semantic Web? – The Semantic Web need ways to specify declaratively how

to process data on the Web. – XSB offers such a way: XSB is an efficient rule engine,

freely available, open-source, and already used in a lot of different projects, which uses rules to process data.

• XSB Resources– http://xsb.sourceforge.net

• RDF Parsers


RDF ParserRDF Parser

W3C Online RDF parserW3C Online RDF parser ：：


Ontology-Based Web PortalOntology-Based Web PortalKAON Portal

• KAON PORTAL– A simple tool for generating multi-lingual, ontology-

based Web portals.– KAON Portal is a simple tool for generating of

ontology-based Web portals. – In order to create the portal, the user needs to

create an ontology containing the information which will be presented in the Web.


Ontology-Based Web Site ManagementOntology-Based Web Site ManagementOntoWebberOntoWebber

• OntoWebber is a Web site management system, which facilitates the creation, generation and maintenance of Web sites.

• Using OntoWebber, site engineers can build site models for domain-specific Web sites.

• The site models are based on explicit ontologies including the domain ontology and four distinct site-modeling ontologies.


ConclusionsConclusions

• We separate the semantic content the function control components to build a portal for digital library environment.

• With the separation, the portal can be divided into two parts, information provision and information access, working independently to each other.

• It also facilitates the development of services at the conceptual level, for example, the conceptual search and semantic navigation of the discovery activity.

• Furthermore, we are able to develop advanced services based on such knowledge base.

• The ontology and knowledge warehouse can be extended without changing the service programs.