lecture course service-oriented computing 10:...

Fuyuki Ishikawa （石川冬樹）[email protected]

Lecture CourseService-Oriented Computing

10: Related Topics (4): Semantic Web2012/06/20

1 Introduction

2 Basics: Distributed Objects

3 Basics: XML

4 Web Services: Foundations

5 Web Services: Composition

6 Web Services: Implementation

7 Related Topics (1): Reliability

SOC'12 @ Sokendai 2Fuyuki Ishikawa

Course Plan

8 Related Topics (2): Security

9 Related Topics (3): Engineering

10 Related Topics (4): Semantic Web

11 Cloud Computing (1): Overview

12 Cloud Computing (2): Experience

13 Discussion and Summary

14 Students’ Presentation


Course Plan

Semantic WebVisionRDFRDFSOWLOther Specifications

Semantic Web ServicesVisionOWL-STechniques

4

TOC

SOC'12 @ Sokendai Fuyuki Ishikawa

On the Web, I see everyday my bank statements, photographs, and calendarQuestion

Can I See my photos in my calendar to see what I was doing when I took them?Can I see bank statement lines in my calendar?

Why not?Because we don't have a web of dataBecause data is controlled by applications, and each application keeps it to itself[W3C Semantic Web Activity: http://www.w3.org/2001/sw/]

5

Semantic Web: Vision


The current WebOnly exchanges design information of data, for humans, provided by each Web applicationLack explicit representation of data or their relationships, provided by different Web applications

The main goals of the Semantic WebAllows data to be surfaced in the form of real dataAllows people to write (or generate) files which explain, to a machine, the relationship between different sets of data[from the FAQ of the W3C Semantic Web Activity: http://www.w3.org/2001/sw/]

6

Semantic Web: Vision


7

Semantic Web and Web ServicesCurrent Web Semantic Web

Web Service

Semantic Web Service

<table><tr><td>2008/06/23</td>…

<date>2008/06/23

</date>…

… 2008/06/23Is-a date (is an instance of the concept date)• date has-a year• birthday is-a date• date is the same concept as the one called 日にち in the application A

Machines can directly use services provided by machines

Machines can understand and make use of data relationships


Ontology: a formal explicit specification of a shared conceptualization of a domain of interest

Formal: machine-processibleExplicit: including common sense for humansShared: agreed by people or their machines in a communityConceptuality: representing concepts and their relations in terms of symbols, covering as many situations as possibleDomain-specificity: focusing on details in a domain, modularizing and separating domains of interest

8

Ontology


Semantic Web ServicesUsuallynot "Semantic Web" Servicesbut Semantic "Web Services"

9

Note




10

TOC


RDF: Resource Description Framework(W3C Recommendation in 1999)

Originally intended for representing metadata about Web resources (e.g., title, author, modification date)Provides a more general framework to describe relationships called RDF triples: Subject, Predicate, and ObjectUses URI to identify subjects, predicates and objects (including literal values)Provides a graph model as well as XML syntaxes including many abbreviated notations

11

RDF: Overview


12

RDF: Graph Data Model

(Cited from the RDF specification Primer)SOC'12 @ Sokendai Fuyuki Ishikawa

13

RDF: XML Syntax

<?xml version="1.0"?><rdf:RDF

xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:exterms="http://www.example.org/terms/">

<rdf:Description rdf:about="http://www.example.org/index.html"><exterms:creation-date>August 16, 1999</exterms:creation-date><dc:language>en</dc:language><dc:creator rdf:resource="http://www.example.org/staffid/85740"/>

</rdf:Description></rdf:RDF>


14

RDF: Into Semantic Network


15

RDF: Flexible Notations

<rdf:RDF …><rdf:Description rdf:about="http://www.example.org/index.html">…<dc:creator rdf:resource="http://www.example.org/staffid/85740"/>


<rdf:RDF …><rdf:Description rdf:about=" http://www.example.org/staffid/85740 "><dc:city>Bedford</dc:city>…



16

RDF: Flexible Notations

<rdf:RDF …><rdf:Description rdf:about="http://www.example.org/index.html">…<dc:creator rdf:resource="http://www.example.org/staffid/85740"/><rdf:Description><dc:city>Bedford</dc:city>…

</rdf:Description></rdf:Description>

</rdf:RDF>

Can be included inline(the Description element can be omitted)


RDF defines a property type to describe a class that a resource belongs to

Also provides an abbreviated notation

(For literals, types can be associated, e.g., by referring to XML Schema types)

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RDF: Class Description

<rdf:Description rdf:ID=“carA"><rdf:type rdf:resource=“http://.../MotorVehicle"/>

</rdf:Description>

<ex:MotorVehicle rdf:ID=“carA”/>


RSS 1.0 (RDF Site Summary)

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RDF: Application (RSS 1.0)

<rdf:RDF …>…<rss:item

rdf:about="http://www.w3.org/News/2002#item164"><rss:title>User Agent Accessibility Guidelines Become

a W3C Proposed Recommendation </rss:title><rss:description> 17 October 2002: W3C is pleased to

announce the …</rss:description><rss:link>http://www.w3.org/News/2002#item164</rss:link><rss:date>2002-10-17</rss::date>

</rss:item> </rdf:RDF>


FOAF (Friend of a Friend)

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RDF: Application (FOAF)

<rdf:RDF ...><foaf:Person><foaf:name>Fuyuki Ishikawa</foaf:name><foaf:mbox rdf:resource="mailto:[email protected]"/><foaf:msnChatID>…</foaf:msnCharID><foaf:knows><Person> … </Person>…

</foaf:knows></foaf:Person>

</rdf:RDF>


CC/PP: Composite Capabilities/Preferences Profile

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RDF: Application (CC/PP)

<ccpp:component><rdf:Description rdf:ID="UserPreferences"><rdf:type rdf:resource="http://.../v1_0#UserPreferences"/><ex:AudioOutput>Yes</ex:AudioOutput><ex:Graphics>No</ex:Graphics><ex:Languages><rdf:Seq><rdf:li>en-cockney</rdf:li><rdf:li>en</rdf:li>

</rdf:Seq></ex:Languages>

</rdf:Description></ccpp:component>




21

TOC


RDFS: RDF SchemaProvides a basic vocabulary to describe (define) RDF vocabularies, or ontologiesIncluded as part of the RDF specificationPrimarily handles

Inheritances of resources, i.e., subclasses and sub-propertiesDomains and ranges or properties

22

RDFS: Overview


RDFS: Class definitionMotorVehicle is a ClassVan is a subclass of MotorVehicle

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RDFS: Examples

<rdf:Description rdf:ID="MotorVehicle"><rdf:type rdf:resource="http://.../rdf-schema#Class"/>

</rdf:Description>

<rdf:Description rdf:ID="Van"><rdf:type rdf:resource="http://.../rdf-schema#Class"/><rdfs:subClassOf rdf:resource=“#MotorVehicle"/>

</rdf:Description>


RDFS: Property definitionregisteredTo is a PropertyThe domain of registeredTo is MotorVehicleThe range of registeredTo is Person

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RDFS: Examples

<rdf:Description rdf:ID=“registeredTo"><rdf:type rdf:resource="http://.../rdf-schema#Property"/><rdfs:domain rdf:resource="#MotorVehicle"/><rdfs:range rdf:resource="#Person"/>

</rdf:Description>


RDFS: Property definitionhasDriver is a PropertyThe domain of hasDriver is MotorVehiclehasPrimaryDriver is a sub-property of hasDriver(inheriting the domain)

25

RDFS: Examples

<rdf:Description rdf:ID=“hasDriver"><rdf:type rdf:resource="http://.../rdf-schema#Property"/><rdfs:domain rdf:resource="#MotorVehicle"/>

</rdf:Description>

<rdf:Description rdf:ID=“hasPrimaryDriver"><rdf:type rdf:resource="http://.../rdf-schema#Property"/>

<rdfs:subPropertyOf rdf:resource="#hasDriver"/> </rdf:Description>




26

TOC


OWL: Web Ontology LanguageProvides a rich vocabulary to describe (define) RDF vocabularies, or ontologies, in order to support useful reasoning tasks

Three subclassesOWL-Lite: simple and easy to implement, only with a classification hierarchy and simple constraintsOWL-DL: expressive but computable and decidable with certain restrictionsOWL-Full: fully expressive with a syntactic freedom

27

OWL: Overview


28

OWL: Definition and Reasoning Examples

<owl:Class rdf:ID="WhiteWine"><owl:intersectionOf rdf:parseType="Collection"><owl:Class rdf:about="#Wine" /><owl:Restriction><owl:onProperty rdf:resource="#hasColor" /><owl:hasValue rdf:resource="#White" />

</owl:Restriction></owl:intersectionOf>

</owl:Class>

<BaseballPlayer rdf:ID="イチロー"><owl:sameAs rdf:resource="http://mlb.com/.../Ichiro" />

</BaseballPlayer>

WineABC type WhiteWine⇒ WineABC hasColor White


29


<owl:Class rdf:ID="Wine"><rdfs:subClassOf rdf:resource="&food;PotableLiquid"/><rdfs:subClassOf><owl:Restriction><owl:onProperty rdf:resource="#madeFromGrape"/><owl:minCardinality >1</owl:minCardinality></owl:Restriction>

</rdfs:subClassOf><rdfs:subClassOf><owl:Restriction><owl:onProperty rdf:resource="#hasMaker" /><owl:allValuesFrom rdf:resource="#Winery" />

</owl:Restriction></rdfs:subClassOf>

</owl:Class>

A subclass of Class, which includes resources that has at least one grape as ingredient

A subclass of Class, which includes resources that has a winery as its maker

WineABC type Wine∧ WineABC hasMaker George⇒ George type Winery


30


<owl:ObjectProperty rdf:ID="locatedIn"><rdf:type rdf:resource="&owl;TransitiveProperty" /><rdfs:domain rdf:resource="&owl;Thing" /><rdfs:range rdf:resource="#Region" /> </owl:ObjectProperty>

<Region rdf:ID="SantaCruzMountainsRegion"><locatedIn rdf:resource="#CaliforniaRegion" />

</Region><Region rdf:ID="CaliforniaRegion"><locatedIn rdf:resource="#USRegion" />

</Region>

⇒ SantaCruzMountainsRegion locatedIn USRegion


OWL-Lite vocabulariesEquality and inequality

equivalentClass (in a sense of including the same set of individuals, not equality of the concept)equivalentPropertysameAs, differentFrom, AllDifferent(about individuals)

Property characteristicsinverseOfTransitiveProperty, SymmetricProperty, FuntionalProperty, InverseFunctionalProperty

31

OWL: OWL-Lite


OWL-Lite vocabulariesProperty restrictions

allValuesFrom, someValuesFromProperty cardinarity restriction

minCardinarity, maxCardinarity(0 or 1 in OWL-Lite)

Class intersectionintersectionOf

32

OWL: OWL-Lite


OWL-DL: additional vocabularies (to OWL-Lite)Class relationships

oneOf, unionOf, complementOf, disjointWithProperty restriction

hasValue, DataRangeOWL-DL: removed restrictions (from OWL-Lite)

The object can only be a class name or a restriction in type, equivalentClass, subClassOf, and intersectionOfThe object can be any non negative integer in minCardinarity, maxCardinarity…

33

OWL: OWL-DL


OWL-Full: removed restrictions (from OWL-DL)Distinction must be made between each pair of classes, datatypes, datatype properties, object properties, individuals, data values and the built-in vocabulary, etc.

e.g., OWL-Full allows to say classA is sameAs classBe.g., OWL-Full allows to say classA has type (is an instance of) classBe.g., OWL-Full allows to say hasWeightInKg is transitive (though a subject of the transitiveproperty should be an object property, not a datatype property)

34

OWL: OWL-Full


OWL-Full: removed restrictions (from OWL-DL)No cardinality constraints should not be given for transitive properties, either directly or indirectly (given for super-properties of inverse properties)

e.g., OWL-Full allows to say a property is both transitive and functional, which is impossible

All statements (called axioms in OWL) must be well-formed, with no missing or extra components, leading to tree-like structure

e.g., OWL-Full allows for lack of definition of referenced resources

35

OWL: OWL-Full


What is DL in OWL-DL?DL: Description Logic

Each of OWL-Lite and OWL-DL has a corresponding dialect of Description Logic(not in the scope of this lecture)Well-understood computational properties and decidability

36

Note




37

TOC



Semantic Web: Layer Cake

Query language to query data from RDF documents

e.g., SPARQL (W3C)

39

Other specifications: SPARQL

• PersonA hasName Bob• PersonA hasMbox [email protected]• PersonB hasName Alice• PersonB hasMbox [email protected]

DataData

SELECT ?name ?mboxWHERE{ ?x hasName ?name .

?x hasMbox ?mbox }

QueryQuery

?name ?mboxBob [email protected] [email protected]

ResultResult


Rule language to formalize and process semantics

e.g., SWRL (Semantic Web Rule Language, W3C)

40

Other specifications: SWRL

hasParent(?x1,?x2) ∧ hasBrother(?x2,?x3)⇒ hasUncle(?x1,?x3)

Student(?x1) ⇒ Person(?x1)

The same as Student isSubclassOf Person using the OWL vocaburary


Activities to increase actual instances of data described with semantic web techniques (in RDF)

http://linkeddata.org/Wikipedia:http://dbpedia.org/National Diet Library japan: http://id.ndl.go.jp/auth/ndlsh/US Government: http://www.data.gov/communities/semantic/index

…


Linked Data



42

TOC


Semantic Web Services: Motivating tasksAutomatic discovery

e.g., find service providers that sell airline tickets for Tokyo-Paris and accept payment by a JCB card

Automatic invocatione.g., invoke service providers found at runtime by understanding what input is necessary to invoke the service, and what information will be returned

Automatic selection, composition and interoperatione.g., select service providers to compose a service that makes all the travel arrangements

43

Semantic Web Services: Vision


Related Proposals (to W3C all in 2005)OWL-S: OWL ontology for Services

Based on DARPA activities on agents and ontologies (since 2001)

WSMO: Web Service modeling OntologyProposed to deal with limitations in OWL-S

WSDL-S: Web Service SemanticsDefines a way to include references to semantic descriptions in WSDL documents (not about how semantics are described)

44

Semantic Web Services: Vision




45

TOC


OWL-S: OWL Ontology for ServicesDefines vocabularies to describe servicesEspecially models IOPEs of services

InputsOutputsPreconditionsEffects

Formally called DAML-SBased on DAML + OIL, the ancestor of OWL

DAML: DARPA Agent Markup Language

46

OWL-S: Overview


47

Semantic Web and Web ServicesCurrent Web Semantic Web

Web Service

Semantic Web Service

<table><tr><td>2008/06/23</td>…

<date>2008/06/23

</date>…

… 2008/06/23Is-a date (is an instance of the concept date)• date has-a year• birthday is-a date• date is the same concept as the one called 日にち in the application A

Machines can directly use services provided by machines

Machines can understand and make use of data relationships



OWL-S: Upper Ontology

(Cited from the OWL-S specification)


OWL-S: Service Profile



OWL-S: Process Model



OWL-S: Service Grounding




52

TOC


One aspect of discovery: how to match inputs/outputs requested with inputs/outputs accepted (provided)?

Exact: the accepted concept (class) for input or output is equivalent to the requested onePlugin: the accepted concept for input or output is sub-concept of the requested oneSubsume: the accepted concept for input or output is super-concept of the requested oneIntersection: intersection of the accepted concept for input or output and the requested one is not empty

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Typical Techniques: Discovery


One aspect of composition: how to compose a service, given a goal, by integrating existing services?

Automated service composition is often thought as aplanning problem in AIVarious planning tools (and involved logical formalisms) have been used (e.g., SHOP2)For simplicity, only I/O matching is sometimes considered(e.g., describing I/O graphs and finding a path from a certain input to a certain output)

54

Typical Techniques: Composition


One aspect of mediation: how to mediate interoperation by inserting required translations?

Data mediation (syntax, encoding, etc.)e.g., From XML documents to RDF documents

Ontology mediatione.g., mapping a terminology to another that refers to the same concept

Protocol Mediatione.g., inserting acknowledgements

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Typical Techniques: Mediation


June 22Cloud Computing (1): Overview

56Fuyuki Ishikawa

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lecture course service-oriented computing 10:...

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