Semantic Web services

Chankyu Park08/04/2005

Agenda

• Next Generation Web• Tutorial of Ontology for SWS• Concept of SWS• OWL-S ontology• OWL-S Development Tools• Other efforts to SWS

Next Generation Web

Semantic Web Services

Semantic Web Techniques Web Services Techniques

XML

AutomatedKnowledge BasesRules (RuleML)Ontologies (OWL)Databases (SQL,XQuery, RDF)

Two interwoven aspects:Program: Web ServicesData: Semantic Web

API’s on Web(WSDL, SOAP)

First Generation

Web

SWSI Language effort,on top of Current WS Standards

StackWire Protocol Service Description

, BPML

The Semantic Web Services Initiative (SWSI) is an ad hoc initiative of academic and industrial researchers, many of which are involved in DARPA and EU funded research projects.

Tutorial of Ontology for SWS

• “An ontology is a specification of a conceptualization.”

• Ontologies consists of:- Concepts- Relations (between concepts)- Instances (specific, non generic concepts)- Axioms (knowledge using logics)

• Used for:- Defining knowledge- Communication- Knowledge reuse

- A reasoner can be used to make inferences about concepts in ontologies

Ontology Example

Shape

Circle Square

radius

conceptrelationship

subClassOf subClassOf

property

OWL

• Web Ontology Language• XML-based language for representing ontol

ogies• W3C recommendation• Build on RDF and RDFS

XML representation of OWL<!–- concept --><owl:Class rdf:ID="Shape"/><owl:Class rdf:ID="Square">

<rdfs:subClassOf rdf:resource="#Shape"/></owl:Class>

<owl:Class rdf:ID="Circle"> <rdfs:subClassOf rdf:resource="#Shape"/></owl:Class>

<!–- property --><owl:DatatypeProperty rdf:ID="radius"> <rdfs:domain rdf:resource="#Circle"/> <rdfs:range rdf:resource="&xsd;positiveInteger"/></owl:DatatypeProperty>

Semantic Web Services

• Web services were designed to be loosely coupled and inter-operable

• Traditional Web services require a huge amount of human interaction for integration of multiple applications– Because it requires an understanding of data and func

tions of the involved entities

• Semantic Web technologies add annotations to data and functions using ontologies

Semantic Web Services

• This helps create a machine processable information which can be used for automated service publication, service discovery, service composition, negotiation and execution as primary goals

• In other words:Semantic Web Services = Web Services + Semantic Web Technol

ogy

Traditional Web Service

Traditional

Web Service

Input ( name=isbn, type=int)

Input ( name=title, type=String)

Input ( name=year, type=int)

Output ( name=price, type=float)

getP

rice

Semantic Web Service

Semantic

Web Service

getP

rice

Domain Ontology

Functional Ontology

Operation = Ont#getPrice

Output (name=price, typ

e=Ont#BookPrice)

Input(name=year, type=Ont#PrintYear)

Input (name=isbn, type=Ont#ISBN)Input ( name=title, type=Ont#BookTitle)

Location=Georgia Category=Book Stores

Supply Time=2 days QoS OntologyAvailability =

0.9

OWL-S Ontology

• OWL-S is an OWL ontology to describe Web services

• Formerly called DAML_S by DAML Group• W3C Note• OWL-S leverages on OWL to

– Support capability based discovery of Web services

– Support automatic composition of Web Services– Support automatic invocation of Web services– OWL-S provides a semantic layer over Web

services standards• OWL-S relies on WSDL for Web service invocation (see

Grounding)• OWL-s Expands UDDI for Web service discovery (OWL-

S/UDDI mapping)

OWL-S Upper Ontology

• Mapping to WSDL• communication protocol (RPC, HTTP, …)• marshalling/serialization• transformation to and from XSD to OWL

• Control flow of the service•Black/Grey/Glass Box view

• Protocol Specification• Abstract Messages

•Capability specification•General features of the Service

• Quality of Service• Classification in Service

taxonomies

Service Profile (What does it do?)

• High-level characterization/summary of a service– “Black box” view: Information needed to find

and select a service– IOPE: Inputs, outputs, preconditions, effects– “Binding rules” for inputs, outputs– “Roles” involved

• Can employ logical rules• Analogous to procedure header, DB

schema

OWL-S IOPEs Example

• Input: – ItemDescription (several forms), PriceRange, AcctNam

e, Passwd, CreditCard#, Shipping-address, • Input usage rule:

– Exists(Acct) => Defined (CreditCard#, Shipping-Address)

• Precondition: – Exists(Acct) | CanCreate(Acct)

• Output: – ‘Succeed’ + Receipt | ‘Cancel’ | ‘Fail’

• Effect: – ‘Succeed’ ShippingOrderPlaced

OWL-S Upper Ontology

• Mapping to WSDL• communication protocol (RPC, HTTP, …)• marshalling/serialization• transformation to and from XSD to OWL

• Control flow of the service• Protocol Specification• Abstract Messages

•Capability specification•General features of the Service

• Quality of Service• Classification in Service

taxonomies

Service Model (How does it work?)

• Interpretable description of service provider’s behavior

• Tells service user how and when to interact (read/write messages)

• “Glass box” view• Detailed characterization of what it does• Can employ logical rules• Analogous to procedure body (but

abstract)• Used for:

– Service invocation, planning/composition, interoperation, monitoring

OWL-S Service Model

Composite Process Example

www.acmeair.com

book flight service

• customer name• flight numbers• dates• credit card no.• ... • confirmation no.

• ...

• failure notification• errror information• …

?www.acmehotel.com

book hotel service

• confirmation no.• dates• room type• credit card no.• ... • confirmation no.

• ...

• failure notification• …

?

www.acmecar.com

book car service

• customer name• location• car type• dates• credit card no.• ...

• confirmation no.• ...

• failure notification• …

?

• • • •

• • • • • • • • • •

• • • •

?

• • • • • • • • • • •

Input &Preconditions

Output &Effects

• • • •

• • • •

OWL-S Upper Ontology

• Mapping to WSDL• communication protocol (RPC, HTTP, …)• marshalling/serialization• transformation to and from XSD to OWL

• Control flow of the service•Black/Grey/Glass Box view

• Protocol Specification• Abstract Messages

•Capability specification•General features of the Service

• Quality of Service• Classification in Service

taxonomies

OWL-S/WSDL Grounding

Service Grounding (How is it used?)

• Implementation-specific • Message formatting, transport

mechanisms, protocols, serializations of types

• Service Model + Grounding give everything needed for using the service

• Examples: HTTP forms, SOAP, KQML, CORBA IDL, OAA ICL, Java RMI

Grounding Example

• Transport: Secure HTTP• Protocol: HTTP Forms• Address: https://buybot.congo.com:4040/initsu

b.htm• Type Serializations

– ItemDescription (keywords): Set of DAML literals– PriceRange: pair of monetary units, ISO 5678– CreditCard:

https://transcredit.com/S1.daml#SecureTransferFormat

OWL-S Development Tools

• WSDL2OWLS. Available at http://www.daml.ri.cmu.edu/wsdl2owls

• OWL-S/UDDI matchmaker Available at• http://www.daml.ri.cmu.edu/matchmaker.• Complete implementation of OWL-S 1.1 AP

I

Other efforts to SWS

• Web Service Modeling Framework (WSML)- Web Service Modeling Ontology (WSMO)

• Internet Reasoning Service (IRS-II) and (IRS-III) are Semantic Web Services Framework, developed by KMI,

• …

References OWL-S

• The main repository of papers on OWL-S is at http://www.daml.org/services/owl-s/pub-archive.html

• The main source of information on OWL-S is the Web site http://www.daml.org/services/owl-s

• W3C reference http://www.w3.org/Submission/OWL-S/