Composing Web Services on the Semantic Web by Brahim Medjahed

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1 Composing Web Services on the Semantic Web by Brahim Medjahed Presented by Dohan Kim Lichun Zhu

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Composing Web Services on the Semantic Web by Brahim Medjahed. Presented by Dohan Kim Lichun Zhu. Outline. Semantic Description of Web Services Composability Model for Web Services Automatic Composition of Web Services Summarization and Conclusion. Semantic Description of Web Services. - PowerPoint PPT Presentation

Transcript of Composing Web Services on the Semantic Web by Brahim Medjahed

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Composing Web Serviceson the Semantic Web

by Brahim Medjahed

Presented by

Dohan Kim

Lichun Zhu

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Outline

Semantic Description of Web Services

Composability Model for Web Services

Automatic Composition of Web Services

Summarization and Conclusion

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Semantic Description of Web Services

Web Services Description Language (WSDL)

Extending WSDL with Semantic Capabilities

Providers, Composers, and Consumers

Automatic Composition of Web Services The approach for combining the concepts of Web

Services and Ontology

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Service

Binding

Name

Ontology-based description of Web Services ( WSDL Concept)

Operation

Input

Output

Name

Parameter

Name

DataType

1:N

1:N

1:N

1:N

1:1

1:1

1:1

1:1

1:{0,1}

1:{0,1}

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Semantic Description of Web Services

Mode Notification, One-way, Solicit-response, Request-response

Message A Message M is defined as a tuple ( P, T, U, R ) P is a set of parameter names T: P → DataTypes U: P → Units R: P → Roles

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Service

Binding

Name

Ontology-based description of Web Services ( Revisited)

Operation

Input

Output

Name

Parameter

Name

DataType

1:N

1:N

1:N

1:N

1:1

1:1

1:1

1:1

1:{0,1}

1:{0,1}

Mode

Unit

BusinessRole

1:1

1:1

1:1

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Semantic Description of Web Services

Purpose

Function, Synonyms, Specialization Function : Business functionality defined within a

given taxonomy Synonyms : A set of alternative function names Specialization : A set of characteristics of an

operation’s function

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Semantic Description of Web Services

Category

Domain, Synonyms, Specialization Domain : Area of interest defined within a given

taxonomy Synonyms : A set of alternative domains Specialization : A set of characteristics of an

operation’s domain

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Semantic Description of Web Services

Quality

Fees, Security, Privacy Fees : Dollar amount needed to execute an operation Security : A boolean that specifies whether an operati

on’s messages are securely exchanged Privacy : A set of input and output parameters that ar

e not divulged to external entities

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Service

Binding

Name

Ontology-based description of Web Services

Operation

Input

Output

Name

Parameter

Name

DataType

1:N

1:N

1:N

1:N

1:1

1:1

1:1

1:1

1:{0,1}

1:{0,1}

Mode

Unit

BusinessRole

1:1

1:1

1:1

Purpose

Category

Function Synonym Specialization

Domain Synonym Specialization

Quality

Fees Security Privacy

Description

Description

1:1

1:1

1:1

1:1

1:N

1:N1:1

1:1

1:1

1:1

1:N

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Semantic Description of Web Services

Defining Web Services and Operation

Web Service

A Web service WSi is defined by a tuple: ( Descriptioni, OPi, Bindingsi, Purposei, Categoryi )

Operation

An operation OPik is defined by a tuple : ( Descriptionik, Modeik, Inik, Outik, Purposeik, Categoryi

k, Qualityik)

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Composability model for Web Services

Mode and Binding Composability

Message Composability

Operation Semantics Composability

Qualitative Composability

Composition Soundness

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Composability model for Web Services

Mode Composability

Two operations are mode composable if mode of each operation is paired as follows:

( notification, one-way), ( one-way, notification) ( solicit-response, request-response) ( request-response, solicit-response)

Binding Composability

WSi =( Di, Oi, Bi, Pi, Ci ), WSj =( Dj, Oj, Bj, Pj, Cj ) Two services are binding composable if Bi ∩ Bj ≠Ø

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Composability model for Web Services

Message Composability

A message consists of one or more parameters, each having a certain data type

Data Type Compatible (Direct vs Indirect Compatible) Input message of a service operation may use only a

subset of the parameters of an output message Checking data type compatibility between input and o

utput operation Checking Unit and Business Role between input and

output operation

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Composability model for Web Services

OPik in WSi = (Dik, Mik, Inik, Outik, Pik, Cik, Qik) OPjl in WSj = (Djl, Mjl, Injl, Outjl, Pjl, Cjl, Qjl)

Operation Semantics Composability Pik is compatible with Pjl

Cik is compatible with Cjl

Qualitative Composability Qik.Fees ≥ Qjl.Fees (Qik .Security = true) ⇒ (Qjl.Security = true) Qik.Privacy ⊆ Qjl.Privacy

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Composability model for Web Services

Composition Soundness

Test whether composite services provides an added value

Combining airline and hotel services Combining airline and lemon check services ?

Composition Templates Stored Templates

A Composition of services are sound if its template is a subgraph of a stored template

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Automatic Composition of Web Services

Four conceptually separated phases for automatic composition of Web Services

Specification Phase

Matchmaking Phase

Selection Phase

Generation Phase

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Automatic Composition of Web Services

Specification Phase

Composite Service Specification Language ( CSSL ) High level description of composite services Specification of the control flow between composite

service operations

Example : CSSL - Car Broker Composite Service

<service name=“car broker”/> <category domain=“brokerage”> <binding name=“SOAP”/> ........ (continued)

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Automatic Composition of Web Services

CSSL - Car broker composite service (continued)

………. <message name=“offer”> <parameter name=“price” type=“float” unit=“US dollar” role=“extende

dPrice”/> <parameter name=“make” type=“string” ....../> <parameter name=“model” type=“string” ....../> <pararmeter name=“year” type=“gYear” ....../> <parameter name=“mileage” type=“integer” ....../> </message>

.......

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Automatic Composition of Web Services

CSSL - Car broker composite service (continued)

………. <operation name=“receiveSpecialOffers” mode=“one way”/> <input name=“offer”/> <category domain=“automobile dealer”> <synonyms> <synonym value=“car dealer”/></synonyms> <purpose function=“price-sales catalogue”/> <quality> <fees value=0/> ....... </operation> <flow source=“getPayingHistory” target=“applyForFinancing”>

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Automatic Composition of Web Services

Matchmaking phase

Generating composition plans using a matchmaking algorithm

Mapping each operation of the composite service to one or more operations of existing service and check composability.

Example functions of the algorithm purpose_compatible(), category_compatible(), quality_composa

ble(), message_composable(), sound()

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Automatic Composition of Web Services

Selection phase

Quality of Composition ( QoC ) parameters Ranking, Relevance, Completeness

Composition Ranking( CT, STi ) =

Composition Relevance =

Composition Completeness =

Plans with the highest ranking are returned first

1

( )

( )i

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kk

R ST

R ST

| |

| |iE E

E

| ( ) |

| |i

i

Composable O

O

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Automatic Composition of Web Services

Generation phase

Generating a detailed description of a composite service

• List of outsourced services• Mapping between composite and component service operations• Mapping between messages and parameters• Flow of control and data between component services

Target language for CSSL specification• Web Service Flow Language( WSFL), XLANG, etc

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Target Language Example ( WSFL )

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Conclusion

Automatically generate composite services from high-level specifications of the desired composition

Semantic description of Web Services Mode, Message, Operation,Purpose, Category, etc.

Composability model for Web Services

Automatic Composition of Web Services Specification, Matchmaking, Selection and Generation Phase

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Questions and Answers

Thank You !