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Semantic Web Services

Atilla ELÇİDept. of Computer Engineering

Eastern Mediterranean University

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Semantic Web Services- A Survey

SWS intro WSMO Approach: European approach OWL-S Approach: W3C SWSF Approach IRS-III Approach WSDL-S Approach Grounding: semantic vs syntactic description of

services Davies et al. Ch. 10.

SWS intro Current WS tech based on SOAP messaging, WSDL, and

UDDI technology is syntactic requiring manual process. FYI: see references for leads on How to WS. A different framework is required for semantic Web

services: Conceptual model Lang for formal syntax & semantics Execution environment

In order to enable fully flexible automated e-business, Semantic Web Services promise to automate tasks such as discovery, mediation, selection, composition, and invocation of services.

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WSMO Approach: schematics Components of Web Services Modelling Ontology (WSMO) Ref. Fig.

10.1

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WSMO Approach Design principles:

Web compliance: w/ W3C specs Ontology-based: data model Strict decoupling: independently specified resources Centrality of mediation: mediation provided centrally Ontological role separation: parts played by users/components Description vs implementation: seperated concerns Execution semantics: reference implementation (WSMX) Service vs Web service: separation of tool & result

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Conceptual model of WSMO Meta Object Facility (MOF): a meta-meta model

language Used in defining elements of WSMO ontology An abstract lang & framework for technology neutral

meta-models: specify, contruct, manage Four layers of MOF:

Meta meta-model: the language used for WSMO Meta model: WSMO itself (class, subClass, Attribute, type, cardinality,...) Model: actual ontologies, WSs, goals, mediators specs Info: actual data described by the model (grounding)

Exs: ontologies, Web services, goals, mediators: Described by non-functional properties Using mostly DC namespace elements

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WS Descr.: TheLanguage WSML The Web Service Modelling Language (WSML) is a

merger of: Description logics Logic programming F-Logic

Used in service description through: Ontology description: syntax & semantics Declarative functional description of goals & services:

syntactical framework (with implied Hoare-style semantics). => Transaction Logic?

Description of dynamics: choreagraphy & orchestration.

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WSML variants

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WSML Example: Amazon cart Ex. code in 10.2.2.2

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The Execution Environment The Web Services Modelling Execution Environment

(WSMX) for Web services: Discovery Selection Mediation, and Invocation.

A test bed of ideas and a reference implementation of WSMO.

WSMX info model: see Sourceforge Developed for the Eclipse Framework open source IDE. Ref. Fig. 10.3

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WSMX Architecture

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OWL-S Approach Revolves around the OWL-S:

OWL Web Service Ontology Part of the DAML Program A language for describing semantically rich Web services Based on OWL

Consists of the subontologies of “service” concept: Profile:

What a service does? Service presents ServiceProfile.

Process model: How it works? Service describedBy ServiceModel.

Grounding: How to access it? Service supports ServiceGrounding.

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OWL-S: Sub-ontologies of Service ServiceProfile: Profile sub-ontology. What a service does?

Advertising Constructing service requests Matchmaking

ServiceModel: Process model sub-ontology. How it works? Invocation Enactment Composition Monitoring Recovery

ServiceGrounding: Grounding sub-ontology. Accessing the service Data sources to message formats Protocols

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OWL-S ServiceProfile Service is a function of:

The organization that provides the service: Admin contact info

The function the service computes: Info xformation: I/O params State change caused: Pre/post-conditions

Characteristics of the service: Quality, category, and user-declared service

parameters

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OWL-S ServiceProfile: IOPE The function part simply lists the IOPE:

inputs, outputs, preconditions, effects No schema here to describe them. Simply links them to the Process Model part. Properties of the Profile Class:

hasParameter hasInput hasOutput hasPrecondition hasResult

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OWL-S ServiceModel: Process Process: Defines how to interact with the service

not the function code of the service. In a way, more detailed verison of the function

part of ServiceProfile! Processes and IOPEs are linked by the following

properties: hasParticipant -> Participant class (client, service) hasInput -> Input class hasOutput -> Output class hasLocal -> Local class hasPrecondition -> Condition class (required for exec.) hasResult -> Result class (effects, outputs)

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OWL-S ServiceModel: Process kinds Atomic processes:

Single step process: I -> O Involves no sub-process

Composite processes: Multi-step process With state memory Decomposable into atomic, simple, or

composite processes. Simple Processes.

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Control Structures:Decomposing a Composite Process Sequence Split:

Like threads to be executed concurrently Completes when all component processes are scheduled.

Split + Join: Like Split but completes when all component processes complete execution

Choice: Selecting a control construct to execute

Any-Order: Unspecified sequential order of execution

If-Then_Else: Just as common format

Iterate: Non-conditional looping

Repeat-While and Repeat-Until: Conditional looping

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OWL-S: Examples: BravoAirProcess.owl VehiclePartPriceService.owl How to do SWS: doc by Duygu

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SWSF Approach

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IRS-III Approach

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WSDL-S Approach

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Conclusions

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Books on SWS Modeling Semantic Web Services: The Web

Service Modeling Language by Jos de Bruijn Price: $59.95 Release Date: June 1, 2008

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Conferences: summer schools 4TH REASONING WEB SUMMER SCHOOL (RW 2008):

7-11 September, 2008, San Servolo Island, Venice. Appl Deadline: May 16, 2008.

PROGRAM1. Foundations of Knowledge representation and Reasoning2. Representing Knowledge with Controlled Natural Language Processing3. Semantic Multimedia4. Semantic techniques for Social Networks5. Semantic techniques for Bioinformatics6. Semantic Web Services

REGISTRATION FEE: 750 EUR which covers: - the volume of LECTURE NOTES published by Springer, - accommodation at San Servolo Island, - all meals, - social event.

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Conferences: summer schools ICCL Summer School 2008: COMPUTATIONAL

LOGIC AND COGNITIVE SCIENCE Technische Universität Dresden August 24 -- September 6, 2008

6th INTERNATIONAL SUMMER SCHOOL IN FORMAL LANGUAGES AND APPLICATIONS (formerly International PhD School in Formal Languages and Applications) Tarragona, Spain, July 21 - August 2, 2008 Organized by Research Group on Mathematical

Linguistics Rovira i Virgili University

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Conferences: summer schools THE SIXTH EUROPEAN SUMMER SCHOOL ON

ONTOLOGICAL ENGINEERING AND THE SEMANTIC WEB (SSSW-2008)   Cercedilla, near Madrid, Spain. 6-12 July, 2008.

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References John Davies, Rudi Studer, Paul Warren (Editors): Semantic Web

Technologies: Trends and Research in Ontology-based Systems, John Wiley & Sons (July 11, 2006). ISBN: 0470025964. Ch. 10.: pp. 191-236.

Web Services- How To: see the following: Deitel & al.: Ch. 21 in C# HTP, Pearson 2002. W3Schools: Web Services Tutorial W3C Web Services Activity. Hugo Haas: Tutorial: Foundations And Future Directions of Web

Services W3C Semantic Web Tools Wiki page:

Check Jena, SemWeb, Protégé, Swoop, etc.