Semantic Web Services

1
Semantic Web Services

• Atilla ELÇI
• Dept. of Computer Engineering
• Eastern Mediterranean University

2
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.

3
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.

4
WSMO Approach schematics

• Components of Web Services Modelling Ontology
  (WSMO) Ref. Fig. 10.1

5
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

6
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

7
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). gt Transaction Logic?
• Description of dynamics choreagraphy
  orchestration.

8
WSML variants
9
WSML Example Amazon cart

• Ex. code in 10.2.2.2

10
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

11
WSMX Architecture
12
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.

13
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

14
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

15
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

16
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 -gt Participant class (client,
  service)
• hasInput -gt Input class
• hasOutput -gt Output class
• hasLocal -gt Local class
• hasPrecondition -gt Condition class (required for
  exec.)
• hasResult -gt Result class (effects, outputs)

17
OWL-S ServiceModel Process kinds

• Atomic processes
• Single step process I -gt O
• Involves no sub-process
• Composite processes
• Multi-step process
• With state memory
• Decomposable into atomic, simple, or composite
  processes.
• Simple Processes.
• A (utility) view of atomic/composite process.

18
Control StructuresDecomposing 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

19
OWL-S Examples

• BravoAirProcess.owl
• VehiclePartPriceService.owl
• How to do SWS doc by Duygu

20
SWSF Approach
21
IRS-III Approach
22
WSDL-S Approach
23
Conclusions
24
Books on SWS

• Modeling Semantic Web Services The Web Service
  Modeling Language by Jos de Bruijn
• Price 59.95
• Release Date June 1, 2008

25
Conferences summer schools

• 4TH REASONING WEB SUMMER SCHOOL (RW 2008)
• 7-11 September, 2008, San Servolo Island, Venice.
• Appl Deadline May 16, 2008.
• PROGRAM
• Foundations of Knowledge representation and
  Reasoning
• Representing Knowledge with Controlled Natural
  Language Processing
• Semantic Multimedia
• Semantic techniques for Social Networks
• Semantic techniques for Bioinformatics
• 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.

26
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

27
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.

28
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.