SemanticGov WSMO, WSML and WSMX Seminar

www.semantic-gov.org

SemanticGov WSMO, WSML and WSMX Seminar

Tomas Vitvar, Holger Lausen, Adrian Mocan, Tomas Haselwanter, Michal Zaremba

SemanticGov WSMO/L/X Seminar6-7 April 2006, Innsbruck

2www.semantic-gov.org

Agenda

09.00-10.30 Semantic Web Services and WSMO Tomas Vitvar (DERI Galway)

10.30-11.00 Coffee Break

11.00-11.30 Web Service Modeling Language (WSML) Holger Lausen (DERI Innsbruck)

11.30-12.30 Semantic Web Services Techniques

(Discovery, Invocation, Mediation)

Adrian Mocan (DERI Innsbruck)

12.30-14.00 Lunch Break

14.00-15.00 WSMX – Principles, Architecture and Implementation Adrian Mocan (DERI Innsbruck)

15.00-15.30 Coffee Break

15.30-16.00WSMO/L/X Tools Adrian Mocan (DERI Innsbruck)

Marin Dimitrov (Ontotext)

16.00-17.00 Demos/Hands-on Session Adrian Mocan (DERI Innsbruck)

Thomas Haselwanter (DERI Innsbruck)


<Semantic Web Services and WSMO>

Tomas Vitvar


Overview

• Introduction to Semantic Web Services• Web Service Modeling Ontology


500 million user

more than 3 billion pages

Static WWWURI, HTML, HTTP

Semantic Web and Web Services



Serious Problems inSerious Problems ininformation finding,information finding,information extracting,information extracting,Information representing,Information representing,information interpreting and information interpreting and information maintaining.information maintaining.

Semantic WebRDF, RDF(S), OWL




Bringing the Bringing the computer back computer back as a device for as a device for computationcomputation


Dynamic Web ServicesUDDI, WSDL, SOAP




Bringing Bringing the Web the Web to its full to its full potentialpotential


Dynamic Web ServicesUDDI, WSDL, SOAP

Intelligent WebServices



• The next generation of the WWW

• Information has machine-processable and machine-understandable semantics

• Not a separate Web but an augmentation of the current one

• Ontologies as basic building block

Semantic Web


Formal, explicit specification of a shared conceptualization

commonly accepted understanding

conceptual model of a domain

(ontological theory)

unambiguous terminology definitions

machine-readability with computational

semantics

Semantic Web – Ontology Definition


Concept – Conceptual entity of a domain

Property – Attributes describing a concept

Relation – Relationships between concepts or properties

Axiom – Coherency description between Concepts / Properties / Relations using logical expressions

Person

Student Professor

Lecture

isA – hierarchy (taxonomy)

name email

numberresearch

field

topiclecture

nr.

attends holds

holds(Professor, Lecture) =>Lecture.topic = Professor.researchField

Semantic Web – Ontology Example


• Ontology Languages:– expressivity – reasoning support – web compliance

• Ontology Reasoning: – large scale knowledge handling – stable & scalable inference machines

• Ontology Management Techniques: – editing and browsing – storage and retrieval – versioning and evolution Support

• Ontology Integration Techniques: – ontology mapping/aligning, merging

Semantic Web – Ontology Technology


• Loosely coupled, reusable components

• Encapsulate discrete functionality

• Distributed

• Accessible over standard internet protocols

• Add new level of functionality on top of the current web

Web Services


Web Services – Architecture


• Web Service Description Language • W3C effort, WSDL 2 final construction phase

Web Services – WSDL


• Universal Description, Discovery, and Integration Protocol • OASIS driven standardization effort• Information stored in UDDI

– White Pages– Name of Business, Contact Information– Description of the Company

– Yellow Pages– Business Classification Information– Based on NAICS, or Geographical Index– List of Products (multiple entries)

– Green Pages– Technical Information about services– Example: business processes, binding info, etc.

Web Services – UDDI


• Simple Object Access Protocol • W3C Recommendation • XML Data Transport

– Sender <-> receiver– Protocol Binding– Communication Aspects– Messages – content

Web Services – SOAP


• Only Syntactical Information Descriptions– Syntactic support for discovery, composition and execution– Web Service usage and integration needs to be supported

manually

• No Semantic mark-up for content and services• No support for Semantic Web

Web Services – Difficulties


Semantic Web Technology

+

Web Service Technology

=> Semantic Web Services as integrated solution for realizing the vision of the next generation of the Web

• allow machine supported data interpretation• ontologies as data model

• messaging, invocation of services• security, etc.

Semantic Web Services


• Service Model – framework for description of Web Services and related aspects

• Ontologies as Information Model – support ontologies and make use of ontology languages for definition of underlying information model

• Define semantically driven techniques for total or partial automation of the web service execution process

Semantic Web Services


• Publication – Make the description of a Web service available on the Web

• Discovery – Detect suitable services for a solving given task

• Selection – Choose the most appropriate services among the suitable ones

according to user’s preferences

• Composition– Combine more services to achieve a goal

• Mediation – Solve mismatches (data, protocol, process) among different

services

Semantic Web Services – Execution Process (1)


• Invocation– Invoke services according to consumption interface and

programmatic conventions

• Monitoring– Control and monitor the execution process

• Compensation– Provide transactional support (i.e. commit/rollback)

• Replacement– Facilitate the substitution of services by equivalent ones

• Auditing– Verify that service execution occurred in the expected way

Semantic Web Services – Execution Process (2)


Overview

• Introduction to Semantic Web Services• Web Service Modelling Ontology


• WSMO defines conceptual model for Semantic Web Services– Ontology of core elements for Semantic Web Services – Formally defined using WSML language– Derived from the Web Service Modelling Framework (WSMF)

• WSMO defines requirements for Web Service Modelling Language (WSML)

• WSMO defines framework for architecture and execution environment (WSMX)

• WSMO is developed as part of ESSI cluster

WSMO – Scope


A Conceptual Model for SWS

A Formal Language for WSMO

A Rule-based Language for SWS

Execution Environment for WSMO

WSMO – Working Groups


• Web Compliance • Ontology-Based • Goal-driven • Strict Decoupling • Centrality of Mediation • Description versus Implementation • Execution Semantics

WSMO – Design Principles


Objectives that a client wants toachieve by using Web Services

Provide the formally specified terminologyof the information used by all other components

Semantic description of Web Services: - Capability (functional)- Interfaces (usage)

Connectors between components with mediation facilities for handling heterogeneities

WSMO D2, version 1.2, 13 April 2005 (W3C submission)

WSMO – Top Level Elements


• Every WSMO elements is described by properties that contain non-functional aspects of web services

• Dublin Core Metadata Set– Used for resource management

• Versioning Information– Evolution support

• Quality of Service Information– Availability of services, reliability

• Other – Owner, financial aspects, etc.

Non-Functional Properties


Dublin Core Metadata Contributor Coverage Creator Description Format Identifier Language Publisher Relation Rights Source Subject Title Type

Quality of Service Accuracy NetworkRelatedQoSPerformanceReliability RobustnessScalability Security Transactional Trust

Other Financial Owner TypeOfMatch Version

List of Non-functional Properties


Provide the formally specified terminologyof the information used by all other components Semantic description of Web

Services: - Capability (functional)- Interfaces (usage)



WSMO Ontologies


• Ontologies are used as the ‘data model’ throughout WSMO – all WSMO element descriptions rely on ontologies– all data interchanged in Web Service usage are ontologies– Ontology reasoning and semantic information processing

• WSMO Ontology Language WSML– conceptual syntax for describing WSMO elements – logical language for axiomatic expressions (WSML Layering)

• WSMO Ontology Design

– Modularization: import / re-using ontologies, modular approach for ontology design

– De-Coupling: heterogeneity handled by OO Mediators

WSMO Ontologies – usage and design principles


• Non functional properties• Imported Ontologies

– importing existing ontologies where no heterogeneities arise

• Used mediators – OO Mediators (ontology import with terminology mismatch handling)

• Ontology Elements:– Concepts – set of concepts that belong to the ontology, incl.– Attributes – set of attributes that belong to a concept– Relations – define interrelations between several concepts– Functions – special type of relation– Instances – set of instances that belong to the represented ontology– Axioms – axiomatic expressions in ontology (logical statement)

Ontology Specification


WSMO Web Services

Provide the formally specified terminologyof the information used by all other components Semantic description of Web

Services: - Capability (functional)- Interfaces (usage)




WSMO Web Service Description

Web ServiceImplementation(not of interest in Web Service Description)

Choreography --- Service Interfaces ---

Capability

functional description

WS

WS

- Advertising of Web Service- Support for WS Discovery

client-service interaction interface for consuming WS - External Visible Behavior- Communication Structure - ‘Grounding’

realization of functionality by aggregating other Web Services - functional decomposition - interaction with aggregated WS

Non-functional Properties

DC + QoS + Version + financial

- Complete item description- Quality aspects

WS

Orchestration


WSMO Web Service – Capability Specification

• Non functional properties, Imported Ontologies, Used mediators

• Preconditions – what a web service expects in order to be able to provide its

service (conditions over the input)• Assumptions

– conditions on the state of the world that has to hold before the Web Service can be executed

• Postconditions – Describes the result of the Web Service in relation to the

input, and conditions on it• Effects

– conditions on the state of the world that hold after execution of the Web Service (i.e. changes in the state of the world)


WSMO Web Service – Interface Specification

• Service Interface – consumption and interaction – Choreography and Orchestration – described as sub-

elements of WSMO Web Service Interface• Choreography

– External Visible Behaviour of a Web Service– Aspects of the workflow of a Web Service where Interaction is

required • Communication Structure – messages sent and received and

order of messages

• Orchestration– Decomposition of Web Service functionality– Interaction with aggregated web services


WSMO Web Service – Interface Specification

• Description Requirements– Dynamics of information interchange

• Formal Framework – Abstract State Machines (ASM)• core principles: state-based, state definition by formal algebra,

guarded transitions for state changes• Reasoning on Web Service Interfaces (validation of

conversation)• Mediation support on Web Service interfaces (i.e. process

mediation)– Ontologies – underlying data model– Grounding – executable underlying communication

technology for interaction


• VTA example:

• Choreography = how to interact with the service to consume its functionality • Orchestration = how service functionality is achieved by aggregating other Web

Services

VTAService

Date

Time

Flight, Hotel

Error

Confirmation

Hotel Service

Flight Service

Date, Time

Hotel

Error

Date, Time

Flight

Error

When the service is requested

When the service requests

Choreography and Orchestration – Example


Service Interface Description Model – ASM

• Vocabulary Ω: – ontology schema(s) used in service interface description – usage for information interchange: in, out, shared, controlled

• States ω(Ω): – a stable status in the information space – defined by attribute values of ontology instances

• Guarded Transition GT(ω): – state transition – general structure: if (condition) then (action) – additional constructs: add, delete, update


Service Interface Example

Ωin hasValues concept A [ att1 ofType X att2 ofType Y]…

a memberOf A [ att1 hasValue x att2 hasValue y]

a memberOf A [ att1 hasValue x, att2 hasValue y]

b memberOf B [ att2 hasValue m]

IF (a memberOf A [ att1 hasValue x ])THEN (b memberOf B [ att2 hasValue m ])

State ω1 Guarded Transition GT(ω1) State ω2

Ωout hasValues concept B [ att1 ofType W att2 ofType Z]…

Vocabulary: - Concept A in Ωin - Concept B in Ωout

Received instance a Sent instance b


WSMO Goals






• Ontological De-coupling of Requester and Provider • Goal-driven Architetcure:

– requester formulates objective independently – ‘intelligent’ mechanisms detect suitable services for solving the

Goal– allows re-use of Services for different purposes

• Derived from different AI-approaches for intelligent systems

– Intelligent Agents (BDI Architectures) – Problem Solving Methods

• Requests may in principle not be satisfiable• Ontological relationships & mediators used to link goals to

web services

WSMO Goal


WSMO Goal Specification

• Non functional properties, Imported Ontologies, Used mediators

• Requested Capability – describes service functionality expected to resolve the

objective – defined as capability description from the requester

perspective • Requested Interface

– describes communication behaviour supported by the requester for consuming a Web Service (Choreography)


WSMO Mediators






WSMO Mediators

• Heterogeneity … – Mismatches on structural / semantic / process levels – Occur between different components that shall interoperate– Especially in distributed & open environments like the Internet

• Concept of Mediation: – Mediators as components that resolve mismatches– Mediation cannot be always fully automated– Several types of mediators defined by WSMO

• OOMediators, WWMediators, GGMediators, WGMediators


WSMO Mediators – Overview


WSMO Mediator

uses a Mediation Service via

Source Component

Source Component

TargetComponent 1 .. n

1

Mediation Services

- as a Goal

WSMO Mediators – General Approach


OO MediatorMediation Service

Train ConnectionOntology (s1)

Purchase Ontology (s2)

Train Ticket Purchase Ontology

Mediation Services

Goal:“merge s1, s2 and s1.ticket subclassof s2.product”

Discovery

Merging 2 ontologies

WSMO OO Mediator – Example


• Aim:– Support specification of Goals by re-using existing Goals – Allow definition of Goal Ontologies (collection of pre-defined

Goals)– Terminology mismatches handled by OO Mediators

• Example: Goal Refinement

GG MediatorMediation Service

Source Goal“Buy a ticket”

Target Goal “Buy a Train Ticket”

postcondition: “aTicket memberof trainticket”

WSMO GG Mediator


• WG Mediators:– link a Web Service to a Goal and resolve occurring mismatches – match Web Service and Goals that do not match a priori– broader range of Goals solvable by a Web Service

• WW Mediators:– enable interoperability of heterogeneous Web Services– support automated collaboration between Web Services – OO Mediators for terminology import with data level mediation– Process Mediation for making Business Processes interoperable

WG and WW Mediators


• Other Frameworks/approaches to SWS– OWL-S

• Ontology and Language to describe SWS• Strong relation with Semantic Web and Web Services• No explicit notion of mediatiors (mediation is a by-product of orchestration

process)– WSDL-S

• Semantic Annotations for WSDL– IRS

• Internet Reasoning Service• Recently based on WSMO model

• Standardization– OASIS SEE TC

• Standardization of architecture– W3C

• Semantic Annotations for Web Services WG• Rule Interchange Format WG• W3C Submissions: WSMO/L/X, OWL-S, WSDL-S

Related Work


</Semantic Web Services and WSMO>

Question and Answers


<Web Service Modeling Language>

Holger Lausen


Agenda

• Overview of Semantic Web Languages• Inferences in OWL DL• Introduction to Web Service Modeling Language• Demo


Ontology Languages in the Semantic Web

The (in)famous layer cake(s)


Ontology Languages in the Semantic Web

• Dimensions to consider– Layering between languages– Modeling Style / Epistemology – Expressiveness– Reasoning support (e.g. Query Answering vs. Entailment)– Assumptions built into language, e.g.

• Unique Names vs. Not Unique Names Assumption

• Open vs. Closed World Semantics


Layer Cake 2000

Tim Berners Lee, XML Conference, 2000


Layer Cake 2005

Tim Berners Lee, International Semantic Web Conference, 2005


Simplified Stack (from a logicians point of view)

Description Logic Programming

Description Logic Logic Programming

FOL++


Inferences in OWL DL


OWL - Language

• Three species of OWL– OWL full is union of OWL syntax and RDF

– OWL DL restricted to DL fragment (¼ DAML+OIL)

– OWL Lite is “simpler” subset of OWL DL

• Semantic layering– OWL DL ¼ OWL full within DL fragment

• OWL DL based on SHIQ Description Logic• OWL DL Benefits from many years of DL research

– Well defined semantics

– Formal properties well understood (complexity, decidability)

– Known reasoning algorithms

– Implemented systems (highly optimised)


OWL by Example – Subsumption Reasoning

• Class(BusDriver complete intersectionOf(Person restriction(drives someValuesFrom (Bus))))

• Class(Bus partial Vehicle)• Class(Driver complete intersectionOf(Person

restriction(drives someValuesFrom (Vehicle))))

• A bus driver is a person that drives a bus• A bus is a vehicle• A driver is a person that drives a vehicle

Class(Driver partial BusDriver)

Taken from (includes many other DL inferences) http://www.cs.man.ac.uk/~horrocks/Teaching/cs646/Slides/why.ppt


OWL by Example – (not) Unique Names / Equality Reasoning

• ObjectProperty(hasPassenger domain(FlightSeat) range(Passenger))

• Class(FlightSeat partial restriction(hasPassenger maxCardinality(1)))

• Individual(seat1 type(FlightSeat) value(hasPassenger Mary) value(hasPassenger John))

• A flight seat represents the seats in a particular flight. The property has passenger associates a seat in a flight with a passenger.

• A seat may only have one passenger, which is guaranteed by the restriction maxCardinality(1).

• The individual seat1 is an instance of flight seat; seat1 has two values for the property has passenger, namely Mary and John.

john = mary


OWL by Example – Type Inferences

• ObjectProperty(hasPassenger domain(FlightSeat) range(Passenger))

• Individual(seat1 type(FlightSeat))• Individual(seat2 type(FlightSeat)

value(hasPassenger seat1))

• A flight seat represents the seats in a particular flight. The property has passenger associates a flight seat (domain) with a passenger (range).

• seat1 is a flight seat• seat 2 is a flight seat and has a passernger named seat1

Individual(seat3 type(Passenger)


OWL Summary

• Good For Classification / Bad for Instance Retrieval• Open World Assumption• Non Unique Name Assumption• Classical Logic

– Description Logic

– Monotonic Logic

– decidability/tractability properties

– it is the fragment of logic that can be computationally explored around the existential quantifier.

• No support for data type predicates (+,-,*,/)• No support for meta modeling (OWL DL)• Only unary and binary predicates• Layering (Lite / DL) not really justified


Web Service Modeling Language


• Aim – to provide a language (or a set of interoperable languages) for representing the elements of WSMO:– Ontologies, Web services, Goals, Mediators

• WSML provides a formal language for the conceptual elements of WSMO, based on:– Description Logics– Logic Programming– First-Order Logic– Frame Logic

Web Service Modeling Language (WSML)


Variants of WSML


WSML-Core

• Basic interoperability layer between Description Logics and Logic Programming paradigms

• Based on Description Logic Programs– Expressive intersection of Description Logic SHIQ and Datalog– Allows to take advantage of many years of established research

in Databases and Logic Programming– Allows reuse of existing efficient Deductive Database and Logic

programming reasoners

• Some limitations in conceptual modeling of Ontologies– No cardinality constraints– Only “inferring” range of attributes– No meta-modeling


WSML-DL

• Extension of WSML-Core• Based on the Description Logic SHIQ

– Entailment is decidable– Close to DL species of Web Ontology Language OWL– Many efficient subsumption reasoners

• Some limitations in conceptual modeling of Ontologies– No cardinality constraints– Only “inferring” range of attributes– No meta-modeling

• Limitations in logical expressions– From Logic Programming point-of-view, there is a lack of:

• N-ary predicates• Chaining variables over predicates• (Default) negation


WSML-Flight

• Extension of WSML-Core• Based on the Datalog,

– Ground entailment is decidable– Allows to take advantage of many years of established research

in Databases and Logic Programming– Allows reuse of existing efficient Deductive Database and Logic

programming reasoners

• No limitations in conceptual modeling of Ontologies– Cardinality constraints– Value constraints for attributes– Meta-modeling


WSML-Rule

• Extension of WSML-Flight; based on Horn fragment of F-Logic• Ground entailment is undecidable• Turing complete• Allows to take advantage of many years of established research in

Logic Programming• Allows reuse of existing efficient Logic programming reasoners• Extends WSML-Flight logical expressions with:

– Function symbols– Unsafe rules

• From Description Logic point-of-view, there is a lack of:– Existentials– Disjunction– (Classical) negation– Equality


WSML-Full

• Extension of WSML-Rule and WSML-DL• Based on First Order Logic with nonmonotonic extensions• Entailment is undecidable• Very expressive• Extends WSML-DL logical expressions with:

– Chaining variables over predicates– Function symbols– Nonmonotonic negation– N-ary predicates

• Extends WSML-Rule with:– Existentials– Disjunction– Classical negation– Equality

• Specification of WSML-Full is open research issue


Demo


Online Reasoner


Resources

• http://www.wsmo.org/wsml/wsml-syntax – Specificiation, Tools, News

• Online Demos:– WSML Rule Reasoner

• http://tools.deri.org/wsml/rule-reasoner/• http://tools.deri.org/wsml/validator/

• Tools:– WSMO4J (API & reference implementation)

• http://wsmo4j.sourceforge.net/

– Reasoner:• WSML 2 Reasoner (can be used with several reasoners)

– http://dev1.deri.at/wsml2reasoner/

• MINS Reasoner (Datalog + negation + function symbols)– http://dev1.deri.at/mins/


</Web Service Modeling Language>

Question and Answers


<Semantic Web Services Techniques >

Adrian Mocan


SWS Challenges

• Dynamic (and automatic) Web services interoperation

• Techniques required for:– Discovery

• how are Web services found and selected?

– Composition• how to aggregate Web Services into a complex functionality?

– Conversation • how to ensure automated interaction of Web Services?

– Invocation• how to access and invoke Semantic Web Services?

– Mediation• how are data and protocol mismatches resolved?

• Systems for automated Web service usage :– Resource editing and management – Functional components – APIs, execution control, integrated & flexible architectures


Virtual Travel Agency Use Case

• Tomas is employed in DERI Galway and wants to book a flight and a hotel for the SemanticGov Seminar

• The start-up company VTA provides tourism and business travel services based on Semantic Web Service technology

• => how does the interplay of Tomas, VTA, and other Web Services

look like?

Michael

Flight Booking

Hotel Booking

uses & aggregates

Service Provider I

Service Provider II

provides

contract

contract

VTA


Domain Ontologies

• All terminology used in resource descriptions are based on ontologies and all information interchanged should be ontology instances

• Domain Ontologies needed for this Use Case: – Trip Reservation Ontology, Location Ontology, Date and Time Ontology,

Purchase Ontology, … possibly more

• Ontology Design for the Semantic Web – Real ontologies

– (re-)use existing, widely accepted ontologies

– Modular ontology design

– … is a very difficult and challenging task• determine agreed conceptualization of domain • correct formalization (e.g. misuse of is_a / part_of relations) • => requires expertise in knowledge engineering


“Trip Reservation” Ontology

• Defines the terminology for trips (traveling, accommodation, holiday / business travel facilities) and reservations

• Provided by community of interest (e.g. Austrian Tourism Association)

• Main concepts: – TRIP

• describes a trip (a journey between locations) • passenger, origin & destination, means of travel, etc.

– RESERVATION • describes reservations for tickets, accommodation, or complete trips • customer, trip, price, payment

– RESERVATION REQUEST / OFFER / CONFIRMATION

• Uses other ontologies: – Location Ontology for origin & destination specification – Date and Time Ontology for departure, arrival, duration information – Purchase Ontology for payment related aspects


Goal Description

• “Book flight and hotel for the SemanticGov Seminar for Tomas”

• Goal capability postcondition: get a trip reservation for this

goal _"http://www.wsmo.org/examples/goals/SemGovSem" importsOntology _"http://www.wsmo.org/ontologies/tripReservationOntology", … capability postcondition definedBy ?tripReservation memberOf tr#reservation[ customer hasValue fof#tomas, reservationItem hasValue ?tripSemGovSem] and ?tripSemGovSem memberOf tr#trip[ passenger hasValue fof#tomas, origin hasValue loc#galway, destination hasValue loc#innsbruck, meansOfTransport hasValue ?flight, accomodation hasValue ?hotel] and ?flight[airline hasValue tr#AerLingus] memberOf tr#flight and ?hotel[name hasValue “Hotel Innsbruck”] memberOf tr#hotel.


VTA Service Description

• Book tickets, hotels, amenities, etc. • Capability description (pre-state)

capability VTAcapability sharedVariables ?creditCard, ?initialBalance, ?item, ?passenger precondition definedBy ?reservationRequest[ reservationItem hasValue ?item, passenger hasValue ?passenger, payment hasValue ?creditcard, ] memberOf tr#reservationRequest and ((?item memberOf tr#trip) or (?item memberOf tr#ticket)) and ?creditCard[balance hasValue ?initialBalance] memberOf po#creditCard.

assumption definedBy

po#validCreditCard(?creditCard) and (?creditCard[type hasValue po#visa] or

?creditCard[type hasValue po#mastercard]).


VTA Service Description

• Capability description (post-state)

postcondition definedBy ?reservation[ reservationItem hasValue ?item, customer hasValue ?passenger, payment hasValue ?creditcard ] memberOf tr#reservation.

effect definedBy reservationPrice(?reservation, ?tripPrice) and ?finalBalance = (?initialBalance - ?ticketPrice) and ?creditCard[po#balance hasValue ?finalBalance].


Discovery


Web Service Discovery

Tomas Objective: „Book a flight and a hotel for me for the SemGovSem.“

Service Registry WS Discoverer

has

searchesVTA

result set includes

Goal definition


Discovery Techniques

• Different techniques available – Trade-off: ease-of-provision <-> accuracy – Resource descriptions & matchmaking algorithms

– Key Word Matching • match natural language key words in resource descriptions

– Controlled Vocabulary• ontology-based key word matching

– Semantic Matchmaking • … what Semantic Web Services aim at

Ease of provision

Possible A

ccuracy


Matchmaking Notions & Intentions

• Exact Match: – G, WS, O, M x. (G(x) <=> WS(x) )

• PlugIn Match: – G, WS, O, M x. (G(x) => WS(x) )

• Subsumption Match: – G, WS, O, M x. (G(x) <= WS(x) )

• Intersection Match: – G, WS, O, M x. (G(x) WS(x) )

• Non Match: – G, WS, O, M ¬x. (G(x) WS(x) )

= G = WS

X

Keller, U.; Lara, R.; Polleres, A. (Eds): WSMO Web Service Discovery. WSML Working Draft D5.1, 12 Nov 2004.


Discoverer Architecture

• Discovery as central Semantic Web Services technology

• Integrated Discoverer Architectures:

Resource Repository (UDDI or other)

Keyword-/ Classification-based Filtering

Controlled Vocabulary Filtering

Semantic Matchmaking

usable Web Service

efficient narrowing of search space (relevant services to be inspected)

retrieve ServiceDescriptions

invoke Web Service


Choreography in Discovery

Requested Interface (Chor)1) send request2) select from offer3) receive confirmation

Goal

defines

VTA

VTA WS ‘Trip Booking’

Capability

Interface (Chor.)1) get request2) provide offer 3) receive selection4) send confirmation

Interface (Orch.)1) flight request2) hotel request 3) book flight4) book hotel

Flight WS

Capability


Orch. ..

Hotel WS

Capability


Orch. ..

provides

Requested Capabilitybook flight & hotel

- both choreography interfaces given (“static”)- correct & complete consumption of VTA => existence of a valid MEP?

- VTA Orchestration & Chor. Interfaces of aggregated WS given=> existence of a valid MEP between VTA and each aggregated WS?

- Choreography in Discovery as a central reasoning task in Service Interfaces


internal business logic of

Web Service(not of interest in Service

Interface Description)

Choreography in Discovery

• A valid MEP exists if: – 1) Signature Compatibility

• homogeneous ontologies

• compatible in- and outputs

– 2) Behavior Compatibility• start state for interaction

• a termination state can be reached without any additional input





Behavior Compatibility Example

ΩG(ωØ) = Ø

ΩG(ω1) = request(out)

ΩG(ω2a) = offer(in), changeReq(out)

if Ø then request ΩVTA(ωØ) = Ø

ΩVTA(ω1) = request(in), offer(out)

if request then offer

if cnd1(offer) then changeReq

ΩG(ω2b) = offer(in), order(out)

if cnd2(offer) then order

ΩVTA(ω2a) = changeReq(in),offer(out)

if changeReq then offer

ΩVTA(ω2b) = order(in), conf(out)

if order then conf

ΩG(ω3) = offer(in), conf(in)

if conf then Ø

Goal Behavior Interface VTA Behavior Interface

Start

ω2(C)

ω1(C)

ω3(C)

ω4(C)

Termination

valid MEP existent


Orchestration Validation Example

• Orchestration is valid if valid MEP exists for interactions between the orchestrating and each aggregated Web Service, done by choreography discovery

if Ø then (FWS, flightRequest) if request then offer

if order then confirmation

VTA Web Service Orchestration

Start (VTA, FWS)

Termination (VTA, FWS)

if flightOffer then (HWS, hotelRequest)

if selection then (FWS, flightBookingOrder)

if selection, flightBookingConf then (HWS, hotelBookingOrder)

Flight WS Behavior Interface

if request then offer

if order then confirmation

Hotel WS Behavior InterfaceStart

(VTA, HWS)

Termination (VTA, HWS)


Grounding


WSMO Grounding

• Motivation– It’s a WSDL and XML Schema world

• Background– XML, XML Schema, what’s been done before

• Approaches to data grounding– Three possible approaches, one chosen

• Creating the mappings– Methodology, identifying mappings, next steps

• Grounding WSMO Choreography


Motivation

• Web services being created and deployed now and for the next few years will be described using WSDL and XML Schema

• Want to define the mechanism for how WSMO service descriptions can be grounded to WSDL – Ground WSMO ontologies to XML Schema– Ground WSMO choreography descriptions to WSDL operations


Background – XML

• Standard language for sharing data across systems,especially on the Web

• Application-dependent tag set great flexibility• Many XML based languages for all kinds of purposes• Strong tool support: parsers, editors, storage, querying

• Semantics must be known by receiver in advance; can not be determined from the document itself


Background – XML Schema

• Defines the structure of XML documents– Legal elements and attributes– Order, cardinalities of child elements– Default and fixed values for elements and attributes

• Components of XML Schema– Element declarations (global or local)– Attribute declarations (global or local)– Simple types

• Built-in or defining constraints on values of built-in types

– Complex types• For elements

• Define attributes, child elements

• Extend or restrict definition of an existing complex type


Background – Previous Work

• Comparing XML schema languages (DTD, XS) to Ontologies

XML schema language Ontologies

Define vocabulary and constraints for XML docs

Formal specification of shared domain theory

Structure Meaning, no explicit structure

• Embedding semantic metadata into XML– Complement structure with semantics

• Lifting XML representation to OWL and RDF– We will take a similar approach

• Lowering ontologies to XML schema– More expressive to less expressive

Other Related Areas of Work


Approaches to Mapping


Approach to Mapping #1

• Transformation between XML as defined in WSDL and the XML syntax for a target WSMO ontology– Using XSLT or other XML transformation language

• Advantage– People already know XSLT

• Disadvantage– XML syntax of WSML does not reflect data structure, the XSLT

becomes complex



• Map directly between XML and WSML instances– Using a mapping language specific for this task

• Advantage– Specific language most natural (optimized for this)

• Disadvantage– Yet another mapping language



• Create WSMO Ontology from Schema in WSDL – Define mappings from conceptual framework for XML Schema to

WSMO Ontology metamodel– Generate ontology– Create set of executable mapping rules for data instances

• Advantages– Uses WSMO data mediation– In simplest case no manually-created mapping required

• Disadvantage– Ontology-level mapping may be complex


Creating the Mappings


Creating the Mappings Explained

• Define a mapping between the XML Schema Conceptual Model to the WSMO Ontology Metamodel

• Automatically create a WSMO ontology from specific XML Schema

• Create the bidirectional mapping rules to be used for the transformation between XML instances and WSMO instances.– Created at the same time as the generation of the

WSMO ontology from an XML Schema– These mapping are completely derived from the actions

described in the first two bullet points


Creating the Mappings (I)

• The generated ontology is sufficient for designer’s needs• Mapping rules to get from instances of WSMO to

instances of XML and vice-versa are created automatically


Creating the Mappings (II)

• Designer wishes to use a specific book ontology• Generated ontology + rules created as before• Additional data mediation needs to be defined

(using existing ontology mapping tools)


Grounding Illustrated

unnecessaryin simple

case


Grounding WSMO Choreography

• Choreography representation in WSMO– States (made up of concepts) and transitions

• Concept modes– Some concepts represent in or out messages– In, out, shared

• Grounding property– Specifies a set of URIs grounding that concept– URIs point to WSDL In, Out or Fault messages

• URIs for identifying messages in WSDL 2.0

http://example.com/#wsdl.interfaceMessageReference(PrinterInterface/print/In)

• WSDL WSMO – manual (with tool support)• WSMO WSDL – auto generation of WSDL

– In case WSDL doesn’t exist yet


WSMO Grounding – Summary

• Links from WSMO to the WSDL and XML Schema world• Needed to describe an existing WSDL service• Three steps in approach

– Define mappings from metamodel of XML Schema to that of WSMO

– Use the mappings to generate WSMO ontologies– Also generate mapping rules that can be applied at runtime to lift

and lower data instances

• Simple scenarios need no data mediation• Choreography grounded to WSDL messages

– Can go to underlying space instead


Mediation


Mediation

• Heterogeneity as inherent characteristic of (Semantic) Web: – Heterogeneous terminology– Heterogeneous languages / formalisms – Heterogeneous communication protocols and business processes

• WSMO identifies Mediators as top level elements, i.e. central aspect of Semantic Web Services – Levels of mediation: data, functional, processes– WSMO Mediators: ooMeditor, ggMediator, wgMediator, wwMediator

• Approach: declarative, generic mismatch resolution – Classification of possible & resolvable mismatches – Mediation definition language & mediation patterns– Execution environment for mappings


Data Level Mediation

• Scope– Solving terminological mismatches

• Related Aspects / Techniques: – Ontology Integration (Mapping, Merging, Alignment) – Data Lifting & Lowering– Transformation between Languages / Formalisms

• Terminology Mismatches Classification – Conceptualization Mismatches

• same domain concepts, but different conceptualization• different levels of abstraction • different ontological structure • => resolution only includs human intervention

– Explication Mismatches • mismatches between:

– T (Term used), D (definition of concepts), C (real world concept)• => automated resolution partially possible


Functional Level Mediation

• Scope– Solving functional mismatches between goals and/or ws

• Related Aspects/Techniques– Discovery– Semantic Matchmaking

• Matchmaking Mismatches

= G/WS = G/WS

X

Exact Match Subsumption Match Intersection Match No MatchPlugIn Match


Process Level Mediation

• Scope– Resolves communication mismatches and establish behavior

compatibility

• Related Aspects/Techniques– Data and control flow composition

• Process Mismatches– Signature terminology mismatches (need for data level mediation)

– Communication/behavior mismatches

Business Partner1Business Partner1

Business Partner2Business A

B B



A B

B A



A and BA

B



A

BA and B

PM

PM

PM

PM



A

AckA

APM


WSMO Mediators and Mediation Levels

• ooMediator– Data Level Mediation

• ggMediator– Data Level Mediation– Functional Level Mediation

Ex:

• wgMediator– Data Level Mediation– Functional Level Mediation– Process Level Mediation

• wwMediator– Data Level Mediation– Functional Level Mediation– Process Level Mediation







WW

Med

iator


</Semantic Web Services Techniques >

Questions and Answers


<WSMX – Principles, Architecture and Implementation>

Adrian Mocan


WSMX Introduction

• Software framework for runtime binding of service requesters and service providers

• WSMX interprets service requester’s goal to– discover matching services– select (if desired) the service that best fits– provide mediation (if required)– make the service invocation

• Is based on the conceptual model provided by WSMO• Has a formal execution semantics• Service Oriented and event-based architecture

– based on microkernel design using technologies as J2EE, Hibernate, Spring, JMX, etc.


WSMX Motivation

• Provide middleware ‘glue’ for Semantic Web Services– Allow service providers focus on their business

• Provide a reference implementation for WSMO– Eat our own cake

• Provide an environment for goal based service discovery and invocation– Run-time binding of service requester and provider

• Provide a flexible Service Oriented Architecture– Add, update, remove components at run-time as needed

• Keep open-source to encourage participation– Developers are free to use in their own code

• Define formal execution semantics– Unambiguous model of system behaviour


WSMX Usage Scenario


WSMX Usage Scenario - P2P

• A P2P network of WSMX ‘nodes’• Each WSMX node described as a SWS• Communication via WSML over SOAP• Distributed discovery – first aim• Longer term aim - distributed execution environment



Peer

Internet

Message

Message

Internet

Message

MessagePeer

WSMX SWSARCHITECTURE



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anag

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Storage Reasoning

Communication (external)

Fault Handling Monitoring

Data MediationProcess

Mediation

Discovery Adaptation Composition Choreography

Application Services Layer

Problem Solving Layer

Base Services Layer

End User Tools Developer Tools

Internet

Message

MessagePeerPeer

Internet

Message

Message


Development Process & Releases

• The development process for WSMX includes:– Establishing its conceptual model– Defining its execution semantics– Develop the architecture– Design the software – Building a working implementation

• Releases:

2005 2006

January 2005 (WSMX 0.1.6)

July 2005 (WSMX 0.2.0) current status of components

March 2006 (WSMX 0.3.0)

November 2004 (WSMX 0.1.5)


Design Principles

• Strong Decoupling & Strong Mediation– autonomous components with mediators for interoperability

• Interface vs. Implementation– distinguish interface (= description) from implementation

(=program)

• Peer to Peer– interaction between equal partners (in terms of control)

WSMO Design Principles == WSMX Design Principles

== SOA Design Principles


Benefits of SOA

• Better reuse– Build new functionality (new execution semantics) on

top of existing Business Services

• Well defined interfaces – Manage changes without affecting the Core System

• Easier Maintainability– Changes/Versions are not all-or-nothing

• Better Flexibility


Service Oriented State

• The interface to the service is implementation-independent

• The service can be dynamically invoked – Runtime binding

• The service is self-contained– Maintains its own state


Messaging

• Messaging is peer-to-peer facility• Distributed communication

– Loosely coupled

• Sender does not need to know receiver (and vice versa)• Asynchronous mechanism to communicate between

software applications


WSMX Architecture

MessagingMessaging

Application Management

Application Management

Service Oriented

Architectures

Service Oriented

Architectures


Selected Components

• Adapters• Parser• Invoker• Choreography • Process Mediator• Discovery• Data Mediator• Resource Manager• Reasoning

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Base Services Layer


Internet

Message

MessagePeerPeer

Internet

Message

Message


Adapters

• To overcome data representation mismatches on the communication layer

• Transforms the format of a received message into WSML compliant format

• Based on mapping rules


Parser

• WSML compliant parser– Code handed over to wsmo4j initiative

http://wsmo4j.sourceforge.net/

• Validates WSML description files• Compiles WSML description into internal memory model• Stores WSML description persistently

(using Resource Manager)


Communication Mgr – Invoker

• WSMX uses – The SOAP implementation from Apache AXIS – The Apache Web Service Invocation Framework (WSIF)

• WSMO service descriptions are grounded to WSDL• Both RPC and Document style invocations possible• Input parameters for the Web Services are translated

from WSML to XML using an additional XML Converter component.

Network

InvokerApache

AXISXML

ConverterMediatedWSML Data

XML WebService

SOAP


Choreography

• Requester and provider have their own observable communication patterns– Choreography part of WSMO

• Choreography instances are loaded for the requester and provider– Both requester and provider have their own WSMO descriptions

• Choreography Engine– Evaluation of transition rules

• Prepares the available data

– Sends data to the Process Mediator• The Process Mediator filters, changed or even replaced data

– Receive data from PM and forwards it to the Communication manager• Data to be finally sent to the communication partner


Process Mediator

• Requester and provider have their own communication patterns

• Only if the two match precisely, a direct communication may take place

• At design time equivalences between the choreographies’ conceptual descriptions is determined and stored as set of rules

• The Process Mediator provides the means for runtime analyses of two choreography instances and uses mediators to compensate possible mismatches


Process Mediator – Addressed mismatches


Business Partner2Business A

B B



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Process Mediation Example


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Discovery

• Responsible for finding appropriate Web Services to achieve a goal (discovery)

• Current discovery component is based on simple matching– Keywords identified in the NFP of the goal– Matched against NFPs of the published WSs – Variable set of NFPs to be considered for this process– To be extended

• Values in NFPs might be concepts from ontologies

• More elaborate string matching algorithms

• Advanced semantic discovery in prototypical stage


Discovery

Resource Repository (UDDI or other)

Keyword-/ Classification-based Filtering

Controlled Vocabulary Filtering

Semantic Matchmaking

usable Web Service

efficient narrowing of search space (relevant services to be inspected)

retrieve ServiceDescriptions

invoke Web Service


Data Mediator

• Ontology-to-ontology mediation• A set of mapping rules are defined and then executed• Initially rules are defined semi-automatic• Create for each source instance the target instance(s)

Target Ontology

Source Ontology

Storage

Mappings

Mappings

Source Instance

Target Instance

Run-time ComponentDesign-time Component

Data Mediation


Run-Time Data Mediator

• Main Mediation Scenario: Instance Transformation

• Inputs– Incoming data

• Source ontology instances

• Features– Completely automatic process– Grounding of the abstract mappings to a concrete language

• WSML

– Uses a reasoner to evaluate the mapping rules• MINS

• Outputs– Mediated data

• Target ontology instances

Data Mediation


Ontology Mapping Language

• Language Neutral Mapping Language – mapping definitions on meta-layer (i.e. on generic ontological constructs) – independent of ontology specification language – “Grounding” to specific languages for execution (WSML, OWL, F-Logic)

• Main Features: – Mapping Document (sources, mappings, mediation service) – direction of mapping (uni- / bidirectional) – conditions / logical expressions for data type mismatch handling, restriction of

mapping validity, and complex mapping definitions – mapping constructs:

• classMapping, attributeMapping, relationMapping (between similar constructs) • classAtrributeMapping, classRelationMapping, classInstanceMapping• instanceMapping (explicit ontology instance transformation)

– mapping operators: • =, <, <=, >, >=, and, or, not • inverse, symmetric, transitive, reflexive • join, split


Ontology O2

Mapping Language Example

Human - name

Adult Child

Person- name - age

tomas memberOf Person- name = Tomas Vitvar- age = 28

classMapping(unidirectional o2:Person o1.Adult attributeValueCondition(o2.Person.age >= 18))

This allows to transform the instance ‘tomas’ of concept person in ontology O2 into a valid instance of concept ‘adult’ in ontology O1

Ontology O1


Resource Manager

• Stores internal memory model to a data store• Decouples storage mechanism from the rest of WSMX• Data model is compliant to WSMO API• Independent of any specific data store implementation

i.e. database and storage mechanism


Reasoner

• Mins – Datalog + Negation + Function

Symbols Reasoner Engine– Features

• Built-in predicates • Function symbols • Stratified negation

• WSMO4J– validation, serialization and parsing

• WSML2Reasoner– Reasoning API

• mapping fromWSML to a vendor-neutral rule representation

– Contains: • Common API for WSML Reasoners• Transformations of WSML to tool-specific input data

(query answering or instance retrieval)

• WSML-DL-Reasoner– Features:

• T-Box reasoning (provided by FaCT++) • Querying for all concepts • Querying for the equivalents, for the children, for the

descendants, for the parents and for all ancestors of a given concept

• Testing the satisfiability of a given concept with respect to the knowledge base

• Subsumption test of two concepts with respect to the knowledge base

• Wrapper of WSML-DL to the XML syntax of DL used in the DIG interface


System Entry Points

• achieveGoal (Document): Context

• getWebServices (Document): Context

invokeWebService(Document, Context): Context


Define “Business” Process

Discover Web Services

Create Choreography

Created

Discover Services

Mediate Data

Mediate Data

Return Mediated Data


Return Web Services

Check Choreography

Confirmed

Call Invoker

Confirmed

Start

End


Generate Wrappers for Components


Create Choreography

Created

Discover Services

Mediate Data

Mediate Data



Return Web Services

Check Choreography

Confirmed

Call Invoker

Confirmed

Start

End

Discovery Wrapper

Data Mediator Wrapper

ChoreographyWrapper

Communication Manager Wrapper

Registry of known components


Context Data

PROCESS CONTEXT


Create Choreography

Created

Discover Services

Mediate Data

Mediate Data



Return Web Services

Check Choreography

Confirmed

Call Invoker

Confirmed

Start

End

Discovery Wrapper


ChoreographyWrapper


Registry of known components

Choreography objectMediated objects,

Web Services entities

ErrorsExceptions


Event-based Implementation

MediatorDiscoveryChoreographyCommunication

Manager

Core – Manager

“Business” Process – Internal Workflow

Choreography Wrapper

Discovery Wrapper

implements Mediator Interface

Event and Notification Distribution/Delivery Mechanism



events events eventsnotifications notifications notificationsnotificationsevents


Execution Semantics

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WSMT – Web Services Modelling Toolkit

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ChoreographyWrapper

Choreography

Interface

Reasoner Interface

Reasoner




Service Providers

Web Service 1

Web Service 2

Web Service p

...

Service Requesters



requester


ComponentWrapper

New Component

Interface

Set of Web Servicedescriptions expressedin requester’s ownformat returned togoal requester.



• Complete the functionality for all the boxesE

xecu

tion

Man

agem

ent

Ver

tical

Ser

vice

s e.

g. S

ecur

ity

Storage Reasoning




Mediation




Base Services Layer


Internet

Message

MessagePeerPeer

Internet

Message

Message


WSMX Conclusions

• Conceptual model is WSMO • End to end functionality for executing SWS• Has a formal execution semantics• Real implementation • Open source code base at SourceForge• Event-driven component architecture• Growing functionality - developers welcome


WSMX @ Sourceforge.net


</WSMX – Principles, Architecture and Implementation>



<WSMO/L/X Tools>

Adrian Mocan, Marin Dimitrov


Web Service Modeling Toolkit (WSMT)

Adrian Mocan


Web Services Modeling Toolkit

• The aim of the Web Services Modeling Toolkit (WSMT) is to provide high-quality tools for designing, mediating and using Semantic Web Services, through the WSMO paradigm.

• The focus is currently on the following areas:– Creation of ontologies, web services, goals and mediators in

WSMO– Creation of mappings between pairs of ontologies to allow

runtime instance transformation– Management of Execution Environments for Semantic Web

Services like WSMX and IRSIII


Engineering Semantic Descriptions

in WSML


WSML Perspective

• Perspectives in the Eclipse framework allow for a number of Editors and views to be grouped and positions.

• The WSML perspective offers editors and views related to engineering of semantic descriptions in WSMO through the WSML language.

• Other General features include:– WSML file validation– Problems view (errors and warnings on files in the workspace)– Label highlighting (marking of errors and warnings in navigator

view)


WSML Editors and Views in the WSML perspective

EditorsWSML Text Editor

WSML Conceptual Editor

WSML Visualizer

ViewsNavigator view

Problems view

WSML Reasoner


Editors and Views in the WSML perspective



WSML Visualizer

ViewsNavigator view

Problems view

WSML Reasoner





WSML Visualizer

ViewsNavigator view

Problems view

WSML Reasoner





WSML Visualizer

ViewsNavigator view

Problems view

WSML Reasoner





WSML Visualizer

ViewsNavigator view

Problems view

WSML Reasoner





WSML Visualizer

ViewsNavigator view

Problems view

WSML Reasoner





WSML Visualizer

ViewsNavigator view

Problems view

WSML Reasoner


Ontology to Ontology Mapping


Ontology to Ontology Mapping

• As it will never be the case that one universal ontology will ever exist, and it is unlikely that one single ontology will exist for each domain, there is a need for mediating between different descriptions of the same domain.

• Within the WSMT we use the Abstract Mapping Language created by the Ontology Management Working Group to describe the relationships between two WSML ontologies.

• These mappings can be used by an execution environment at runtime to mediate between these two ontologies.


Editors, Views for the Abstract Mapping Language

EditorsAML Text Editor

AML Conceptual Editor

AML View Based Editor

ViewsConcept 2 Concept View

Attribute 2 Attribute View

Concept 2 Attribute View

Attribute 2 Concept View

Status View










Status View










Status View










Status View










Status View










Status View










Status View










Status View


Web Services and Execution Environments


WSDL Invocation Tool


WSMX Management Tool


WSMO Studio

Marin Dimitrov


</WSMO/L/X Tools>



<Demos>


WSMT


WSMX Demo - Scenario

Client

Stock Transaction Service

Stock InformationService

WSMX

ChoreographyEngine

ChoreographyEngine

OrchestrationEngine

ChoreographyEngine


</Demos>


References


References

• The central location where WSMO work and papers can be found is WSMO Working Group: http://www.wsmo.org

• WSMO languages – WSML Working Group: http://www.wsml.org

• WSMO implementation – WSMX working group : http://www.wsmx.org– WSMX open source can be found at: https://sourceforge.net/projects/wsmx/


References

• [WSMO Specification]: Roman, D.; Lausen, H.; Keller, U. (eds.): Web Service Modeling Ontology, WSMO Working Draft D2, final version 1.2, 13 April 2005.

• [WSMO Primer]: Feier, C. (ed.): WSMO Primer, WSMO Working Draft D3.1, 18 February 2005.

• [WSMO Choreography and Orchestration] Roman, D.; Scicluna, J., Feier, C. (eds.): Ontology-based Choreography and Orchestration of WSMO Services, WSMO Working Draft D14, 01 March 2005.

• [WSMO Use Case] Stollberg, M.; Lausen, H.; Polleres, A.; Lara, R. (ed.): WSMO Use Case Modeling and Testing, WSMO Working Drafts D3.2; D3.3.; D3.4; D3.5, 05 November 2004.

• [WSML] de Bruijn, J. (Ed.): The WSML Specification, WSML Working Draft D16, 03 February 2005.

• [Arroyo et al. 2004] Arroyo, S., Lara, R., Gomez, J. M., Berka, D., Ding, Y. and Fensel, D: "Semantic Aspects of Web Services" in Practical Handbook of Internet Computing. Munindar P. Singh, editor. Chapman Hall and CRC Press, Baton Rouge. 2004.

• [Berners-Lee et al. 2001] Tim Berners-Lee, James Hendler, and Ora Lassila, “The Semantic Web”. Scientific American, 284(5):34-43, 2001.


References

• [Bussler, 2003] Bussler, C. (2003): B2B Integration. Berlin, Heidelberg: Springer.

• [Cimpian and Mocan, 2005] Emilia Cimpian, Adrian Mocan: WSMX Process Mediation Based on Choreographies , 1st International Workshop on Web Service Choreography and Orchestration for Business Process Management (BPM 2005), September 2005, Nancy, France

• [Chen et al., 1993] Chen, W., Kifer, M., and Warren, D. S. (1993). HILOG: A foundation for higher-order logic programming. Journal of Logic Programming, 15(3):187-230.

• [Haller et al., 2005] A. Haller, E. Cimpian, A. Mocan, E. Oren, and C. Bussler. WSMX - A Semantic Service-Oriented Architecture. International Conference on Web Services (ICWS 2005), July 2005.

• [Kerrigan, 2006] Mick Kerrigan: Web Service Selection Mechanisms in the Web Service Execution Environment (WSMX), Proceedings of the 21st Annual ACM Symposium on Applied Computing (SAC), April, 2006, Dijon, France

• [Mandell and McIIraith, 2003] Daniel J. Mandell and Sheila A. McIlraith. Adapting BPEL4WS for the Semantic Web: The Bottom-Up Approach to Web Service Interoperation. In Proceedings of the Second International Semantic Web Conference (ISWC2003)

• [Mocan and Cimpian, 2005] Adrian Mocan, Emilia Cimpian: Mapping Creation Using a View Based Approach, 1st International Workshop on Mediation in Semantic Web Services (Mediate 2005), December 2005, Amsterdam, Netherlands


References

• [Domingue et al., 2004] Domingue, J. Cabral, L., Hakimpour, F., Sell D., and Motta, E., (2004) IRS-III: A Platform and Infrastructure for Creating WSMO-based Semantic Web Services WSMO Implementation Workshop (WIW), Frankfurt, Germany, September,2004

• [Feier et al., 2005] C. Feier, A. Polleres, R. Dumitru, J. Domingue, M. Stollberg, and D. Fensel. Towards intelligent web services: The web service modeling ontology (WSMO). International Conference on Intelligent Computing (ICIC), April 2005.

• [Fensel, 2001] Dieter Fensel, “Ontologies: Silver Bullet for Knowledge Management and Electronic Commerce”, Springer-Verlag, Berlin, 2001.

• [Fensel and Bussler, 2002] Fensel D. and Bussler C., "The Web Service Modeling Framework, WSMF," Electronic Commerce Research and Application, vol. 1, 2002

• [Fensel, 2004] D. Fensel: Triple Space computing - Semantic Web Services based on persistent publication of information. In Proceedings of IFIP International Conference on Intelligence in Communication Systems, Pages 43-53, Bangkok, Thailand, November 2004.

• [Gruber, 1993] Thomas R. Gruber, “A Translation Approach to Portable Ontology Specifications”, Knowledge Acquisition, 5:199-220, 1993.

• [Grosof et al., 2003] Grosof, B. N., Horrocks, I., Volz, R., and Decker, S. (2003). Description logic programs: Combining logic programs with description logic. In Proc. Intl. Conf. on the World Wide Web (WWW-2003), Budapest, Hungary.


References

• [Haselwanter et al., 2005] Haselwanter, T.; Zaremba, Ma.., Zaremba Mi.: Enabling Components Management and Executions Semantics in WSMX. In Proceedings of the 2nd International WSMO Implementation Workshop (WIW 2005), Innsbruck, Austria, June 2005.

• [Keller et al., 2004] Keller, U.; Lara, R.; Polleres, A. (Eds): WSMO Web Service Discovery. WSML Working Draft D5.1, 12 Nov 2004.

• [Keller et al., 2005] Keller, U.; Lara, R.; Lausen, H.; Polleres, A.; Fensel, D.: Automatic Location of Services. In Proc. of the 2nd European Semantic Web Symposium (ESWS2005), Heraklion, Crete, 2005.

• [Kifer et al., 1995] Kifer, M., Lausen, G., and Wu, J. (1995). Logical foundations of object-oriented and frame-based languages. JACM, 42(4):741-843.

• [Kiffer et al., 2004] M. Kifer, R. Lara, A. Polleres, C. Zhao, U. Keller, H. Lausen and D. Fensel: A Logical Framework for Web Service Discovery. Proc. 1st. Intl. Workshop SWS'2004 at ISWC 2004,Hiroshima, Japan, November 8, 2004, CEUR Workshop Proceedings, ISSN 1613-0073

• [Li and Horrocks, 2003] Lei Li and Ian Horrocks. A software framework for matchmaking based on semantic web technology. In Proc. of the Twelfth International World Wide Web Conference (WWW 2003), 2003

• [Paolucci et al., 2002a] Massimo Paolucci, Takahiro Kawamura, Terry R. Payne, Katia Sycara; Importing the Semantic Web in UDDI. In Proceedings of Web Services, E-business and Semantic Web Workshop, 2002

• [Paolucci et al., 2002b] Massimo Paolucci, Takahiro Kawamura, Terry R. Payne, Katia Sycara; "Semantic Matching of Web Services Capabilities." In Proceedings of the 1st International Semantic Web Conference (ISWC2002), 2002


References

• [Pan and Horrocks, 2004] Pan, J. Z. and Horrocks, I. (2004). OWL-E: Extending OWL with expressive datatype expressions. IMG Technical Report IMG/2004/KR-SW-01/v1.0, Victoria University of Manchester. Available from http://dl-web.man.ac.uk/Doc/IMGTR-OWL-E.pdf.

• [Preist, 2004] Preist, C.: A Conceptual Architecture for Semantic Web Services. In Proceedings of the 3rd International Semantic Web Conference (ISWC 2004), 2004, pp. 395 - 409.

• [Pollers et al., 2005] Axel Polleres, Holger Lausen, Jos de Bruijn and Dieter Fensel. WSML - A Language Framework for Semantic Web Services. W3C Workshop on Rule Languages for Interoperability, April 2005.

• [Stencil Group] - www.stencilgroup.com/ideas_scope_200106wsdefined.html

• [Stolberg et al., 2004] Stollberg, M.; Keller, U.; Fensel. D.: Partner and Service Discovery for Collaboration on the Semantic Web. Proc. 3rd Intl. Conference on Web Services (ICWS 2005), Orlando, Florida, July 2005.

• [Stolberg et al., 2005] M. Stollberg, E. Cimpian, and D. Fensel. Mediating Capabilities with Delta-Relations. In Proceedings of the First International Workshop on Mediation in Semantic Web Services, co-located with the Third International Conference on Service Oriented Computing (ICSOC 2005), Amsterdam, the Netherlands, 2005.

• [Stollberg et al., 2006] Michael Stollberg, Emilia Cimpian, Adrian Mocan, Dieter Fensel: A Semantic Web Mediation Architecture, Canadian Semantic Web Working Symposium (CSWWS 2006), June 2006, Québec city, Canada

• [Zaremba and Bussler, 2005] Zaremba, M. and Bussler, C.: Towards Dynamic Execution Semantics in Semantic Web Services. In Proceedings of the WWW 2005 Workshop on Web Service Semantics: Towards Dynamic Business Integration, 2005.

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SemanticGov WSMO, WSML and WSMX Seminar

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