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Software Architecture for Semantic Web Service

Execution

Semantic Web Services ClusterResearch Seminar

14 February 2005, Galway

Matthew Moran

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Structure

• Idea and motivation

• What is the state of the art?

• What’s missing and what is the contribution?

• Where is the novelty?

• Methodology

• Current research tasks – SWS and Grid

– SWS and Grounding

– WSMX Invocation

• Next steps

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Idea and Motivation

• A detailed architecture for a Semantic Web Services System– As a lightweight system integration platform

– Provide requirements analysis for the functionality

– Look beyond current components of WSMX

– Can be described using an Architecture Desc. Language

• Motivation– Web services: lots of specs but lack of coherence

– Lack of semantics holding back Web services for business

– Want to learn fundamentals of integration architectures and where other initiatives failed

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Initial TOC

• Introduction• State of the art

– Web services, SWS, Software system architectures• Functional requirements for SWS Architecture

– WSMX + security, reliability, transactionality, state, lifetime, …– Configuration requirements

• Architectural Description Languages• Detailed description of SWS architecture

– Components and interfaces • Relationship between SWS and Grid• Use case

– Deployment of SWS system in real industrial environment– Analysis of design validity

• Conclusions

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State of the Art

• Semantic Web Service environments– WSMX and OWL-S Virtual

• Conceptual WS and SWS architectures– WSA, WSMF, Chris Preist paper, REST

• Web service technology stack

• Integration systems

• Architectures of other software system types– Operating systems, Compilers, JVM, DBMS

– Middleware and distributed computing systems

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What is Missing

• A detailed architecture for a SWS environment – Functional components

• How they connect• What happens if they fail• How can they be bypassed

– Non-functional properties• Reliability• Security• Adaptability

• Use-case that demonstrates viability of SWS architecture design and provides metrics for analysis

• A formal description of this architecture• A way to simulate different execution scenarios

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Novelty

• No requirements document exists for SWS architecture– Extend WSMF description of functionality for successful

Web services to Semantic WS

• No technical architecture for a coherent Semantic Web Services architecture exists (with the exception of WSMX/DIP)

• No analysis of the validity of SWS technology exists for a real industrial-standard use-case

• No formal model of a SWS architectural model exists

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Methodology – Learning

• Web service technology stack• Software architecture design

– Patterns– Architecture Description Languages

• Formal languages for semantics – RDF, OWL, Petri-Nets for execution semantics

• Integration concepts– A2A, B2B, EAI

• Integration systems– TP-Monitors - Cics– Middleware – Corba, COM, J2EE– Commercial – BEA WebLogic, IBM Websphere, Oracle iAS, Iona

Artix, MS Biztalk, …– Grid computing

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Methodology – Year 1

• Actively learn ‘on the job’– WSMO and WSMX working groups

– Participation in DIP and ASG projects

– Organise and present at tutorials

– Present at business outreach meetings

• Publications (5 + tutorials)– Focus on topics

– Get feedback

– Learn about related research areas

• Select thesis topic – Write 4 page proposal

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Methodology – Year 2

• Finalize table of contents• Publications (focused on chapters in ToC)

– Grounding– State of the art in architecture– Security and WSMX– Grid and WSMX (ii)

• Continue active involvement in WSMX, WSMO & Projects• Establish suitable use-case

– Through DIP or ASG use cases– Through HP– Through business outreach partner

• Analyse use-case outcome• Populate thesis

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Current Research Tasks

• Service grounding at conceptual level– Mapping between WSMO and XML-Schema

Conceptual Framework

• Relationship between SWS and Grid – What can WSMX learn from Globus Toolkit

• Service interaction (Communication Manager)– Handling different transport protocols and faults

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Grounding at the Conceptual Level

XML Schema Conceptual Framework

XML Schema

XML Data Instance

WSMO Ontology Metamodel

WSMO Ontology

WSML Data Instance

Bidirectional mappings at conceptual level

Rules based on conceptual mappings

Rules based on conceptual mappings

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Relationship between SWS and Grid

WSMO: Conceptual Model

WSML: Language

WSMX: Architecture & Ref. Implementation

SemanticWeb Services

CompositionEvent-basedFramework

Discovery

Invocation Mediation

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Relationship between SWS and Grid

WSMO: Conceptual Model

WSML: Language

WSMX: Architecture & Ref. Implementation

SemanticWeb Services

Grid

Service StateIntrospection Service Lifetime

management

WSRF:WS-Resource

WS-ResourcePropertiesWS-ResourceLifetime

(OASIS)

CompositionEvent-basedFramework

Discovery

Invocation Mediation

SecurityGSI

Dynamic EndpointAddressing

WS-Addressing(W3C)

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Service Interaction – Send & Receive

• Use Web Service Implementation Framework (Apache WSIF)– Open source

– Dynamic invocation based on WSDL

– Abstracts binding details from service

• Handling QoS issues at message level– Faults

– Security

– Reliability

– Transactions

• Relationship between Communication Manager and:– Choreography

– Adaptors (including grounding)

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Next Steps

• Next draft of ToC

• Papers– Architecture of integration systems

– Invocation and grounding in WSMX

– Security and WSMX

– WSMX and Grid

– Describing WSMX with ADL

• Implementation– Communication Manager

– Grounding

• Use case:– Find a suitable use case

– Arrange to deploy WSMX to address the problem