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Dependable Web Service Compositions usng a Semantic Replication Scheme. LABORATÓRIO DE SISTEMAS DISTRIBUÍDOS – LASID DEPARTAMENTO DE CIÊNCIA DA COMPUTAÇÃO - DCC UNIVERSIDADE FEDERAL DA BAHIA - UFBA. Daniela Barreiro Claro 1. Raimundo José de Araújo Macêdo 2. SBRC 2008.

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Dependable Web Service Compositions usng a Semantic Replication Scheme

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Dependable web service compositions usng a semantic replication scheme l.jpg

Dependable Web Service Compositions usng a Semantic Replication Scheme

LABORATÓRIO DE SISTEMAS DISTRIBUÍDOS – LASID

DEPARTAMENTO DE CIÊNCIA DA COMPUTAÇÃO - DCC

UNIVERSIDADE FEDERAL DA BAHIA - UFBA

Daniela Barreiro Claro1

Raimundo José de Araújo Macêdo2

SBRC 2008

  • Dr. Daniela Barreiro Claro is supported by FAPESB (BOL2071/2006).

  • Prof. Raimundo José de Araujo Macêdo is supported by FAPESB and CNPQ(Edital Universal).


Outline l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Outline

  • Motivation

  • Dependability requirements for WSC

  • The SAREK approach

  • Experimental tests

  • Performance evaluation

  • Comparison with related work

  • Conclusion and future directions

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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Motivation l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Motivation

  • Web services are autonomous applications that can be published, located and invoked over the Internet.

  • Due to their potential for heterogeneous integration, companies are implementing their business as a Web service format.

  • However, a single Web service cannot fulfill a user request and need to be combined.

Web service Composition

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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Motivation4 l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Motivation

  • Whereas WS specifications cover dependable issues, no one handles the problem of dependable and automatic Web service compositions.

  • This raises another problem: a single WS failure, thus the failure of the whole composition.

  • Availability or continuity of service must be taken into account to apply WSC in critical applications.

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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Motivation5 l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Motivation

  • A commonly used technique for improving availability is to replicate services.

  • This work tackles the problem of dependability requirements of WSC, using ontologies to form a set of semantically alike replicas.

  • We propose a framework SAREK where a failure of a primary service can be masked by the execution of another service semantically compatible.

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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Required properties for wsc l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Required Properties for WSC

  • Some kinds of faults should be treated by a fault tolerant mechanism in order to reach the goal of a WSC.

    • unavailability of a Web service

    • partially operational WS

    • Internet disconnections

  • Some mechanisms have been introduced

    • FT-SOAP, WS-Reliability, WS-Replication, etc

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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Required properties for wsc7 l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Required Properties for WSC

  • Data Consistency

    • WSC should guarantee the integrity of data in its execution

  • Computation Availability

    • It is not possible to assume that all WS in a composition are reliable. A WSC should guarantee availability without knowing the reliability level of single WS

  • Scalability

    • WSC ability to handle a growing amount of WS

  • Transparency

    • WS is included and removed from a composition in a transparent way

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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The sarek approach l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

The SAREK approach

  • System model and assumptions

    • A set of activities m is the number of activities.

    • A set of services n is the number of services.

    • Candidate services is a subset of Service for a specific activity

    • A composition C is a sequence of activities performed by a set of services

  • WS are implemented as processes

  • Channels are assumed to be reliable

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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The sarek approach9 l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

The SAREK Approach

  • SAREK is a modified and enhanced version of SPOC1

  • SAREK is divided into two modules

    • The Planner Module

      • Aims to automatically determine the activities for a given composition

    • The Executor Module

      • Aims to execute the composition defined by the Planner

    • Both modules are replicated using a passive replication mechanism.

1. Claro D.B, Albers P. And Hao, J-K. A framework for automatic composition of RFQ Web services. In IEEE SCW/ WSCA-ICWS, Salt Lake City, USA. 2007

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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Slide10 l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

10


The planner module l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

The Planner Module

  • The Planner is divided into two main phases: Planning and Optimization

  • The Planning phase

    • It uses an AI Planning algorithm based on preconditions and effects

    • Interacts with OPS (an OWL ontology) to discover services

    • Each WS is described using an OWL-S format

    • This phase aims to determine which activity belongs to the composition in order to fulfill the user request

    • It main issue is the set of activities A that can reach the given request

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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The planner module12 l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

The Planner Module

  • The Optimization phase

    • Optimizes the combination of WS and activities

    • The values used to optimize are based on estimated values retrieved from each candidate Web service

    • It seems a quotation system

    • Produces a set of semantic similar compositions

    • We used a genetic algorithm called NSGA-II to get the Pareto optimal solutions, i.e. the compositions

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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The executor module l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

The Executor Module

  • This module executes the composition using the prefix mechanism

  • In order to provide fault tolerance both a transactional approach and a replication mechanism are applied.

    • Semantic replication scheme

    • Transactional Level

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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The executor module14 l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

The Executor Module

  • Semantic replication scheme

    • Faulty Web service can be replaced by a semantically similar service (transparency property)

    • Kind of spatial redundancy, because there is a set of compositions that achieve the same goal.

    • The prefix approach increases performance

      • Only the failed partition of the composition is re-executed

        and the prefix . It saves recovery time supposing that the service s3failed.

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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The executor module15 l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

The Executor Module

  • Transactional Level

    • Temporal redundancy mechanism, SAREK tries one more time to recover from a possible transient fault

    • If the problem persists, and no other semantic similar composition can be replaced, SAREK roll back the previous executed Web service

      • Using ACID or a compensation technique

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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Experimental tests l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Experimental Tests

  • Case Study

    • SAREK was applied to a bidding process for repairing public buildings.

  • Prototype implementation of SAREK

    • Java 1.5, Apache Tomcat 5.0, Axis 1.3, Jena API 2.3, OWL-S API 1.1.0 and MySQL Database 4.1

    • Experiments were carried out in single computer

      • Inter motherboard Core Duo, processor T2300 1.66 Ghz and 1Gb of RAM.

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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Simulated scenario l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Simulated scenario

  • 4 activities

    • supplyWood, supplyConcrete, supplyIron and buildStaircase

  • Each activity can be performed by 2 candidate services

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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Simulated scenario18 l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Simulated scenario

  • There is one WSDL operations for execution

    • String executeWS()

  • Results were produced by 2 runs

    • Without failures

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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Simulated scenario19 l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Simulated scenario

  • With failures (services 5, 3, 6 failed)

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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Performance evaluation l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Performance Evaluation

  • Each experiment was run 400 times for calculating the average time and standard deviation

  • Two kinds of experiments

    • A composition is fixed

    • A composition is randomly chosen

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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Performance evaluation21 l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Performance Evaluation

  • The overhead caused by faults for an increasing the number of forced Web services failures.

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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Related work l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Related Work

  • Comparison in the light of the required dependability properties for automatic WSC

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

22


Conclusion and future directions l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Conclusion and future directions

  • Challenges for achieving Dependable Web service compositions

    • Suggesting a set of required dependability properties.

  • To the best of our knowledge, SAREK is the first framework that provides such fault tolerant guarantees in WSC

  • Future works

    • Evaluate the fault tolerant mechanism in real scenarios

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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Thank you l.jpg

Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Thank you!

Daniela Barreiro Claro

dclaro@ufba.br

Raimundo Macêdo

macedo@ufba.br

http://www.lasid.ufba.br

LaSiD/DCC/UFBa

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

dclaro@ufba.br macedo@ufba.br Semantic Replication Scheme

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