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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

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
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

[email protected] [email protected] Semantic Replication Scheme

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motivation
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

[email protected] [email protected] Semantic Replication Scheme

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motivation4
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

[email protected] [email protected] Semantic Replication Scheme

4

motivation5
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

[email protected] [email protected] Semantic Replication Scheme

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required properties for wsc
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

[email protected] [email protected] Semantic Replication Scheme

6

required properties for wsc7
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

[email protected] [email protected] Semantic Replication Scheme

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the sarek approach
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

[email protected] [email protected] Semantic Replication Scheme

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the sarek approach9
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

[email protected] [email protected] Semantic Replication Scheme

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slide10
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

[email protected] [email protected] Semantic Replication Scheme

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the planner module
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

[email protected] [email protected] Semantic Replication Scheme

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the planner module12
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

[email protected] [email protected] Semantic Replication Scheme

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the executor module
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

[email protected] [email protected] Semantic Replication Scheme

13

the executor module14
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

[email protected] [email protected] Semantic Replication Scheme

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the executor module15
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

[email protected] [email protected] Semantic Replication Scheme

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experimental tests
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

[email protected] [email protected] Semantic Replication Scheme

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simulated scenario
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

[email protected] [email protected] Semantic Replication Scheme

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simulated scenario18
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

[email protected] [email protected] Semantic Replication Scheme

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simulated scenario19
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

[email protected] [email protected] Semantic Replication Scheme

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performance evaluation
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

[email protected] [email protected] Semantic Replication Scheme

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performance evaluation21
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

[email protected] [email protected] Semantic Replication Scheme

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related work
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

[email protected] [email protected] Semantic Replication Scheme

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conclusion and future directions
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

[email protected] [email protected] Semantic Replication Scheme

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thank you
Experimental Tests

Performance Evaluation

Comparison with Related Work

Conclusion

Outline

Motivation

Properties for WSC

SAREK approach

Thank you!

Daniela Barreiro Claro

[email protected]

Raimundo Macêdo

[email protected]

http://www.lasid.ufba.br

LaSiD/DCC/UFBa

Daniela Barreiro Claro Raimundo Macêdo Dependable Web Service Compositions using a

[email protected] [email protected] Semantic Replication Scheme

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