Dynamic Web Service Selection for Workflow

Optimisation

Lican Huang, David W. Walker,

Yan Huang, Omer F. Rana

Presented by Lican Huang

School of Computer Science, Cardiff University

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Outline

•Introduction

• Framework

• Implementation

•Conclusion & Future work

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WOSE Project (Workflow Optimisation Services for e-Science Applications)

Funded by the EPSRC

Cardiff University, Imperial College and Daresbury Laboratory

Primary investigator: David.W.Walker

.

Introduction--background

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Introduction-- motivation

(1)Multiple copies of a service with different performance or other user defined set of criteria; and these services cannot be selected at design time because their performance is not known at that time.

(2)workflow optimisation by selecting optimal web services at run-time and integrating dynamic selection of web service into workflow

(2) fault-tolerance by trying a set of candidates of services

(3) Logging data for analysis of workflow results

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Introduction-- Issues of concern

(1) mechanisms to discover, select and invoke Web services dynamically

(2) mechanisms to optimize workflow by integrating the selection of service into workflow

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Framework --Architecture of dynamic Web services selection for workflow optimisation

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Discovery Service

History Database

Registry (UDDI)

Monitoring Tool

Optimization Service

Proxy Service

Monitor service

Framework --Message sequence of workflow incorporating dynamic Web Service selection

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Optimisation Service

5. List of services

6. Selected service

Workflow script

Workflow deploy

XSLT converter

2. Dynamic invocation through proxy

9. Result through proxy

3. Service query

4. List of services

7. Invoke service

8. Result

Discovery Service

Proxy Service

1. Request 2A. Direct invocation

3A. Direct result

10. Result

Web serviceWorkflow

engineWOSE client

Framework– proxy as adaptor of dynamic selected service

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Service A

Proxy service

Service C

Service B1

Service B2

Service B3

Service B4

Service B5

Framework– proxy service

• Proxy service

• Discovery service

• Optimisation service

• monitor service

• Dynamic invocation service

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Framework– proxy service interface

<wsdl:message name ="ServiceProxyResponse"> <wsdl:part name ="ServiceProxyReturn" type="xsd:string" /> </wsdl:message><wsdl:message name = "ServiceProxyRequest">  <wsdl:part name ="servicemeta“ type="xsd:string"/>   <wsdl:part name ="querymethod" type="xsd:string" /> <wsdl:part nam =" optimizationMETA " type="xsd:string"/>   <wsdl:part name ="optimizationMode" type="xsd:string“/>   <wsdl:part name ="operation" type="xsd:string" />   <wsdl:part name ="parameters“ type="xsd:string" /> </wsdl:message>

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Framework– fault-tolerance and logging

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Public String ServiceProxy(…){ Set values of uddiregistries; Servicelist = discoveryService(… ); While (true) { Service= Optimizationservice(Servicelist); If result =dynamicInvoke(service) fails{ Updates fail-timestamp in Database; Logging; } else { Update average_response_time in database; Logging; Stop; } } Return result; }

Framework– discovery service interface

<wsdl:message name="ServiceDiscoveryResponse"> <wsdl:part name="ServiceDiscoveryReturn" type="xsd:string" /> </wsdl:message> <wsdl:message name="ServiceDiscoveryRequest">  <wsdl:part name="servicemeta" type="xsd:string" />   <wsdl:part name="querymethod" type="xsd:string" />   <wsdl:part name="uddiregistries" type="xsd:string" /> </wsdl:message>

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Function: From UDDI registries to get list of semantic equal services

Framework– discovery methods

Public string ServiceDiscovery (String servicemeta, querymethod, String uddiregistries){Switch querymethod Case byNAME Look up the matched service name in uddiregistry(ies) Case byMETA Look up the matched metadata in the description entity of businessService entity of uddiregistry(ies). Case byONTOLOGY Look up the URL of semantic definition XML File and matchmake the semantically equivalent service. }

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Framework– discovery by name

•Typically used where services are registered by the same business entity but with different access points .

•No extensions are needed to the information contained in the UDDI registry

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Framework– discovery by metadata UDDI extensions

The byMETA method would typically be used where all service providers conform to a particular metadata specification, and have the ability to publish their own services in the UDDI registries.

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Framework– discovery by metadata UDDI extensions

<businessService serviceKey =”37B49950-90A0-11D9-9950- BB91FEE6D433” businessKey = “5D4F01A0-8FE2-11D9-81A0-832EB7272640” > <name>blastallservice</name>  <description> <wosemeta serviceName= “blastallservice" serviceID="1239-3514-6196-8373"/> </wosemeta> </description>  <description> <wosemeta operationName =“serviceblastall" operationID="1351-3612-7812-9156"> <inputype>string</inputtype> <outputtype>string</outputtype> </wosemeta> </description> … </businessService>

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Framework– discovery by ontology

The byONTOLOGY method is used to query all semantically equivalent services by semantic matchmaking. This would typically be used where there are many service providers who publish the services according to the schema encoded in a service ontology. The service providers are loosely connected or without any relationship.

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Framework– discovery by ontology UDDI extensions

<<businessService serviceKey =”14E69DE0-D28D-11D90-80990AF8150A” businessKey = “7D92E5E0-D1C2-11D9-A5E0-CF2D2BB38AE7” > <name>blastallservice</name>   <description> <woseOntology> http://131.251.47.147:8080/axis/blastall.xml </woseOntology> </description> … </businessService>

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Framework– optimisation service interface

<wsdl:message name="ServiceOptimizationRequest">  <wsdl:part name="serviceURL" type="xsd:string" />   <wsdl:part name="optimizationMode" type="xsd:string" />   <wsdl:part name="optimizationMETA" type="xsd:string" /> </wsdl:message><wsdl:message name="ServiceOptimizationResponse">  <wsdl:part name="ServiceOptimizationReturn" type="xsd:string" /> </wsdl:message>

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Function: selecting the optimal service from the list of semantically equivalent services based on the criteria for optimization.

Framework– optimisation service uddi extensions

<wsdl:message name="ServiceOptimizationRequest">  <wsdl:part name="serviceURL" type="xsd:string" />   <wsdl:part name="optimizationMode" type="xsd:string" />   <wsdl:part name="optimizationMETA" type="xsd:string" /> </wsdl:message><wsdl:message name="ServiceOptimizationResponse">  <wsdl:part name="ServiceOptimizationReturn" type="xsd:string" /> </wsdl:message>

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Framework– monitor service interface

- <wsdl:message name="servicemonitorRequest">  <wsdl:part name="monitorType" type="xsd:string" />   </wsdl:message>- <wsdl:message name="servicemonitorResponse">  <wsdl:part name="servicemonitorReturn" type="xsd:string" />   </wsdl:message>

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Function: Get CPU load and CPU speed of the computer

Framework– optimisation criteria

- performance factor= (1- CPU load)*CPU_speed/1000

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Framework– optimisation service

-Performance {-While ( service in servicelist)-{ - performance_factor= monitorservice(); if (performance_factor_max< performance_factor) performance_factor_max = performance_factor; } return service location with max performance_factor}

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Framework– optimisation modes

Public string ServiceOptimization (String serviceURL, String optimizationMode, String optimizationMETA){ Swith optimizationMode Case byPERFORMANCE Look up real-time computer load,etc. and history data. Case byTRUST Look up the trustworthiness of the services. Case byPersonalization Look up the user defined set of criteria }

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Implementation– environment

Operation systems: linux, windowsWeb service container: Tomcat + AXISWorkflow engine: ActiveBEPLWorkflow languages: SCUFL, BPEL4WSDatabase: mySQLUDDI: JUDDI at Welsh e-Science CentreMachines: ygrid01, ygird01, ygrid03,ygrid04,ygrid05,ygrid06,(linux) desktop linux, laptop windows

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Implementation – example

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Implementation– request

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Implementation– result

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Implementation– monitor logging data

CCGrid2005 Wip section12 May, 2005

Implementation– proxy service logging data

CCGrid2005 Wip section12 May, 2005

Conclusion

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1. Present framework for dynamic web service selection within a workflow session

2. Proxy service as adaptor of dynamic selected service

3. Strategy for discovering service by UDDI extensions.

4. Performance service selects optimal service among services by getting real-time data with monitoring service

5. Implementation of the framework

Future work

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1. Optimisation model 2. Discovery service by ontology

method

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Thanks

Questions?