Bridging the Gap between Workflow and Semanticbased Web services composition

1
Bridging the Gap between Workflow and
Semantic-based Web services composition

• Taha Osman
• Dhavalkumar Thakker
• David Al-Dabass
• School of Computing Informatics
• Nottingham Trent University
• United Kingdom

2
Motivation

• Future is bright for Web Services
• Standardization
• Seamless publication beyond firewalls
• Composition is future boost
• Value-added services
• Application integration EAI, B2B

• Practical adoption yet to gather expected pace
• Complexity and Poor facilitation to service
  participants
• Pragmatic vision for Web services development

3
Outline

• State of Web services technology today
  motivation
• Analysis of current Composition Approaches
  Workflow management vs. semantic approach
• Bridging the gap between composition techniques,
  a hybrid approach
• Domains of homogenous services, alleviating
  composition and participation burden
• Framework components
• Specification of domain of services
• Membership verification
• Dynamic pool of interchangeable Web services
• Conclusions

4
Current Composition Approaches

• Workflow-based
• Preferred by Industry
• Builds on top of workflow management theory
• Possess features specific to business processes
• Maturity ? RAD support Oracle BPEL Process
  Manager, BPWS4J
• Practicality of use comes at the price of
  flexibility in service selection and flow
  management
• Semantic Approaches
• The Semantic Web vision is to extend
  human-oriented application interfaces to software
  programmes
• Intelligent matchmaking
• Software agent - based automation of service
  composition
• High development complexity and heterogeneity of
  proposed solutions desperate constraining
  practical adoption

5
Our Vision

• Bridging the Gap
• Practicality of Workflow-based approaches
• Benefits of Semantic approaches
• What will the hybrid approach will offer?
• Aid service composer in transparent modelling of
  dynamic composition schemes
• Aid service developer in seamless subscription of
  services in the composition process
• The solution is applicable to large number of
  composition problems, where underlying
  composition logic rarely changes.

6
The Workflow-Semantic Hybrid Framework

• Central Idea grouping of homogenous application
  services in a domain participating in the
  composition process
• Adopt the WFM approach (BPEL) to engineer the
  composition of services from several domains.
• Utilise semantics to reconcile discrepancies
  between services belonging to the same domain
  (domain participants)
• Overview of the framework functionality
• Composer builds a generic composition scheme and
  publishes the expected functionalities from
  domain participants
• Provider configures their Web services to
  subscribe to the scheme with minimal effort
• Added benefit of dynamic replacement of services

7
Our Framework architecture

• Framework consists of three components

Domain Service specification
Membership Verification
DPDWS based composition
8
I - Specification of the domain of services
k/2005/ /ac/uk/2005/ onto/travelquery.owlFlightQuery"

/ac/uk/2005/onto/travelquery.owlnoOfAdults" /
rdfabout"http//www.w3.org/2001/XMLSchemaint"/


//ntu.ac.uk/bpel/ travelagency/"
  xmlnsejethttp//travelagent.ntu.ac.uk/ EasyJe
tFlightService  
agent.ntu.ac.uk/ AirLineDomainService"   pes  
type"int"/ nillable"true" type"dateTime"/

ence
targetNamespace"http//ntu.ac.uk/bpel/travelagenc
y/" xmlnstns"http//ntu.ac.uk/bpel/trave
lagency/" xmlnsplnk"http//schemas.xmlso
ap.org/ws/2003/05/partner-link/"
xmlns"http//schemas.xmlsoap.org/wsdl/"
ntu.ac.uk/bpel/travelagency/"
xmlns"http//www.w3.org/2001/XMLSchema"


typeint"/ name"departure-date" type"dateTime"/
type"dateTime"/
ce

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I Domain Service Specification
ntu/ac/uk/2005/EasyJet/easyjet.owl" y  ost/ntu/ac/ uk/2005/ EasyJet/easyjet.owldepar
tureFlightDate"
ntu/ac/uk/2005/onto/travelquery.owldepartur
e-date"

Airline Domain
agent.ntu.ac.uk/ AirLineDomainService" s  
type"int"/ name"departure-date" nillable"true"
type"dateTime"/ name"return-date" type"dateTime"/
e
agent.ntu.ac.uk/ EasyJetFlightService
"    
name"noOfAdults" type"int"/
nillable"true" type"dateTime"/

type"boolean"/
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I - Specification of the domain of services

• Idea of domain of services naturally fits dynamic
  Web services composition model
• Ultimately, subscribing services have to conform
  to certain configuration to be swappable
• Composer is responsible for domain specification
• Industrial standard WS-CDL works on principles of
  orchestration and domains.

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II - Domain Membership Verification
Airline Domain
Easy Jet Service   Store   mismatch1
( FlightQuery
departureFlightDate, FlightQuerydeparture-date)
messageName
getEasyJetFlightsRequest operation
Name/portType CheckReservation/ EasyJetPortType
Namespace
http//travelagent.ntu.ac.uk/EasyJetFlightSer
vice  Create Store   Namespace prefix
ejet Variable1
inputEasyJetAir
getEasyJetFlightsRequest Variable2  
partnerLink name EasyJetPL
partnerLinkType EasyJetWSLink
partnerRole
EasyJetWSProvider
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II - Domain Membership Verification
AirLine Dynamic Pool for Domain-specific Web
services (DPDWS)
13
III - Integration of Domain Services in a Dynamic
pool of Interchanging services
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III - Integration of Domain Services in a Dynamic
pool of Interchanging services

• //ntu.ac.uk/bpel/travelagency/"
•  
• xmlnsejethttp//travelagent.ntu.ac.uk/EasyJetFli
  ghtService
• tEasyJetWSLink" partnerRole"EasyJetWSProvider"/
  
• encyRequestMessage"
• messageType"ejetgetEasyJetFlightsRequest"/
• query"/tnsFlightQuery/tnsdeparture-date"

Add the new service namespace
Add Variables and PartnerLink Details
Build the Process Logic with the new Service
instance
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Replacing WizzAir Service for EasyJet (namespace)
//ntu.ac.uk/bpel/travelagency/"   xmlnswizzairh
ttp//travelagent.ntu.ac.uk/WizzAirFlightService

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Replacing WizzAir Service for EasyJet (Partner
link and variables)
//ntu.ac.uk/bpel/travelagency/"   xmlnswizzairh
ttp//travelagent.ntu.ac.uk/WizzAirFlightService
partnerLinkType"wizzAir WizzAirWSLink
partnerRole"WizzAirWSProvider"/ messageType"tnstravelagencyRequestMessage"
getWizzAirFlightsRequest"
17
Replacing WizzAir Service for EasyJet (the
process logic)
//ntu.ac.uk/bpel/travelagency/"   xmlnswizzairh
ttp//travelagent.ntu.ac.uk/WizzAirFlightService
partnerLinkType"wizzAir WizzAirWSLink
partnerRole"WizzAirWSProvider"/ messageType"tnstravelagencyRequestMessage"
getWizzAirFlightsRequest" n name"assign-deptdate" variable"input" part"payload"
query"/tnsFlightQuery/tnsdeparture-date"
part"pQuery" query"/wizzairFlightQuery/departur
e-date"/ name"RetrievePriceQuoteSequence" name partnerLink"WizzAirPL" portType"wizzairWiz
zAirPortType operation"checkReservation"
inputVariable"inputWizzAir"
outputVariable"outputWizzAir"/
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Conclusions

• Improving the appeal of Web services composition
  to businesses requires the consideration of
  reducing the complexity of knowledge and effort
  required from service providers and composers
• Our contribution marries the benefit of
  practicality of use and adoption popularity of
  workflow-based (BPEL-based) composition, with the
  advantage of using semantic description to aid
  the composition participants in subscribing
  dynamically interchangeable Web services to the
  composition process
• Future work will extend to the intelligent
  discovery and interoperability of the composition
  framework based on the OWL-S standard