Toward Semantic Web E-Commerce

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Toward Semantic Web E-Commerce

• Massimo Paolucci, Katia Sycara, Takuya Nishimura,
  Naveen Srinivasan

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Overview

• Present DAML-S VM a generic processor for the
  DAML-S Process Model that can be used to interact
  with any DAML-S Web service
• Process Model semantics
• Architecture of the DAML-S VM
• Example of execution using Amazons Web service
• Performance evaluation

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Crucial Problems

• Capability based discovery
• Web services should find each other on the basis
  of what they do
• Semantic interoperation
• Web services understand the information that
  they exchange and use it to solve their problems

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Requirements of Interaction

• Shared Knowledge of interaction protocols
• What information the provider needs
• When does it need it
• Shared understanding of content of messages
• Ontologies that act like dictionaries
• Logic framework for correct interpretation
• Agreement on ports and low level details

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Web Services Interaction
Process Model
Provider
Requester
Grounding
WSDL

• Provider publishes
• Process Model
• Grounding, WSDL
• Requester uses them to initiate the interaction
  with the provider

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Process Model

• Detailed view of the Web Service
• Provides description of how the Web service
  accomplishes its tasks
• Interaction protocol
• Specifies when Web service requires inputs from
  requesters
• Specifies what information (and when) Web service
  sends to the requesters

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Operationally

• Process Model describes a workflow
• Atomic Processes
• Composite Processes
• Sequence, Splitjoint
• Conditionals, Non-deterministic choices
• Loops

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Process

• Processes are defined by
• Inputs that they require
• Outputs that they generate
• Preconditions that should be satisfied for the
  correct execution of the process
• Effects that result from the execution of the
  process

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Process Model Execution Rules

• Based on formal execution semantics (Ankolekar et
  al 2002)
• executed(atomic(Process)) ? executedGrounding(Proc
  ess)
• executed(sequence(Process,List)) ?
• executed(first(List)), executed(sequence(Process,
  rest(List)))
• executed(split(Process,List)) ?
• exec(first(List)), exec(split(Process,rest(List))
  )
• executed(splitJoint(Process,List)) ?
• exec(first(List)), exec(splitJoint(Process,rest(L
  ist))), complete(first(List)),
  complete(splitJoint(Process,rest(List)))
• executed(if(Cond,ThenProcess,ElseProcess)) ?
• ( Cond, executed(ThenProcess) ) XOR
  executed(ElseProcess)
• executed(choice(Process,List)) ?
  executed(oneOf(List))

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Grounding

• Specify mapping to WSDL
• Atomic Processes map to Operations
• Inputs/Outputs described as messages
• Specify XSLT transformations for mapping to and
  from DAML and XSD types

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Transforming XSD to DAML
XSD
DAML

• Book
• author
• title
• publisher
• price

• Book
• author
• Person
• name
• age
• title
• publisher
• Company
• name
• address
• price

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DAML-S Virtual Machine
Web Services
SOAP
Provider Web Service Description
DAML-S VM
Webservice Invocation
Axiss Web Service Invocation Framework
Requester
WSDL
DAMLS WebServiceInvoker
APPLICATION
DAML-S Processor
DAML-S Ground ing
Grounding Execution Rules
Process Model Execution Rules
DAML-S Process Model
DAML Inference Engine
DAML Jess KB
Jess
Jena
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Features DAML-S VM

• DAML-S VM a generic processor for the DAML-S
  Process Model
• It can interact with any DAML-S Web service
• Uses only DAML-S as representation of Web
  services
• Based on the Process Model formal semantics
• Shows how to integrates DAML-S within Web
  services technology such as Axis and WSIF

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DAMLzon DAML-S for Amazon.com

• WSDL2DAML-S used to generate DAML-S for Amazons
  Web Service
• DAML-S VM used to interact with Amazon Web service

Book Search
Reserve Book
Process Model for Amazon.com
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WSDL2DAML-S

• WSDL2DAMLS allows easy translation of WSDL
  documents in DAML-S
• Automatic generation of Grounding
• Partial generation of Process Model and Profile
• Up to 80 of work required to generate a DAML-S
  description is done automatically
• Combined with Java2WSDL to provide Java2DAML-S

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WSDL2DAML-S
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Example WSDL2DAML-S
To Be Specified

• Atomic Processes are generated automatically
• Need to be specified
• Composite Processes
• mapping XSD to DAML

Generated Automatically
Process Model for Amazon.com
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Performance Measures

• We compared the performance of using DAML-S in
  its interaction with Amazon.com
• Two experiments
• Compared Amazon client with DAML-S VM client on
  browsing task
• Used DAML-S VM client on browsingreserving task
• Analyzed distribution of time

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Results Experiment 1

• Compared Amazon client with DAML-S VM client on
  browsing task
• 98 runs total over 4 days in varying load
  conditions
• Results in milliseconds

Amazon Client DAML-S VM
Average execution time 2007 ms (1760 ms) 2021 ms (1861 ms)
Strd Deviation 1134 ms (565 ms) 776 ms (450 ms)
Distribution
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Results Experiment 2
Time of DAML-S VM Time of data transform. Invocation Time
Average percentage 83 3 156 5 2797 92
Strd dev 107 146 1314

• DAML-S VM client on browsingreserving task
• No client for BrowsingReserving provided by
  Amazon
• Analyzed data by computing
• Time required by DAML-S VM to execute Process
  Model
• Time required for data transformation to fit
  Amazon requirements
• Time required to invoke an operation on Amazon
• 98 runs total over 4 days in varying load
  conditions
• Results in milliseconds

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Conclusion

• DAML-SVM is a generic DAML-S port that can be
  used to interact with any Web DAML-S service
• It conforms with the DAML-S semantics
• It is based on DAML inference engine
• The use of DAML-S does not result in a
  performance penalty

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Semantic Web Services

• Semantic Web provides
• Shared ontologies shared dictionaries
• Logic framework to derive consequences from
  knowledge
• Contributions to Web services
• Description of the domain and reasoning tools
• Facilitate Web Services interoperation
• Less ambiguity of XML
• Representation of Web services grounded in their
  domain
• Greater Automation

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Crucial Problems

• Language to describe Web services
• Describe properties of Web Services
• Grounded in the Semantic Web
• Build on Web Services standards
• Capability based discovery
• Web services should find each other on the basis
  of what they do
• Semantic interoperation
• Web services understand the information that
  they exchange and use it to solve their problems

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Solutions

• Language to describe Web services
• DAML-S
• Capability based discovery
• DAML-S Profile
• DAML-S/UDDI Matchmaker
• Semantic interoperation
• DAML-S Process Model
• DAML-S Virtual Machine

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Solutions

• Languages to describe Web services
• DAML-S
• Tools that implement the specifications
• DAML-S/UDDI Matchmaker
• add capability matching to UDDI
• DAML-S Virtual Machine
• use DAML-S and WSDL for Web service invocation

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R
P
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DAML-S/UDDILimitations and Value

• Value
• DAML-S allows capability representation
• DAML-S Matching engine allows matching of
  capabilities
• DAML-S can be used to enable capability matching
  inUDDI
• Limitations
• Matching restricted to I/O should be expanded to
  preconditions and effects
• Tighter integration within UDDI

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from Discovery to Interaction

• Discovery tells which Web services are out there
• Next step is to interact with them

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Assumption

• Suppose that Discovery succeeded and a provider
  has been found
• Next step is to interact with them

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DAML-S

• Loosely speaking

DAML-S Web Services Infrastructure
Discovery Profile UDDI
Choreography Process Model WSCI BPEL4WS
Invocation Grounding WSDL WSDL
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Capability Representation

• DAML-S Profile used to represent capabilities of
  Web services
• Input Output
• Preconditions Effects
• Provenance
• person or entity responsible for the Web service
• Properties
• Security Requirements
• Quality of service

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Capability Matching

• Requester describes its needs as DAML-S Profile
  of ideal Web service to interact with
• Matching Engine find Web service(s) that more
  closely fit the description
• Need of flexible matching

Exact match out(P) out(R) in(P) in(R)
Plug in match out(P) ? out(R) in(P) ?in(R)
Subsumed match out(P) ?out(R) in(P) ? in(R)
Fail otherwise
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DAMLSWithinUDDI

• Use Tmodels to represent DAML-S within UDDI

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Architecture DAML-S/UDDI
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Promise of Semantic Web

• Augment Web services infrastructure with Semantic
  Information
• Automatic Composition of Web services
• Today programmers use WSDL specs to make their
  programs interact with Web services
• Tomorrow (with Semantic Web) programs
  automatically select the Web services they want
  to interoperate and automatically interact with
  them
• The promise greater automatism