Toward Semantic Web E-Commerce

Massimo Paolucci, Katia Sycara, Takuya Nishimura, Naveen Srinivasan

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 Amazon’s Web

service– Performance evaluation

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

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

Web Services Interaction

• Provider publishes – Process Model – Grounding, WSDL

• Requester uses them to initiate the interaction with the provider

Provider Requester

ProcessModel

Grounding

WSDL

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

Operationally

• Process Model describes a workflow – Atomic Processes– Composite Processes

• Sequence, Split&joint

• Conditionals, Non-deterministic choices

• Loops

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

Process Model Execution RulesBased on formal execution semantics (Ankolekar et al 2002)

executed(atomic(Process)) executedGrounding(Process)

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(List))), 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))

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

Transforming XSD to DAML

Book

author

title

publisher

price

Bookauthor

Personnameage

titlepublisher

Companynameaddress

price

XSD DAML

DAML-S Virtual Machine

SOAP

Provider Web Service Description

WSDL

DAML-SProcessModel

DAML-SGround

ing

DAML Inference Engine

Jess

DAML Jess KB

Process Model Execution Rules

Grounding Execution Rules

DAML-S Processor

Axis’s Web Service Invocation Framework

DAMLSWebServiceInvoker

Webservice Invocation

Web Services

Jena

APPLICATION

Requester

DAML-S VM

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

DAMLzon: DAML-S for Amazon.com

• WSDL2DAML-S used to generate DAML-S for Amazon’s Web Service

• DAML-S VM used to interact with Amazon Web service

Process Model for Amazon.com

Book SearchBook SearchReserve BookReserve Book

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

WSDL2DAML-S<wsdl>

</wsdl>

<portType>

</portType>

<operation>

</operation>

<input></input>

<output></output>

<fault></fault>

<damls>

</damls>

<ProcessModel>

</ProcessModel>

<AtomicProcess>

</ AtomicProcess >

<inputs>

</inputs>

<outputs>

</outputs>

Example WSDL2DAML-S

• Atomic Processes are generated automatically

• Need to be specified– Composite Processes

– mapping XSD to DAML

Process Model for Amazon.com

Generated AutomaticallyGenerated Automatically

To Be SpecifiedTo Be Specified

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

browsing+reserving task• Analyzed distribution of time

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

0

5

10

15

20

25

30

35

40

45

1500 2000 2500 3000 3500 4000 4500 5000 5500 >5500

Amazon Client

DAML-S Client

Time required by DAML-S VM

Time required for DataTransformation

Amazon Invocation Time

Results Experiment 2

• DAML-S VM client on browsing+reserving task

– No client for Browsing+Reserving 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

Time of

DAML-S VM

Time of data transform.

Invocation Time

Averagepercentage

83 3%

156 5%

279792%

Strd dev 107 146 1314

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