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An Execution Engine for Semantic
Business Processes
Tammo van Lessen1, Jörg Nitzsche1, Marin Dimitrov2, Mihail Konstantinov2,
Dimka Karastoyanova1, Luchesar Cekov2, Frank Leymann1
1Institute of Architecture of Application Systems (IAAS), University of Stuttgart, Germany
2Ontotext Lab. / Sirma Group, Sofia, Bulgaria
tammo.van.lessen@informatik.uni-stuttgart.de

The Talk Today
Motivation and Introduction
Web Services
Web Service Composition
Semantic Web Services
BPEL for Semantic Web Services
Service Interaction Scenarios
Execution Engine for SBP
Architecture
Implementation
Conclusions
© Tammo van Lessen 2

Web Services and Compositions
Workflows
Control logic,
business functions
BPEL - de facto
standard for WS
Collect credit Accept
compositions information Assess Risk credit
Risk=‘low’
All functions amount >= € 1Mill
R
are WSs
is
amo
k
=‘
unt Reject
hi
< € 1M
gh
ill credit
Interface
’
= port type Request
approval
Method
= operation messages
Input/output data operation
= messages
port type
Loose Coupling? Web service Web service Web service
© Tammo van Lessen 3

Web Services and Semantics
Web Service interfaces
Describe messages a service consumes and produces
Syntactic information
No information about their functionality in terms of semantics
hard coding, violation of the loose coupling principle
Semantic Web Service technologies
A layer on top of WSs
WSMO: “goals” and “web services” which define capabilities
(PPAE), choreography and orchestration
OWL-S: profile (IOPE), process, grounding
Currently, both depend on WSs
Service compositions and semantics:
Semantic WSs are used to improve flexibility and reusability of
applications.
© Tammo van Lessen 4

Semantic Discovery with WSMO
© Tammo van Lessen 5

BPEL for Semantic Web Services (BPEL4SWS)
BPELlight
Extension/Restriction of BPEL 2.0
Removes dependencies on WSDL.
Describes Message Exchanges.
Independent of any IDL.
Grouping Activities to
Conversations, Conversations to
Partners
“Grounding” to Services is done
during deployment.
BPEL4SWS
Defines such a “Grounding” for Semantic Web Services.
Introduces an activity to perform data mediation
Proposes an API for SWS middleware to support long running
service interactions.
Uses SA-WSDL for Lifting and Lowering.
© Tammo van Lessen 6

Service Interaction Scenarios
BPEL4SWS processes are rendered as Web Services
Synchronous Invocation of a process
WSMO Web Service
Capabilities
Choreography
grounding
act=op
SWS
Repository
…
act=op
Semantic Service Bus
Synchronous Invocation WSMO Goal
Capabilities
of a (Semantic) Service Choreography
1
…
2 context
3
…
BPEL4SWS process Semantic Service Bus
© Tammo van Lessen 7

Service Interaction Scenarios (2)
Asynchronous Invocation of a process
WSMO Web Service
Capabilities
Choreography
grounding
act=op
SWS
Repository
…
act=op
BPEL4SWS process Semantic Service Bus
WSMO Goal
Asynchronous Invocation Capabilities
Choreography
of a (Semantic) Service 1
grounding
2 context
3
…
act=op 4
BPEL4SWS process Semantic Service Bus
© Tammo van Lessen 8

Semantic BPEL Engine – Architecture
Administration Module
Navigator
Integration Layer
Mediator
Deployment
Component
Reasoner
Lifting &
Lowering
Runtime Build Time
Data Data
© Tammo van Lessen 9

Implementation
Apache Ode as code base
Focus on WSMO/WSMX
Which extension have been done?
BPEL 2.0 Extensibility
Parser, Compiler, internal object model
BPELlight interaction activity
Notion of <conversation>, <partner>
Grounding to WSMO/X
Invocation of WSMO Web services
(Currently only request-response)
“Dualism” of Variable Values
Lifting and Lowering, usage of SA-WSDL
Semantic Assign – Data Mediation
<mediate> as extension assign operation
Utilizes a Reasoner to transform instance data from one ontology to
another.
Monitoring and Event Logging
Execution Events are serialized instances of an Event Ontology
(EVO)
© Tammo van Lessen 10

Summary
Semantic Web Services improve flexibility and
reusability by describing IOPEs.
BPELlight removes the impedance mismatch
between “message orientation” and “interface
orientation”
BPEL4SWS combines both.
Prototypical implementation available.
Still a long way to go…
“Conversational” Interaction Scenarios.
Using semantically enriched log data to improve
Business Activity Monitoring (BAM)
© Tammo van Lessen 11

End of Document

Selected References
Nitzsche, J., van Lessen, T., Karastoyanova, D., Leymann, F.: BPELlight. In:
5th International Conference on Business Process Management (BPM).
(2007) Brisbane, Australia. http://tinyurl.com/ypzahn
Nitzsche, J., van Lessen, T., Karastoyanova, D., Leymann, F.: BPEL for
Semantic Web Services. In: Proceedings of the 3rd International Workshop
on Agents and Web Services in Distributed Environments (AWeSome’07).
© Tammo van Lessen 13