Web Service Choreography Configurations for BPMN

Kerstin Pfitzner1, Gero Decker2, Oliver Kopp1, Frank Leymann1

Web Service Choreography Configurations for BPMN

Third International Workshop on Engineering Service-Oriented Applications:Analysis, Design and Composition

WESOA’07 – http://wesoa07.googlepages.com/

Presented by Oliver Kopp © Kerstin Pfitzner, Gero Decker, Oliver Kopp, Frank Leymann 2

Motivation

BPMN

BPEL4Chor

set of abstractBPEL processes

transformation

transformationinstead of manual steps

configurationsneeded

set of executableBPEL processes

executable completion(manual work)


Agenda

Orchestrations and Choreographies

BPEL4ChorExtensions for BPEL to model choreographies

Configurations for BPMN to support modeling BPEL4Chor


Bookshop orchestrationSupplierClient Book shop

send not found

send response

select cheapest supplier

price receivedno price received

update suppliers

data

Not found request

price

De facto standards:BPMN, BPEL


The bookshop choreography - pure BPMNSupplierClient

send price request

Book shop

send not found

send response



update suppliers

data

Not found request

price

calculate price

book not found book found

reply not found

reply

De facto standard:BPMN


Other languages to model choreographies

Interaction model (simplified)

Interconnection model

Let’s Dance,WS-CDLBPEL4Chor

SupplierClient

send price request

Book shop

send not found

send response



update suppliers

data

Not found request

price

calculate price


reply not found

reply

for each element in S (concurrent) (bs)

Response

Supplier(S)

Book shop(bs)

Order

Client(c)

Book shop (bs)

Price Request

Book shop(bs)

Supplier (S)

Offer

Book shop (bs)

Client(c)

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BPEL4Chor


BPEL4Chor

Includes all features of BPEL 2.0, e.g.Event handlerTermination handlerUses abstract BPEL

Plus choreography informationNotion of participantsMultiplicity of participantsParticipant references


BPEL4Chor Participant Behavior Descriptions

<sequence><invoke

wsu:id=“sendPriceRequest” />

<pick><onMessage wsu:id=“receivePrice” />

<onMessagewsu:id=“receiveNotFound” />

</pick></sequence>

Client

send price request

Book shop

send not found

send response



update suppliers

data

Not found request

price


BPEL4Chor Participant Topologies<topology name=“bookshop" …>

<participantTypes><participantType

name=“BookShop" participantBehaviorDescription=“mychor:BookShop" /> <participantType name=“Supplier“ … /> …

</participantTypes>

<participants><participant name=“b"

type=“BookShop" /><participantSet name=“suppliers”

type=“Supplier”<participant name=“currentSupplier” />

</participantSet>…

SupplierClient Book shop


BPEL4Chor Participant Topologies

<messageLinks><messageLinksender=“c“sendActivity=“sendPriceRequest”receiver=“BookShop“receiveActivity=“getOrder”messageName=“order" /> …

</messageLinks>

Client

send price request

Book shop

send not found

send response



update suppliers

data

Not found request

price

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Configurations for BPMN


What is missing in BPMN?

Features of BPEL 2.0Event handlerTermination handler

BPMN: only termination of transactional sub-processes

Certain choreography informationMultiplicity of participantsParticipant references


BPEL basic activities

Basic activities distinguished by marking


BPEL4Chor data types

Rendering of the different variable types of BPEL


Reference passing

There exist only one instance of ZThis instance is created by XThe reference to Z needs to be passed to Y


Pool sets and references

Pool sets contain multiple instances of one participantSender and receiver have to be specified, if there are multiple instances of them


Iteration over a participant set

Specification ofSet to iterate onName of the current participant reference


BPEL handlers

Different handlers distinguished by markingEvent HandlerFault HandlerTermination HandlerCompensation Handler

... ... ...

invokesynch.

...


Bookshop choreography / configured BPMNSupplierClient

send price request

Bookshop

send not found

send not found



update suppliers

data

request price

calculate price


suppliers

currentsupplier

reply not found

reply

not found


Transform configured BPMN to BPEL4Chor

Extending existing transformationOuyang et al.: Pattern-based translation of BPMN process models to BPEL web services

Adopting restrictions:Exclusion of e.g.

Ad-hoc or transactional sub-processesEnd-events with triggersTasks of type user, script, abstract, manual reference, non-typed

Excluded support of arbitrary cyclesBPMN configuration respected in the mapping


Summary

BPEL4Chor as choreography extension of BPELMultiple participants of one type

Configurations of BPMN to fully support modeling of BPEL4ChorOngoing work

Implementation of mapping of configured BPMN to BPEL4ChorInteraction models vs. interconnection models

Future workEvaluation

Web Service Choreography Configurations for BPMN

Technology

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