web services choreography description language (ws-cdl)

Model Transformations for Business Process Analysis and Execution

Marlon Dumas

University of Tartu

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Business Process Management (BPM)

Collection of methods and techniques to design, analyze, execute and monitor business operations involving humans, software, information and physical artifacts using process models.

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OK, so what is a process model?

• Collection of inter-dependent activities whose collective performance is intended to achieve a goal such as delivering a product or a service.

• E,g. order-to-cash, procure-to-pay, issue-to-resolution• Animated example

Check Completeness

ObtainAdditional

Information

Check Credit History

Check Income Source(s)

Credit CardApplication

Assess Application

Make Credit Offer

Notify Rejection

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Process models serve many purposes…

ProcessDocumentation

WorkflowManagement

EnterpriseArchitecture

DocumentManagement

KnowledgeManagement

ProcessImprovement

Process CostAnalysis / Simulation

EnterpriseSystems

Compliance /Risk Management

SoftwareEvaluation/Selection

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… they have many faces

Abstract Models

EPC, BPMN

Communication, simulation, activity-

based costing…

ProcessImplementation

ProcessAnalysis & Design

Process Enactment & Monitoring

Process Evaluation

“TO BE”Process Models

Exe

cuta

ble

P

roce

ss M

od

els

Mea

sure

s fo

r Im

pro

vem

ent

Process Metrics

OrganizationalAnalysis

Tar

get V

alue

s

“AS IS”Process Models

Detailed Models

BPEL, State Machines…

Data types, conditions, data mappings, fault

handling…

Integration, testing, deployment…

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…and can be seen from many perspectives

• Control-flow• Data• Resource• Operational

Sound design

Dialog premix FX premix

Music designComposer

Sound Designer

Editor

V

V

Temp picture cut

Temp picture cut

V

V

V

V

Temp music output

Temp sound output

Effect cues Dialog cues Music cues

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Many in one, or one in many?

“The thing can be many in one sense, but also can be one in another sense.”

Imam Ghazali

Revival of Religious Sciences

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Process Modelling:Dealing with Multiplicity

• Multiple modelling languages (meta-models)• Multiple modelling viewpoints

– Control-flow view vs. data view– Public views (protocols) vs. private views

• Multiple abstraction levels– High-level: tasks, performance metrics...– Low-level: data transformations, application bindings...

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Process Modelling Notations

• Business Process Modelling Notation (BPMN)• Event-driven Process Chains (EPC)• Business Process Execution Language (BPEL)• State machines and variants (e.g. IBM Business

State Machine, WWF)• Petri nets (and variants, e.g. YAWL)

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Model transformations

• BPMN-to-BPEL– Purpose: Transform models produced by analysts into

models for developers (and vice-versa)– Commonly supported in commercial tool, but in a limited

manner

• BPEL-to-Petri nets– For analysis & verification

• BPMN-to-Petri nets– For analysis & verification (e.g. deadlock-freeness)

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BPMN from 10 000 miles…

Event Task Flow Gateway

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BPMN: A more detailed view

Start EventIntermediate

Message EventIntermediate Timer Event

Task Parallel Fork Gateway

Parallel Join Gateway

End Terminate EventEnd Event

Flow Event-based Decision Gateway

receive

Merge Gateway

Data-based Decision Gateway

c

~c

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Quick BPMN example

Check stock availability

Reject order

Confirm order

Send invoice

Ship goods

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BPEL from 10 000 miles

• Basic activities: <assign>, <invoke>, <receive>• Sequential flow: <sequence>, <while>, <switch>• Block-structured parallel flow: <flow>• Graph-oriented (parallel) flow: <link> **• Event-action rules: <onEvent> **• Other constructs not relevant to this talk…

** Only partially supported by some tools

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A quick BPEL example

<sequence> <invoke “check stock availability” …/> <switch (…) …/> <case “reject”> <invoke “order rejection” …/> </case> <otherwise> <sequence> <invoke “order acceptance” … /> <flow> <invoke “invoicing” … /> <invoke “ship goods” … /> </flow> </sequence> </otherwise> </switch> </sequence>

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BPMN-to-BPEL: Some monsters!

Bounded multiple-instance task (D)

Unstructured loop

LivelockUnbounded multiple-instance tasks (C)

A B C D

A B C D

A D

A

B

C

D

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BPMN-to-BPEL (from 10 000 miles)

Repeat until reduction to a single node

1. Identify a structured & quasi-structured SESE region Fold into a BPEL structured activity

2. Identify irreducible SESE regions without parallelism Apply GotoWhile transformations, repeat from 1

3. Identify acyclic fragments with concurrency Fold into a BPEL activity with control links

4. Identify minimal unstructured components BPEL event handlers

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BPMN-BPEL: Structured Components

( a ) SEQUENCE-component

( b ) FLOW-component

<sequence> <invoke name="t1"/> <receive name="e1"/> . . . <invoke name="tn"/></sequence>

tc

<flow> <invoke name="t1"/> <wait name="e2"/> . . . <invoke name="tn"/></flow>

tc

t1

e1

tn

t1

tn

e2

C

C

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( e ) WHILE-component

( f ) REPEAT-component

<while condition="c1"> <invoke name="t1"/></while>

tc

<sequence> <invoke name="t1"/> <while condition="c1"> <invoke name="t1"/> </while></sequence>

tc

c1

~c1

t1C

c1

~c1t1

C

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( c ) SWITCH-component

( d ) PICK-component

<switch> <case condition="c1"> <invoke name="t1"/> </case> <case condition="c2"> <receive name="e1"/> </case> . . . <otherwise> <empty/> </otherwise></switch>

tc

tc

<pick> <onMessage name="e1"/> <invoke name="t1"/> </onMessage> <onAlarm name="e2"> <empty/> </onAlarm> . . . <onMessage name="tr"> <invoke name="tn"/> </onMessage></pick>

tn

t1

tr(receive)

e1

e2

C

t1

c2

default

c1

e1

C

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Example: Only Structured Components

Check stock availability

Reject order

Confirm order

Send invoice

Ship goods

Flow-component

Switch-component

Sequence-component

Sequence-component

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BPMN-to-BPEL: Acyclic component

T1

T2

T3

T4

T1 T3

T2 T4

Flow-component

AND

BPMN BPEL

Proposition: Every acyclic BPMN component with a single entry point and a single exit point that is 1-safe and sound can be mapped to a BPEL Flow with links

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ExampleStructured+Acyclic Components

a2

C1

f2

f3

m4

UBL

receive EDI 856 (ASN)

receive EDI 810 (Invoice)

receive despatch-advice

receive invoice

EDI

sendpayment-request

send fulfillment-notice

a1

a4

a3

a5

a6

d1m5

j6

tc1 send fulfillment-notice

a6C2

tc2

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Minimizing the use of control links

a1

a3

a2

a5

a4

a6

a7

a8

fc

jcg2

g1

g3

g4

g5

t1

a5

a7

t2

t3

g4

jc

fc

[a3, a4]

[a1, a2]

[a6, a8]

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For the rest…

• Identify a minimal SESE region that is neither structured nor acyclic

• For each action in the component, retrieve:– All actions that immediately precede it– All actions that immediately follow it

• For each action, code the following behaviour using event-action rules:– Wait for a suitable combination of predecessors to

complete– Perform action– Notify completion to all successors

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BPEL-to-Petri netApplication to Conformance Checking

ServicesServicesabstractBPEL

process

Petri netmodel

SOAPMessages

Event Log

Services

Monitoring /Correlation

Conformance?

ConformanceChecking!

Translation

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From BPEL to WF-nets

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Petri net-based Conformance Checking

Objectives:– quantitatively measure conformance– locate deviations

Conformance?

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Conformance Checking – Fitness

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Conformance Checking – Fitness

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Measuring fitness: Log replay analysis

missing tokensremaining tokens

= 0= 1

consumed tokensproduced tokens

= 0= 0

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= 1= 2

= 0= 0



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= 2= 4

= 0= 0



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= 3= 5

= 0= 0



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= 5= 6

= 0= 0



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= 6= 7

= 0= 0



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= 7= 7

= 0= 0



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= 9= 9

= 0= 0



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= 9= 9

= 0= 0



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= 0= 1

= 0= 0



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= 1= 2

= 0= 0



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= 2= 4

= 1= 0



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= 3= 5

= 1= 0



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= 4= 6

= 1= 0



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= 6= 7

= 1= 0



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= 7= 8

= 1= 0



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= 8= 8

= 1= 1



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= 8= 8

= 1= 1



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f = 1.0 f ≈ 0.540f ≈ 0.955

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Conformance Checking - Appropriateness

100 % fitnessbut not sufficiently specific from behavioral point of view.

100 % fitnessbut not represented instructurally suitable way.

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Ongoing work

• Reversible BPMN ↔ BPEL transformation• Two-way transformation: BPEL ↔ FSM

– Application to automated service composition– BPEL FSM not too difficult – FSM BPEL more exciting, e.g.

A

B

B

A

A

B

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References

web services choreography description language (ws-cdl)

Documents

consumed tokens

bpel flow

bpel activity

bpel structured activity

business process analysis

bpel purpose

analysis verification

bpmn communication