correctness ensuring process configuration: an approach based on partner synthesis
DESCRIPTION
held by Wil van der Aalst at the BPM 2010 conference in Hoboken, NY.TRANSCRIPT
Correctness Ensuring Process Configuration:An Approach Based on Partner SynthesisWil van der Aalst (TU/e, QUT)Niels Lohmann (U-Rostock, TU/e)Marcello La Rosa (QUT)Jingxin Xu (QUT)
The need for configurable process models: CoSeLoG project
PAGE 1+/- 430 Dutch municipalities
The need for configurable process models: Suncorp case
PAGE 2
End to end process has between 250-1000 process steps
Sources: Guidewire reference models, GIO CISSS Project, CI US&S P4PI Project
Product Dev
• 25+ steps
Sales
• 50+ steps
Service
• 75+ steps
Claims
• 100+ steps
30variations
500steps
Home
Motor
Commercial
Liability
CTP / WC
Two variants of the same process …
PAGE 3
Variation points
PAGE 4
Action
Blocking
Activating
HidingBlocking
Activate
Hide/skip
Block
Configuration = limiting behavior !
Correctness of configurations
• Question 1: Is a particular configuration correct?
• Question 2:Is there a correct configuration?
• Question 3: How to characterize the set of all correct configurations?
• Question 4:How to auto-complete a configuration?
PAGE 5
Configurable Model + Configuration = Configured model
+ =
Can t3 be blocked?
PAGE 6
pI
p5
t7
p6
t8
pO
t2
p3
t1
p2
t4t5
p4
t6
p7
pI
p5
t7
p6
t8
pO
t2
p3
t1
p2
t4t5
p4
t6t3
p7
XOR-join
XOR-split
AND-join
AND-split
Flow
Place
Transition
Token
Block t1 and hide t3 ?
PAGE 7
p2
p3
p5
p8
t3
t1 t2
t4
t6
Prepare Travel Form(Secretary)
Prepare Travel Form(Employee)
ApproveTravel Form
(Admin)
RejectTravel Form
(Admin)
Submit Travel Form for Approval (Employee)
Request for change(Admin)
t7Check & Update Travel Form(Employee)
Arrange travel insurance (Employee)
p4
t5 τ
p6
p7
t9t8
p1
XOR-join
XOR-split
AND-join
AND-split
Flow
Place
Transition
Token
p2
p3
p5
p8
t3
t2
t4
t6
ApproveTravel Form
(Admin)
RejectTravel Form
(Admin)
Submit Travel Form for Approval (Employee)
Request for change(Admin)
t7Check & Update Travel Form(Employee)
p4
t5 τ
p6
p7
t9t8
τ
p1Prepare Travel Form(Employee
Block t4 also?
PAGE 8
p2
p3
p5
p8
t3
t1 t2
t4
t6
Prepare Travel Form(Secretary)
Prepare Travel Form(Employee)
ApproveTravel Form
(Admin)
RejectTravel Form
(Admin)
Submit Travel Form for Approval (Employee)
Request for change(Admin)
t7Check & Update Travel Form(Employee)
Arrange travel insurance (Employee)
p4
t5 τ
p6
p7
t9t8
p1
XOR-join
XOR-split
AND-join
AND-split
Flow
Place
Transition
Token
p2
p3
p5
p8
t3
t2
t6
Prepare Travel Form(Employee
ApproveTravel Form
(Admin)
RejectTravel Form
(Admin)
Submit Travel Form for Approval (Employee)
Request for change(Admin)
t7
p4
t5 τ
p6
p7
t9t8
τ
p1
Existing approaches
• Most approaches only consider the syntactical issues or simply create the configured model and analyze it (i.e., trail and error).
• Our earlier approach using a SAT solver is an exception to this rule, but is limited to free-choice WF-nets.
PAGE 9
W.M.P. van der Aalst, M. Dumas, F. Gottschalk, A.H.M. ter Hofstede, M. La Rosa, J. Mendling, Preserving Correctness During Business Process Model Configuration. In Formal Aspects of Computing (FACS). Vol. 22 No. 3-4, 2010.
New approach
• Based on partner synthesis developed in the Rostock group.
• Implemented in C-YAWL using Wendy.
• Advantages:1. No syntactical restrictions (i.e. beyond WF-nets
and free-choice).2. Complete characterization of all correct
configurations at design time: the so-called configuration guideline.
3. Computation time is moved from configuration time to design time.
PAGE 10
Open nets and weak termination
Open net:• Labeled Petri net without any
syntactical restrictions.• Special label:• Set of final markings, in this case
[p4].
Correctness notion:• weak termination: it is always
possible to reach a final marking (weaker than classical soundness)
PAGE 11
τ
Composition of open nets
PAGE 12
t11 t12 t21xy x
τ t14t13
t15
z
z
t22 z
p11
p12
p13
p14
p21
p22
p23
Ω ={[p14]} Ω ={[p23]}
(t12,t21)
(t14,t22)t13
(t15,t22)
p11
p12
p13
p14
p22
p23
τ
τ τ
τ
Ω ={[p14,p23]}
p21
=
Controllability
• An open net is controllable if there exists another open net such that their composition is weakly terminating.
• An open net is called a partner of another open net if their composition is weakly terminating.
• A controllable open net has at least one partner.• There are efficient techniques to check controllability
and to synthesize partners.[Karsten Wolf. Does My Service Have Partners?. T. Petri Nets and Other Models of Concurrency 2: 152-171 (2009)]
• These are implemented in Wendy. [Niels Lohmann, Daniela Weinberg. Wendy: A Tool to Synthesize Partners for Services. Petri Nets 2010: 297-307.]
PAGE 13
Controllability
PAGE 14
t11 t12 xy
τ t14t13 z
p11
p12
p13
Ω ={[p13]}
p14 = weakly terminating
partner??
Idea: good configuration = partner!
Configurable interface (allow by default)
PAGE 15
PAGE 16
Configurable interface (block by default)
PAGE 16
Configuration guideline (allow by default)
PAGE 17
CG
PAGE 18
Configurable interface (block by default)
PAGE 18CG
Configuration guideline (allow by default)
PAGE 19
CG
Configuration guideline (allow by default)
PAGE 20
CG
PAGE 21
Configuration guideline (allow by default)
CG
Configuration guideline (allow by default)
PAGE 22
CG
Tool support
• YAWL editor− Creating C-YAWL models− Configuring C-YAWL models− Verification and auto-completion (using SAT solver
and/or Wendy)• YAWL engine• YAWL services
PAGE 23
Mapping(.cmap)
C-EPC model(.epml)
ConfiguredC-EPC (.epml)
EPC(.epml)
Questionnaire Model (.qml)
ConfiguredC-YAWL (.yawl)
YAWL Engine spec. (.yawl)
C-YAWL model(.yawl)
Quaestio
Mapper ProcessConfigurator
ProcessIndividualizer
Configurationmodel (.cml)
QuestionnaireDesigner
C-YAWL Editor
C-EPC Designer Process Merger
p2
p3
p5
p8
t3
t1 t2
t4
t6
Prepare Travel Form(Secretary)
Prepare Travel Form(Employee)
ApproveTravel Form
(Admin)
RejectTravel Form
(Admin)
Submit Travel Form for Approval (Employee)
Request for change(Admin)
t7Check & Update Travel Form(Employee)
Arrange travel insurance (Employee)
p4
t5 τ
p6
p7
t9t8
p1
C-YAWL
PAGE 24
C-YAWL
PAGE 25
Conclusion
PAGE 26
• New approach for ensuring the correctness of process configurations based on partner synthesis.
• Advantages:1. No syntactical restrictions (i.e. beyond WF-nets and free-
choice).2. Complete characterization of all correct configurations at
design time: the so-called configuration guideline.3. Computation time is moved from configuration time to
design time.• Implemented in C-YAWL using Wendy.
− Complete support for workflow configuration, verification, and enactment.
− Autocomplete, domain knowledge, etc.
More information
• www.processconfiguration.com(various references to configuration literature and a comprehensive toolset)
• www.yawlfoundation.org(YAWL has been extended to support configuration, cf. C-YAWL)
• service-technology.org(paper and tools - including Wendy - related to the analysis of services)
• www.win.tue.nl/coselog(webpage of the CoSeLoG project)
PAGE 27