The document discusses various aspects of service interaction in the context of computer and software systems, including workflow patterns, service choreography, and analysis techniques. It highlights the importance of service interaction patterns and identifies key challenges such as exposing services, service replacement, and integration using adapters. The document also presents a structured outline of the tutorial and provides insights into service mining and process design.

1. Service Interaction:
Patterns, Formalization, and Analysis
9th International School on Formal Methods for the Design of
Computer, Communication and Software Systems: Web
Services (SFM-09:WS), Bertinoro, Italy, June 1-6, 2009.
prof.dr.ir. Wil van der Aalst
www.vdaalst.org
Joint work with Arjan Mooij,
Christian Stahl, and Karsten Wolf

2. BEST: Berlin - Rostock- Eindhoven
Service Technology Program
http://www2.informatik.hu-berlin.de/top/best/
PAGE 1

3. Outline
• Introduction to Service Interaction
• Workflow and Service Interaction Patterns
• Challenging Analysis Questions
• A "Crash Course" in Petri Nets
• Exposing Services
• Replacing and Refining Services
• Integrating Services Using Adapters
• Service Mining
• Conclusion
PAGE 2

4. Introduction to
Service Interaction

5. Service-Orientation: Basic Idea
invoke
service receive service
A B
reply
“buy “sell
service side” side” service
requester provider
PAGE 4

6. Service Networks
service
C
service service
A B
service
D
“buy “sell “buy “sell
service side” side” service side” side” service
requester provider & providers
requestor
PAGE 5

7. Choreography
service choreography service
A D
service service
B C
PAGE 6

8. Orchestration
orchestration service
B
service
service C
A
service
D
PAGE 7

9. Workflow?
workflow in the
classical sense
service
A
PAGE 8

10. Some Terminology
service choreography
service definition
activity
channel
activity
port channel message port
service definition service definition
interface interface
Important assumption: asynchronous communication. PAGE 9

11. Interaction is a source of errors!
PAGE 10

12. p1 p5
place accept
order order
p2 p6
eat cook
food food
p3 p7
pay collect
money money
p4 p8
PAGE 11

13. p1 p5
place accept
order order
p2 p6
eat collect
food food
p3 p7
pay cook
money money
deadlock
p4 p8
PAGE 12

14. restaurant is
"uncontrollable"*
p1 p5
place accept
order order
p2 p6
eat cook
food food
leave p3 p7 get drunk
pay collect
customer is money money *by any service
with only dead
"controllable" but will
p4 p8 final markings
never get any food PAGE 13

15. p1 p5
place accept
order order
p2 p6
eat cook
food food
leave p3 p7 get drunk
pay song song collect
money money
p4 p8
PAGE 14

16. Workflow and Service
Interaction Patterns

17. MS Workflow Foundation Global 360 BPM Suite
YAWL FileNet InConcert
Fujitsu Interstage
Axxerion BWise
Software AG/webMethods
casewise COSA XPDL IBM WebSphere
BPEL
UML ADs Savvion BusinessManager
jBPM BPM|one TIBCO iProcess Suite
BPMN EPCs FlowConnect SAP Workflow
Pegasystems SmartBPM Suite Ensemble
Bizagi TeamWARE Oracle BPEL
Promatis BiZZdesigner
Ultimus BPM Suite PAGE 16

18. Workflow Patterns Initiative
• Started in 1999, joint work TU/e and QUT
• Objectives:
• Identification of workflow modeling scenarios and solutions
• Benchmarking
− Workflow products (MQ/Series Workflow, Staffware, etc)
− Proposed standards for web service composition (BPML, BPEL)
− Process modeling languages (UML, BPMN)
• Foundation for selecting workflow solutions
• Home Page: www.workflowpatterns.com
• Primary publication:
• W.M.P. van der Aalst, A.H.M. ter Hofstede, B. Kiepuszewski, A.P. Barros,
“Workflow Patterns”, Distributed and Parallel Databases 14(3):5-51, 2003.
• Evaluations of commercial offerings, research
prototypes, proposed standards for web
service composition, etc PAGE 17

19. Workflow Patterns Framework
time 2000 2003 Jun 2005 Oct 2005 Sep 2006
Jun 2006
revised
Control-flow P:s 20 Resource P:s - 43 Data P:s - 40 Control-flow P:s 43
Exception P:s
W. van der Aalst N. Russell N. Russell N. Russell
N. Russell
A. ter Hofstede W. van der Aalst A. ter Hofstede A. ter Hofstede
W. van der Aalst
B. Kiepuszewski A. ter Hofstede D. Edmond W. van Hofstede
A. ter der Aalst
A. Barros D. Edmond W. van der Aalst N. Mulyar
The ordering of Resource definition Data representation Exception handling
- 23 new patterns
activities in a & work distribution and handling in a inFormalised in
- a process
process in a process process CPN notation
CoopIS’2000
CAiSE’2005 ER’2005 TR
CAiSE’2006
DAPD’2003
Slides adopted from Nick Russell, et al. PAGE 18

20. Workflow Patterns Framework
time 2000 2003 Jun 2005 Oct 2005
Control-flow P:s 20 Resource P:s - 43 Data P:s - 40 Exc
E COSA Domino Workflow Staffware Staffware Staf
v FLOWer Visual Workflow WebSphere MQ MQSeries We
a Eastman Forte Conductor FLOWer FLOWer FLO
l Meteor MQSeries/Workflow COSA COSA CO
Mobile SAR R/3 Workflow iPlanet iPla
u
I-Flow Verve Workflow
a Staffware Changengine
t InConcert
I
o
n XPDL, BPEL4WS, BPML, BPEL4WS XPDL, BPEL4WS XPD
s WSFL, XLANG, WSCI, UML AD 2.0 UML AD 2.0, BPMN BPE
UML AD 1.4 UML AD 2.0, BPMN BPMN
Language Development: YAWL/newYAWL
PAGE 19

21. Service Interaction Patterns
service choreography
service definition
activity
channel
activity
port channel message port
service definition service definition
interface interface
• Basic Service Interaction Patterns (SIP-1, ... ,SIP-15)
• Correlation Patterns (SIP-16, ... ,SIP-23)
• Anti-Patterns (AP-1, AP-2, and AP-3)
PAGE 20

22. Send Patterns
c1 c1
c1 block send
send c2 c2
p p p
c2 send block
c3 c3
SIP-1 Send pattern SIP-2 Pre-Blocking SIP-3 Post-Blocking
Send pattern Send pattern
PAGE 21

23. Receive Patterns
remove
c1 c1
receive receive
p p
c2 c2
SIP-4 Receive pattern SIP-5 Lossy Receive pattern
PAGE 22

24. Concurrent Send/Receive Patterns
c1 c1
AND-split AND-split
c2 c3 c2 c3
p1 receive1 receive2 p1
send1 send2
p2 c4 c5 p2
c4 c5
AND-join AND-join
c6 c6
SIP-6 Concurrent Send pattern SIP-7 Concurrent Receive pattern
PAGE 23

25. Choice Patterns
c1 c1
send1 send2 p1 receiving1 receiving2 p1
c2 c3 p2 c2 c3 p2
SIP-8 Sending Choice pattern SIP-9 Receiving Choice pattern
c1
internal1 internal2 p1
c2 c3 p2
SIP-10 Internal Choice pattern PAGE 24

26. Choice With a Follow-Up Patterns (1/2)
c1 p1 c1
receive1 receive2 p1
send1 send2 p2
c2 c3 p2
c2 c3
p3 send1 send2 p3
receive1 receive2
p4 c4 p4
c4
SIP-11 Sending Choice SIP-12 Receiving Choice
Receiving Follow-Up pattern Sending Follow-Up pattern
PAGE 25

27. Choice With a Follow-Up Patterns (2/2)
• SIP-13 Sending Choice Sending Follow-Up
• SIP-14 Receiving Choice Receiving Follow-Up, and
• SIP-15 Internal Choice Sending Follow-Up.
See problem?
PAGE 26

28. Anti-Pattern AP-1: Internal Choice Receiving
Follow-Up Anti-Pattern
c1
internal1 internal2
c2 c3
receive1 receive2 p1
c4 p2
PAGE 27

29. Another variant of AP-1
c1
send skip
c2 p1
receive p2
c3
PAGE 28

30. Two Additional Variants of AP-1
p1 p5
place accept
order order
p2 p6
eat cook
food food
leave p3 p7 get drunk
pay collect
money money
p4 p8
PAGE 29

31. Correlation
p1 p5 c1
(me,you)
(from,to,content)
place accept send
order order (me,you)
p2 p6 c2
eat cook
food food c1
p3 p7 (me,you)
(from,to,content)
receive
pay collect (me,you)
money money c2
p4 p8
PAGE 30

32. Correlation Send Patterns
c1 c1
[from:=me] (me,*) [to:=you] (me,you)
(from,*,content) (*,to,content)
send send
(me,*) p p
(me,you)
c2 c2
SIP-16 Leading Correlated SIP-17 Following
Send pattern Correlated Send pattern
PAGE 31

33. Anti-Pattern AP-2:
Uncorrelated Send Anti-Pattern
c1
(me,you)
(*,*,content)
send
(me,you) p
c2
PAGE 32

34. Correlation Receive Patterns (1/2)
c1 c1
[me=to] (me,*) [you=from] (me,you)
(*,to,content) (from,*,content)
receive receive
(me,*) p (me,you) p
c2 c2
SIP-18 Leading Correlated SIP-19 Following Correlated
Receive pattern Receive pattern
PAGE 33

35. Correlation Receive Patterns (2/2)
c1
[me:=new()]
[me=to] (me,*) (from,*,content)
(from,to,content) receive
receive
[you:=from] (me,you) p
[you:=from] (me,you) p
c1
c2
SIP-20 Learning Correlated SIP-21 Creating Correlated
Receive pattern Receive pattern
PAGE 34

36. Anti-Pattern AP-3:
Uncorrelated Receive Anti-Pattern
c1
(me,*)
(from,*,content)
receive
(me,*) p
c2
PAGE 35

37. Composite Correlation Patterns (1/2)
SIP-22 Correlation
[you2:=from1] Swap pattern
[from1:=me1] (me1,*) [me2:=new()]
send1 receive1
(me1,*) (from1,*,content1) (me2,you2)
[me1=to2] [from2:=me2]
[you1:=from2] (from2,to2,content2) [to2:=you2]
receive2 send2
(me1,you1) (me2,*)
[to3:=you1] (*,to3,content3) [me2=to3]
send3 receive3
(me1,you1) (me2,*)
PAGE 36

38. Composite Correlation Patterns (1/2)
SIP-16 Leading Correlated SIP-21 Creating Correlated SIP-22 Correlation
Send pattern Receive pattern Swap pattern
[you2:=from1]
[from1:=me1] (me1,*) [me2:=new()]
send1 receive1
(me1,*) (from1,*,content1) (me2,you2)
SIP-20 Learning Correlated Receive pattern
[me1=to2] [from2:=me2]
[you1:=from2] (from2,to2,content2) [to2:=you2]
receive2 send2
(me1,you1) (me2,*)
[to3:=you1] (*,to3,content3) [me2=to3]
send3 receive3
(me1,you1) (me2,*)
SIP-17 Following SIP-18 Leading Correlated
Correlated Send pattern Receive pattern PAGE 37

39. Composite Correlation Patterns (2/2)
[x=from1]
[from1:=me1] (me1,*) [to1:=y] (me2,*) [me2=to1]
relay1
send1 receive1
(me1,*) (from1,*,content1) (x,y) (*,to1,content1) (me2,*)
db
[me1=to2] (*,to2,content2) (x,y) (from2,*,content2) [from2:=me2]
receive2 send2
relay2
(me1,*) [to2:=x] (me2,*)
[y=from2]
SIP-23 Correlation Broker pattern
PAGE 38

40. Composite Correlation Patterns (2/2)
SIP-16 Leading SIP-19 Following SIP-17 Following SIP-18 Leading Correlated
Correlated Send pattern Correlated Receive pattern Correlated Send pattern Receive pattern
[x=from1]
[from1:=me1] (me1,*) [to1:=y] (me2,*) [me2=to1]
relay1
send1 receive1
(me1,*) (from1,*,content1) (x,y) (*,to1,content1) (me2,*)
db
[me1=to2] (*,to2,content2) (x,y) (from2,*,content2) [from2:=me2]
receive2 send2
relay2
(me1,*) [to2:=x] (me2,*)
[y=from2]
SIP-18 Leading Correlated SIP-17 Following SIP-19 Following SIP-16 Leading Correlated
Receive pattern Correlated Send pattern Correlated Receive pattern Send pattern
SIP-23 Correlation Broker pattern
PAGE 39

41. Recommended Reading (1/2)
• van der Aalst, W., Mooij, A.J., Stahl C., Wolf, K.. Service Interaction:
Patterns, Formalization, and Analysis. In SFM 2009, volume 5569 of Lecture
Notes in Computer Science, pages 42-88. Springer-Verlag, Berlin (2009)
• Barros, A., Dumas, M., ter Hofstede, A.: Service Interaction Patterns. In:
Aalst, W., Benatallah, B., Casati, F. Curbera, F. (eds.) BPM 2005. LNCS,
vol. 3649, pp. 302–318. Springer, Heidelberg (2005)
• Mulyar, N., Aldred, L., van der Aalst, W.: The Conceptualization of a
Configurable Multiparty Multi-message Request-Reply Conversation. In:
Meersman, R., Tari, Z. (eds.) OTM 2007, Part I. LNCS, vol. 4803, pp. 735–
753. Springer, Heidelberg (2007)
• van der Aalst, W., ter Hofstede, A., Kiepuszewski, B., Barros, A.: Workflow
Patterns. Distributed and Parallel Databases 14(1), 5–51 (2003)
• Russell, N., ter Hofstede, A., van der Aalst, W., Mulyar, N.: Workflow
Control-Flow Patterns: A Revised View. BPM Center Report BPM-06-22,
BPMcenter.org (2006)
• Mulyar, N.: Patterns for Process-Aware Information Systems: An Approach
Based on Colored Petri Nets. Ph.D thesis, Eindhoven University of
Technology, Eindhoven (2009)
PAGE 40

42. Recommended Reading (2/2)
• Hohpe, G., Woolf, B.: Enterprise Integration Patterns. Addison-Wesley
Professional, Reading (2003)
• Russell, N., van der Aalst, W., ter Hofstede, A., Edmond, D.: Workflow
Resource Patterns: Identification, Representation and Tool Support. In:
CAiSE 2005. LNCS, vol. 3520, pp. 216–232. Springer, Heidelberg (2005)
• Russell, N., ter Hofstede, A., Edmond, D., van der Aalst, W.: Workflow Data
Patterns: Identification, Representation and Tool Support. In: ER 2005.
LNCS, vol. 3716, pp. 353–368. Springer, Heidelberg (2005)
• Russell, N., van der Aalst, W., ter Hofstede, A.: Workflow Exception
Patterns. In: Dubois, E., Pohl, K. (eds.) CAiSE 2006. LNCS, vol. 4001, pp.
288–302. Springer, Heidelberg (2006)
• Gamma, E., Helm, R., Johnson, R., Vlissides, J.: Design Patterns: Elements
of Reusable Object-Oriented Software. Professional Computing Series.
Addison Wesley, Reading (1995)
• Alexander, C.: A Pattern Language: Towns, Building and Construction.
Oxford University Press, Oxford (1977)
PAGE 41

43. Challenging Analysis
Questions

44. Questions Addressed in this Tutorial
1. Exposing Services
 How to inform others about me such that cooperation
is possible?
 Two approaches: (a) expose own behavior and (b)
provide operating guideline.
2. Replacing and Refining Services
 How to replace or refine a service without introducing
problems?
 Inheritance, accordance, transformation rules, etc.
3. Integrating Services Using Adapters
 How to resolve behavioral incompatibilities?
 Adapter generation.
4. Service Mining
 How to analyze the run-time behavior?
PAGE 43

45. Additional Questions
• Verification (e.g., various types of soundness)
• Controllability (Is there a compatible partner?)
• Instance migration (Can I replace a service at run-
time?)
• Querying software repositories (Is there a service
that ... ?)
• Similarity of services (What is the least incompatible
service? How many edit steps are needed to
transform one into the other?)
• How to generate/compose services to meet specific
requirements and goals?
PAGE 44

46. Design-time analysis of processes
Protos BPMN linear algebraic
analysis techniques
YAWL Flower
Markov chain
Petri net analysis techniques
Staffware
SAP Workflow state-space analysis
techniques
BPEL
simulation
....
PAGE 45

47. From BPEL to Petri Nets and Back
• Feature complete mappings from BPEL to Petri
nets:
• WofBPEL (TU/e & QUT)
• BPEL2oWFN (Rostock & Humboldt)
• Mappings from Petri nets to BPEL:
• WorkflowNet2BPEL4WS (TU/e & Aarhus)
• oWFN2BPEL (Rostock & Humboldt)
• Similar results hold for the BPMN, EPCs, etc.!
• Be critical! Not all reported results exist :-)
PAGE 46

48. Recommended Reading (1/3)
• van der Aalst, W., Mooij, A.J., Stahl C., Wolf, K.. Service Interaction: Patterns,
Formalization, and Analysis. In SFM 2009, volume 5569 of Lecture Notes in Computer
Science, pages 42-88. Springer-Verlag, Berlin (2009)
• van der Aalst, W., Lohmann, N., Massuthe, P., Stahl, C., Wolf, K.: From Public Views to
Private Views: Correctness-by-Design for Services. In: Dumas, M., Heckel, H. (eds.)
WS-FM 2007. LNCS, vol. 4937, pp. 139–153. Springer, Heidelberg (2008)
• Massuthe, P., Reisig, W., Schmidt, K.: An Operating Guideline Approach to the SOA.
Annals of Mathematics, Computing & Teleinformatics 1(3), 35–43 (2005)
• Wolf, K.: Does my service have partners? In: ToPNoC II 2008. LNCS, vol. 5460, pp.
152–171. Springer, Heidelberg (2008)
• Massuthe, P., Reisig, W., Schmidt, K.: An Operating Guideline Approach to the SOA.
In: Proceedings of the 2nd South-East European Workshop on Formal Methods 2005
(SEEFM 2005), Ohrid, Republic of Macedonia (2005)
• van der Aalst, W.M.P. et al.: Life After BPEL? In Formal Techniques for Computer
Systems and Business Processes, LNCS, vol. 3670, pp. 35–50. Springer, Heidelberg
(2005)
• www.service-technology.org
PAGE 47

49. Recommended Reading (2/3)
• Lohmann, N., Massuthe, P., Wolf, K.: Operating guidelines for finite-state
services. In: Kleijn, J., Yakovlev, A. (eds.) ICATPN 2007. LNCS, vol. 4546, pp.
321–341. Springer, Heidelberg (2007)
• Stahl, C., Massuthe, P., Bretschneider, J.: Deciding substitutability of services
with operating guidelines. In: ToPNoC II 2008. LNCS, vol. 5460, pp. 172–191.
Springer, Heidelberg (2008)
• Massuthe, P., Serebrenik, A., Sidorova, N., Wolf, K.: Can I find a partner?
Undecidablity of partner existence for open nets. Information Processing
Letters 108(6), 374–378 (2008)
• van der Aalst, W.M.P., et al.: Soundness of Workflow Nets with Reset Arcs is
Undecidable! In J. Kleijn and M. Koutny, editors, Proceedings of the
International Workshop on Concurrency Methods Issues and Applications
(CHINA'08), pages 57-72 (2008)
• Trcka, N., van der Aalst, W.M.P., Sidorova, N.: Data-Flow Anti-Patterns:
Discovering Data-Flow Errors in Workflows, CAiSE 2009, LNCS, 2009.
• Rozinat, A., van der Aalst, W.M.P.: Conformance Checking of Processes
Based on Monitoring Real Behavior. Information Systems, 33(1):64-95, (2008)
• van der Aalst, W.M.P., Dumas, M., Ouyang, C., Rozinat, A., Verbeek, H.M.W.:
Conformance Checking of Service Behavior. ACM Transactions on Internet
Technology, 8(3):29-59 (2008)
PAGE 48

50. Recommended Reading (3/3)
• Ouyang, C., van der Aalst, W.M.P., Breutel, S., Dumas, M., ter Hofstede, A.H.M.,
Verbeek, H.M.W.: Formal Semantics and Analysis of Control Flow in WS-BPEL.
Science of Computer Programming, 67(2-3):162-198, 2007.
• C. Ouyang, E. Verbeek, W.M.P. van der Aalst, S. Breutel, M. Dumas, and A.H.M. ter
Hofstede. WofBPEL: A Tool for Automated Analysis of BPEL Processes. In
B. Benatallah, F. Casati, and P. Traverso, editors, Proceedings of Service-Oriented
Computing (ICSOC 2005), volume 3826 of Lecture Notes in Computer Science,
pages 484-489. Springer-Verlag, Berlin, 2005.
• H.M.W. Verbeek and W.M.P. van der Aalst. Analyzing BPEL Processes using Petri
Nets. In D. Marinescu, editor, Proceedings of the Second International Workshop on
Applications of Petri Nets to Coordination, Workflow and Business Process
Management, pages 59-78. Florida International University, Miami, Florida, USA,
2005.
• Lohmann, N., Massuthe, P., Stahl, C., Weinberg, D.: Analyzing interacting WSBPEL
processes using flexible model generation. Data & Knowledge Engineering, 64(1),
38–54 (2008)
• van der Aalst, W.M.P., Lassen, K.B.: Translating Unstructured Workflow Processes to
Readable BPEL: Theory and Implementation. Information and Software Technology,
50(3):131-159 (2008)
• C. Ouyang, M. Dumas, A.H.M. ter Hofstede, and W.M.P. van der Aalst. Pattern-
Based Translation of BPMN Process Models to BPEL Web Services. International
Journal of Web Services Research, 5(1):42-62 (2007)
PAGE 49

51. A "Crash Course" in
Petri Nets

52. Rules
free
wait enter before make_picture after leave gone
occupied
• Connections are directed.
• No connections between two places or two transitions.
• Places may hold zero or more tokens.
• First, we consider the case of at most one arc between two
nodes.
PAGE 51

53. Enabled
• A transition is enabled if each of its input places
contains at least one token.
free
wait enter before make_picture after leave gone
occupied
enabled Not Not
enabled enabled
PAGE 52

54. Firing
• An enabled transition can fire (i.e., it occurs).
• When it fires it consumes a token from each input
place and produces a token for each output place.
free
wait enter before make_picture after leave gone
fire
occupied
Etc.
PAGE 53

55. Example: Traffic Lights
rg1 rg2
g1 g2
r1 go1 x go2 r2
o1 o2
or1 or2
PAGE 54

56. Example: Producers and Consumers
start_production start_consumption
free producer wait consumer
product
end_production end_consumption
PAGE 55

57. Example: Four Philosophers
st1
e1 t1
se1
c4 c1
t4 e2
st4 se4 se2 st2
e4 t2
c3 c2
se3
t3 e3
st3
PAGE 56

58. Definition: Petri Net
start_production start_consumption
free producer wait consumer
product
end_production end_consumption
PAGE 57

59. Pre- and Post-Set
start_production start_consumption
free producer wait consumer
product
end_production end_consumption
PAGE 58

60. Firing Rule
start_production start_consumption start_production start_consumption
free producer wait consumer free producer wait consumer
product product
end_production
end_production end_consumption end_production end_consumption
PAGE 59

61. Open Nets
p5
p1
accept
place
order
p6
p2
eat cook
food
p3 p7
pay collect
money
p4 p8
PAGE 60

62. Example
p1
place
p2
order
O
I
eat
food
leave p3
pay song
money
p4
Ω={[p4]} PAGE 61

63. Some More Definitions
start_production start_consumption
free
free producer wait consumer
product
end_production end_consumption
PAGE 62

64. Interface Compatible
p1 p5 p1 p5
place accept place accept
order order order
p2 p6 p2 p6
eat cook eat cook
food food food food
leave p3 p7 get drunk leave p3 p7 get drunk
pay song song collect pay song song collect
money money money
p4 p8 p4 p8
PAGE 63

65. Composition
PAGE 64

66. Compose
p1 p5
place accept
order
p2 p6
eat cook
food food
leave p3 p7 get drunk
pay song song collect
money
p4 p8
Ω={[p4]} Ω={[p8]} PAGE 65

67. Composed Net
p1 order p5
place accept
p2 p6
eat cook
food
leave p3 p7 get drunk
pay song collect
p4 money p8
Ω={[p4,p8]}
PAGE 66

68. Deadlock Free
p1 p5
place accept
order
p2 p6
eat cook
food
leave p3 p7 get drunk
pay song collect
money
Ω={[p4,p8]} p4 p8
PAGE 67

69. Deadlock Free ?
p1 p5
place accept
order
p2 p6
eat cook
food
p3 p7 get drunk
pay song collect
money
Ω={[p4,p8]} p4 p8
PAGE 68

70. Strategy & Controllability
p1 p5
M p1 p5
N place accept
place accept order
p2 p6
N in Strat(M) order order
p2 p6 M in Strat(N)
eat cook
food
leave p3 p7 get drunk
eat cook
pay song collect
food food
leave p3 p7 get drunk money
song song p4 p8
pay collect
money money
p4 p8 M N
M is controllable N is controllable PAGE 69

71. Controllable ?
N c1
Ω={[c4]}
Strat(N) = ø
internal1 internal2
c2 c3
receive1 receive2 p1
c4 p2
AP-1: Internal Choice Receiving Follow-Up Anti-Pattern
PAGE 70

72. Controllable?
p1 p1 p1
place place place
order order order
p2 p2 p2
eat eat eat
food food food
p3 leave p3 leave p3
pay pay song
pay
money money money
p4 p4 p4
PAGE 71

73. Controllable?
p5 p5 p5
accept accept accept
order order order
p6 p6 p6
cook collect cook
food food food
p7 p7 p7 get drunk
song collect
collect cook
money money money
p8 p8 p8
PAGE 72

74. Controllable?
p1 p5
place accept
order order
p2 p6
eat cook
food food
p3 p7 get drunk
pay collect
Ω={[p2,p4]} money money
p4 p8
PAGE 73

75. Possible Additional Requirements to
Rule Out Undesirable Strategies
p1 p5
place accept
order order
p6
p2
eat cook
food food
leave p7 get drunk
p3
pay collect
money money
p4 p8
No dead transitions / Ω states need to be dead
interface places
PAGE 74

76. Recommended Reading
• van der Aalst, W.: The Application of Petri Nets to Workflow Management.
The Journal of Circuits, Systems and Computers 8(1), 21–66 (1998)
• van der Aalst, W.M.P.: Business Process Management Demystified: A
Tutorial on Models, Systems and Standards for Workflow Management. In
J. Desel, W. Reisig, and G. Rozenberg, editors, Lectures on Concurrency
and Petri Nets, volume 3098 of Lecture Notes in Computer Science, pages
1-65. Springer-Verlag, Berlin, 2004.
• Desel, J., Esparza, J.: Free Choice Petri Nets. Cambridge Tracts in
Theoretical Computer Science, vol. 40. Cambridge University Press,
Cambridge (1995)
• Murata, T.: Petri Nets: Properties, Analysis and Applications. Proceedings of
the IEEE 77(4), 541–580 (1989)
• Reisig, W.: Petri Nets: An Introduction. EATCS Monographs in Theoretical
Computer Science, vol. 4. Springer, Berlin (1985)
PAGE 75

77. Exposing Services

78. Exposing Services
Service Broker
repository
find publish
exposed
bind
Service Requester Service Provider
Services also need to be exposed in the bilateral case! PAGE 77

79. Two main approaches
• Selecting a service means to find for a given service R (whose
behavior is given) a compatible service S in the repository.
• One approach is to expose the behavior of S (this needs to be
done for all services in the repository).
• Well-behavior of the composition of R and S can be verified using
standard state space verification techniques.
• However, organizations usually want to hide the trade secrets of
their services and thus need to find a proper abstraction of S which
is published.
• Another approach is to not expose the behavior of S, but a class of
services R that is compatible with S, e.g., the set Strat(S).
• Then the composition of R and S is compatible if Strat(S) contains
R. From the set of strategies it is in general not possible to derive
the original service.
PAGE 78

80. First Approach
p5
p1
accept
p5
repository
place ? p6
accept
cook
order
p6
p2 p7
p5
collect
collect
accept
eat p8 p7 order
p6
food cook
? S cook
p3 p8
food
get drunk
p7
song collect
S
pay
? money
p8
money
p4 S
R PAGE 79

81. Second Approach
p1
repository
place ? Strat(S)
order
p2
eat
food Strat(S)
p3
?
pay
? Strat(S)
money
p4
R PAGE 80

82. Operating Guidelines
• We advocate the second approach for reasons of
efficiency and hiding trade secrets.
• Problem: Strat(S) is typically infinite!
• Operating guidelines provide a finite representation
of a possibly infinite set of compatible services.
• Here we do not explain how the operating guideline is
computed (see recommended reading) and focus on
its application.
PAGE 81

83. Basic Idea
p1 ? p5
accept
place
order
order
p6
p2 !order
r2
?food cook
eat
r3 food
food
!money p7
p3
r4
collect
pay
TS(GS1) OG(RS1) money
money
p8
p4 RS1
PAGE 82
GS1

84. (2) constraints of
Matching corresponding states are
satisfied
(1) simulation relation
(weak simulation)
!order
r2
?food
r3
!money
r4
TS(GS1) OG(RS1)
PAGE 83

85. Weak simulation
• R weakly simulates P iff R can mimic any
behavior of P.
• Formally, there exists a weak simulation relation
such that:
p r p r
τ τ
∗
a τ ∗
p’ r’ p’ r’
a
r’ PAGE 84

86. R does not weakly simulate P
P R
1 1
ask ask
ask
question question
question
2 2a 2b
p r
yes no yes no
3 4 3 4
p'
PAGE 85

87. R weakly simulates P, but ...
P does not weakly simulate R
P R
1 1
smoke smoke
2 smoke 2
smoke die die
smoke live rip rip
die
PAGE 86

88. Evaluating Expressions
expr1 = a! or b? or c! or d? or f?
expr1 = (a! or b? or c!) and d?
expr1 = (a! and final) or d!
s1: expr1
a! e?
a! c! b? d?
b?
s2: expr2 s6: expr6
c!
s3: expr3 s5: expr5
s4: expr4
PAGE 87

89. GS1 is a Strategy for RS1
p1 ? p5
accept
place
order
order
p6
p2 !order
r2
?food cook
eat
r3 food
food
!money p7
p3
r4
collect
pay
TS(GS1) OG(RS1) money
money
p8
p4 RS1
PAGE 88
GS1

90. Operating Guideline
• N is an open net
• BΦ is a Boolean Annotated Service Automaton
(BSA), i.e., an automaton with annotated states that
aims to describe (possible infinite) sets of open nets
• Match(BΦ) is the set of all open nets that match with
BΦ (all nets that are weakly simulated by BΦ such that
constraints of corresponding states are satisfied)
• OG(N) is the operating guideline for N, i.e., a BSA BΦ
such that Match(BΦ) = Strat(N)
PAGE 89

91. Another Example
?
order order
r5
!order
food r6 food
?food ?
τ r7
!money money
money
r8
PAGE 90

92. Not Matching
r5
!order
r6
?food
τ r7
!money
r8
PAGE 91

93. Repaired Service Behavior
r5
!order
r6
?food
r7
!money
r8
PAGE 92

94. Most Permissive Strategy
PAGE 93

95. Recommended Reading
• van der Aalst, W., Mooij, A.J., Stahl C., Wolf, K.. Service Interaction:
Patterns, Formalization, and Analysis. In SFM 2009, volume 5569 of Lecture
Notes in Computer Science, pages 42-88. Springer-Verlag, Berlin (2009)
• van der Aalst, W., Lohmann, N., Massuthe, P., Stahl, C., Wolf, K.: From
Public Views to Private Views: Correctness-by-Design for Services. In:
Dumas, M., Heckel, H. (eds.) WS-FM 2007. LNCS, vol. 4937, pp. 139–153.
Springer, Heidelberg (2008)
• Massuthe, P., Reisig, W., Schmidt, K.: An Operating Guideline Approach to
the SOA. Annals of Mathematics, Computing & Teleinformatics 1(3), 35–43
(2005)
• Wolf, K.: Does my service have partners? In: ToPNoC II 2008. LNCS, vol.
5460, pp. 152–171. Springer, Heidelberg (2008)
• Massuthe, P., Reisig, W., Schmidt, K.: An Operating Guideline Approach to
the SOA. In: Proceedings of the 2nd South-East European Workshop on
Formal Methods 2005 (SEEFM 2005), Ohrid, Republic of Macedonia (2005)
PAGE 94

96. Replacing and
Refining Services

97. Replacing or Refining Services
service
replace service
or A
refine D
service service
B C
PAGE 96

98. Accordance
service
service service
A’
A D
Strat(A) subset
of Strat(A') Strat(C) subset
service service
service of Strat(C')
B C’
C
PAGE 97

99. Projection Inheritance is Too Strict
p5 p5
accords with
accept accept
order order
p6
(while there is p6
no inheritance
cook relation) cook
food food
p7 p7
collect
collect
money money
p8 p8
PAGE 98

100. Refinement
Accordance can be checked using
operating guidelines!
Details not important at this stage.
PAGE 99

101. Transformation Rules
P P
A B
X Y
Strat(X) = Strat(Y)
PAGE 100

102. Inheritance Preserving Transformation
Rules (1/2)
R R R
Ai Ai Ai
a a a
Ao Ao Ao
d p1
p1 p3 p1
Bi Bi Bi
b b d b
Bo Bo Bo
p2 p2 p4 p2
Ci Ci Ci
c c c
Co Co Co
S S S
PAGE 101

103. Inheritance Preserving Transformation
Rules (2/2)
R R
Inheritance
Ai Ai preserving
a a
Ao Ao transformation
rules also
p1 p3 p1
preserve
Bi Bi accordance!
b d b
Bo Bo
p2 p2
Ci Ci
c c But are too
Co Co
strong ...
S S
PAGE 102

104. Accordance Preserving Transformation
Rule 1
R R
t1 a a
p
= t12
t2 b b
S S
PAGE 103

105. Accordance Preserving Transformation
Rule 2
R R
t1 a a
p
= t12
t2 b b
S S
PAGE 104

106. Accordance Preserving Transformation
Rule 3
R R
t1 a a
p
= t12
t2 b b
S S
PAGE 105

107. Accordance Preserving Transformation
Rule 4
R R
t1 t1
a p1 p2 a
p
= t2 t3
b p3 p4 b
t2 t4
S S PAGE 106

108. Another Type of Anti Pattern
R R
t1 a t1 a
p p
t2 b t2 b
S S
PAGE 107

109. Strategy for one net and not the other
p1 p1
R t3 R t3
R R
p2 p2
t1 a a t4 t1 a a t4
p p3 p p3
t2 b b t5 t2 b b t5
p4 p4
S S
S t6 S t6PAGE 108

110. Strategy for one net and not the other
p1 p1
R t3 R t3
R R
p2 p2
t1 a t1 a a t4 t7
a t4 t7
p p3 p5 p p3 p5
b t5 b t5
t2 b t2 b
p4 p4
S S
S t6 S t6
PAGE 109

111. Accordance Preserving Transformation
Rule 5
R R
t1 a t6 t1 a
p1 f p4 p1 f
⊆
t2 t3 t7 t2 t3
b b
c c
p2 p3 p2 p3
t4 t5 t4 t5
d d
e e
S S
PAGE 110

112. Recommended Reading
• van der Aalst, W., Mooij, A.J., Stahl C., Wolf, K.. Service Interaction:
Patterns, Formalization, and Analysis. In SFM 2009, volume 5569 of Lecture
Notes in Computer Science, pages 42-88. Springer-Verlag, Berlin, (2009)
• van der Aalst, W., Lohmann, N., Massuthe, P., Stahl, C., Wolf, K.: From
Public Views to Private Views: Correctness-by-Design for Services. In:
Dumas, M., Heckel, H. (eds.) WS-FM 2007. LNCS, vol. 4937, pp. 139–153.
Springer, Heidelberg (2008)
• Basten, T., Aalst, W.: Inheritance of Behavior. Journal of Logic and
Algebraic Programming 47(2), 47–145 (2001)
• van der Aalst, W.M.P., Basten, T.: Inheritance of Workflows: An Approach to
Tackling Problems Related to Change. Theoretical Computer Science,
270(1-2):125-203 (2002)
PAGE 111

113. Integrating Services
Using Adapters

114. The Need For Adapters
?
service service
A B
service service
adapter
A B
PAGE 113

115. Example
tourist cook
cOrder
tFood
? cFood
tMoney cMoney
PAGE 114

116. Adapter
tourist cook
cOrder cOrder
tFood tFood cFood cFood
tMoney tMoney cMoney cMoney
adapter PAGE 115

117. Adapter ?????
tourist cook
cOrder cOrder
tFood tFood cFood cFood
tMoney tMoney cMoney cMoney
adapter PAGE 116

118. Specification of Elementary Activities (SEA)
• To avoid creating money, deleting evidence,
confusing meters with liters, etc.
PAGE 117

119. SEA Example
tourist cook
cOrder
tFood cFood
cOrder
tFood cFood
tMoney cMoney
tMoney cMoney
PAGE 118

120. Overall Idea
Controller
cOrder
tFood cFood
SEA-
Based
Engine
tMoney cMoney
PAGE 119

121. SEA-Based Engine n = notify
e = enable
(tFood,e) (tMoney,n) (food,e) (food,n) (order,e) (order,n) (money,e) (money,n) (cFood,n) (cOrder,e) (cMoney,e)
(order,c) (cOrder,c) (cOrder,s) cOrder
(tFood,s) (tFood,c) (food,c) (cFood,c) (cFood,r)
tFood cFood
(tMoney,r) (tMoney,c) (money,c) (cMoney,c) (cMoney,s)
tMoney cMoney
s=send n = notify
r=receive e = enable
c=actual transformation
PAGE 120

122. Business As Usual ...
• Selecting a controller is like selecting a strategy.
• One approach is to construct "the" most permissive one
Controller
(tFood,e) (tMoney,n) (food,e) (food,n) (order,e) (order,n) (money,e) (money,n) (cFood,n) (cOrder,e) (cMoney,e)
(order,c) (cOrder,c) (cOrder,s) cOrder cOrder
tFood tFood (tFood,s) (tFood,c) (food,c) (cFood,c) (cFood,r)
cFood cFood
tMoney (tMoney,r) (tMoney,c) (money,c) (cMoney,c) (cMoney,s)
tMoney cMoney cMoney
PAGE 121

123. Recommended Reading
• van der Aalst, W., Mooij, A.J., Stahl C., Wolf, K.. Service Interaction:
Patterns, Formalization, and Analysis. In SFM 2009, volume 5569 of Lecture
Notes in Computer Science, pages 42-88. Springer-Verlag, Berlin, 2009.
• Gierds, C., Mooij, A., Wolf, K.: Specifying and generating behavioral service
adapters based on transformation rules. Preprints CS-02-08, Institut fur
Informatik, Universität Rostock (2008)
• Mooij, A., Voorhoeve, M.: Proof techniques for adapter generation. In: Proc.
WSFM (2008)
PAGE 122

124. Service Mining

125. Correctness at "model-time" is irrelevant!
PAGE 124

126. PAGE 125

127. PAGE 126

128. Process Mining
• Process discovery: "What is
really happening?"
• Conformance checking: "Do
we do what was agreed
upon?"
• Performance analysis:
"Where are the bottlenecks?"
• Process prediction: "Will this
case be late?"
• Process improvement: "How
to redesign this process?"
• Etc.
PAGE 127

129. • Process discovery: "What is the real curriculum?"
• Conformance checking: "Do students meet the prerequisites?"
• Performance analysis: "Where are the bottlenecks?"
• Process prediction: "Will a student complete his studies (in time)?"
• Process improvement: "How to redesign the curriculum?"
PAGE 128

130. Screenshot of ProM 5.0
PAGE 129

131. Example Setting for Service Mining
BPEL choreography
PAGE 130

132. PAGE 131

133. Recommended Reading
• van der Aalst, W.M.P., Dumas, M., Ouyang, C., Rozinat, A., Verbeek,
H.M.W.: Conformance Checking of Service Behavior. ACM Transactions on
Internet Technology, 8(3):29-59, 2008.
• Rozinat, A., van der Aalst, W.M.P.: Conformance Checking of Processes
Based on Monitoring Real Behavior. Information Systems, 33(1):64-95,
2008.
• van der Aalst, W.M.P., Reijers, H.A., Weijters, A.J.M.M., van Dongen, B.F.,
Alves de Medeiros, A.K., Song, M., Verbeek, H.M.W.: Business Process
Mining: An Industrial Application. Information Systems, 32(5):713-732, 2007.
• www.processmining.org
• Process Mining: Discovery, Conformance and Enhancement of Business
Processes by W.M.P. van der Aalst, Springer Verlag, 2011 (ISBN 978-3-
642-19344-6). http://www.processmining.org/book/
PAGE 132

134. Conclusion

135. Service Interaction Demystified
service service
A D
service service
• Patterns and B C
Anti-Patterns
• Formalization
• Analysis
PAGE 134

136. Questions Addressed
1. Exposing Services
 How to inform others about me such that cooperation
is possible?
 Two approaches: (a) expose own behavior and (b)
provide operating guideline.
2. Replacing and Refining Services
 How to replace or refine a service without introducing
problems?
 Inheritance, accordance, transformation rules, etc.
3. Integrating Services Using Adapters
 How to resolve behavioral incompatibilities?
 Adapter generation.
4. Service Mining
 How to analyze the run-time behavior?
PAGE 135

137. Relevant WWW sites
• http://www2.informatik.hu-berlin.de/top/best/
• http://www.service-technology.org
• http://www.workflowpatterns.com
• http://www.processmining.org
• http://promimport.sourceforge.net
• http://prom.sourceforge.net
• http://www.workflowcourse.com
• http://www.vdaalst.com
PAGE 136