Workshop presentation given by Niels Lohmann on August 16, 2007 in Eindhoven, The Netherlands at the Berlin-Eindhoven Service Technology Colloquium 2007 (B.E.S.T. 2007).

1. Diagnosis of Open Workflow Nets
B.E.S.T Meeting
August 16, 2007
Niels Lohmann
www.informatik.hu-berlin.de/~nlohmann

2. Controllability
Diagnosis of Open Workflow Nets
! Definition: existence of a partner s.t. composition is
weakly terminating
! Can be constructively decided using the algorithm
implemented in the tool Fiona
! Today: acyclic nets
2

3. Interaction Graph
Diagnosis of Open Workflow Nets
p1
x a
p2 p3
b y
p4
3

4. Interaction Graph transient
state
Diagnosis of Open Workflow Nets
[p1] (TR)
p1
x a
p2 p3
b y
p4
3

5. Interaction Graph transient external
state deadlock
Diagnosis of Open Workflow Nets
[p1] (TR)
[p3, a] (eDL)
p1
x a
p2 p3
b y
p4
3

6. Interaction Graph transient external
state deadlock
Diagnosis of Open Workflow Nets
[p1] (TR)
[p3, a] (eDL)
p1 ?a
x a
p2 p3
b y
p4
3

7. Interaction Graph transient external
state deadlock
Diagnosis of Open Workflow Nets
[p1] (TR)
[p3, a] (eDL)
p1 ?a
[p3] (eDL)
x a
p2 p3
b y
p4
3

8. Interaction Graph transient external
state deadlock
Diagnosis of Open Workflow Nets
[p1] (TR)
[p3, a] (eDL)
p1 ?a
[p3] (eDL)
x a
!y
p2 p3
[p3, y] (TR)
[p4] (FS)
b y
final
p4 state
3

9. Interaction Graph transient external
state deadlock
Diagnosis of Open Workflow Nets
[p1] (TR)
[p3, a] (eDL)
p1 !x ?a
[p1, x] (TR) [p3] (eDL)
x a [p2] (TR)
[p4, b] (eDL)
[p3, a, x] (eDL)
!y
p2 p3
[p3, y] (TR)
[p4] (FS)
b y
final
p4 state
3

10. Interaction Graph transient external
state deadlock
Diagnosis of Open Workflow Nets
[p1] (TR)
[p3, a] (eDL)
p1 !x ?a
[p1, x] (TR) [p3] (eDL)
x a [p2] (TR)
[p4, b] (eDL)
[p3, a, x] (eDL)
!y
p2 p3
?a [p3, y] (TR)
[p4] (FS)
b y [p3, x] (eDL)
final
p4 state
3

11. Interaction Graph transient external
state deadlock
Diagnosis of Open Workflow Nets
[p1] (TR)
[p3, a] (eDL)
p1 !x ?a
[p1, x] (TR) [p3] (eDL)
x a [p2] (TR)
[p4, b] (eDL)
[p3, a, x] (eDL)
!y
p2 p3
?a [p3, y] (TR)
[p4] (FS)
b y [p3, x] (eDL)
!y final
p4 state
[p3, x, y] (TR)
[p4, x] (iDL)
internal
deadlock
3

12. Interaction Graph (cont.)
Diagnosis of Open Workflow Nets
blue rooted subgraph:
net is controllable!
p1
x a
p2 p3
b y
p4
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13. Interaction Graph (cont.)
Diagnosis of Open Workflow Nets
p1
x a a x
p2 p3
b y y b
p4
4

14. Uncontrollable Nets
Diagnosis of Open Workflow Nets
p1 p1
x a
p2 p3 p2 p3
x y b
p4 p4
Guess the net’s decision! Net can deadlock in [p3].
“non-local choice”
5

15. Interaction Graphs
Diagnosis of Open Workflow Nets
em?
p robl
th e
h at is
W
6

16. Diagnosis of Open Workflow Nets
7
More Colors = Better

17. Diagnosis of Open Workflow Nets
7
More Colors = Better

18. More Colors = Better
Diagnosis of Open Workflow Nets
blue node:
AF final state
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19. More Colors = Better
Diagnosis of Open Workflow Nets
blue node: red node:
AF final state AF deadlock
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20. More Colors = Better
Diagnosis of Open Workflow Nets
yellow node:
be careful!
blue node: red node:
AF final state AF deadlock
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21. More Colors = Better green node: nothing
bad happened (yet)
Diagnosis of Open Workflow Nets
yellow node:
be careful!
blue node: red node:
AF final state AF deadlock
7

22. More Colors = Better green node: nothing
bad happened (yet)
Diagnosis of Open Workflow Nets
yellow node:
be careful!
blue node: red node:
AF final state AF deadlock
7

23. More Colors = Better green node: nothing
bad happened (yet)
Diagnosis of Open Workflow Nets
yellow node:
be careful!
trace to problem
states
blue node: red node:
AF final state AF deadlock
7

24. Goals of my Thesis
Diagnosis of Open Workflow Nets
1. Diagnosis: Why is a net uncontrollable?
“non-local choice between [p2,p3] and [p1,p4]”
8

25. Goals of my Thesis
Diagnosis of Open Workflow Nets
1. Diagnosis: Why is a net uncontrollable?
“non-local choice between [p2,p3] and [p1,p4]”
2. Error location: Where is the problem?
“un-communicated decision between t1 and t2”
8

26. Goals of my Thesis
Diagnosis of Open Workflow Nets
1. Diagnosis: Why is a net uncontrollable?
“non-local choice between [p2,p3] and [p1,p4]”
2. Error location: Where is the problem?
“un-communicated decision between t1 and t2”
3. Correction: What to change?
“t1 must send a message”
8

27. Goals of my Thesis
Diagnosis of Open Workflow Nets
1. Diagnosis: Why is a net uncontrollable?
“non-local choice between [p2,p3] and [p1,p4]”
2. Error location: Where is the problem?
“un-communicated decision between t1 and t2”
3. Correction: What to change?
“t1 must send a message”
4. Optimization: Can it be done with less messages?
“message x sent by t3 is not necessary”
8

28. Goals of my Thesis (cont.)
Diagnosis of Open Workflow Nets
Variations of the diagnosis setting:
! Structure:
! Cyclic nets:
new problems: livelocks, unbounded channels
! Composition of several nets:
new question: responsibility for deadlocks
! Property:
! Distributed controllability:
stronger criterion
! Controllability under constraints:
di!erent/fewer final states
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29. Questions?
Diagnosis of Open Workflow Nets
DIAGNOSIS
OF
OPEN
WORKFLOW
NETS
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