Niels Lohmannwww.informatik.hu-berlin.de/~nlohmann

Diagnosis of Open Workflow NetsDiagnosis of Open Workflow Nets

B.E.S.T MeetingAugust 16, 2007

Diagnosis of O

pen Workflow

Nets

2

Controllability

! 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

Diagnosis of O

pen Workflow

Nets

3

Interaction Graph

x

b

a

y

p1

p3

p4

p2

Diagnosis of O

pen Workflow

Nets

3

Interaction Graph

x

b

a

y

p1

p3

p4

p2

[p1] (TR)

transientstate

Diagnosis of O

pen Workflow

Nets

3

Interaction Graph

x

b

a

y

p1

p3

p4

p2

[p1] (TR)[p3, a] (eDL)

externaldeadlock

transientstate

Diagnosis of O

pen Workflow

Nets

3

Interaction Graph

x

b

a

y

p1

p3

p4

p2

[p1] (TR)[p3, a] (eDL)

?a

externaldeadlock

transientstate

Diagnosis of O

pen Workflow

Nets

3

Interaction Graph

x

b

a

y

p1

p3

p4

p2

[p1] (TR)[p3, a] (eDL)

[p3] (eDL)

?a

externaldeadlock

transientstate

Diagnosis of O

pen Workflow

Nets

3

Interaction Graph

x

b

a

y

p1

p3

p4

p2

[p1] (TR)[p3, a] (eDL)

[p3] (eDL)

[p3, y] (TR)[p4] (FS)

?a

!y

externaldeadlock

transientstate

finalstate

Diagnosis of O

pen Workflow

Nets

3

Interaction Graph

x

b

a

y

p1

p3

p4

p2

[p1] (TR)[p3, a] (eDL)

[p1, x] (TR)

[p3, a, x] (eDL)

[p2] (TR)[p4, b] (eDL)

[p3] (eDL)

[p3, y] (TR)[p4] (FS)

!x ?a

!y

externaldeadlock

transientstate

finalstate

Diagnosis of O

pen Workflow

Nets

3

Interaction Graph

x

b

a

y

p1

p3

p4

p2

[p1] (TR)[p3, a] (eDL)

[p1, x] (TR)

[p3, a, x] (eDL)

[p2] (TR)[p4, b] (eDL)

[p3] (eDL)

[p3, y] (TR)[p4] (FS)

[p3, x] (eDL)

!x

?a

?a

!y

externaldeadlock

transientstate

finalstate

Diagnosis of O

pen Workflow

Nets

3

Interaction Graph

x

b

a

y

p1

p3

p4

p2

[p1] (TR)[p3, a] (eDL)

[p1, x] (TR)

[p3, a, x] (eDL)

[p2] (TR)[p4, b] (eDL)

[p3] (eDL)

[p3, y] (TR)[p4] (FS)

[p3, x] (eDL)

[p3, x, y] (TR)[p4, x] (iDL)

!x

?a

!y

?a

!y

externaldeadlock

transientstate

finalstate

internaldeadlock

Diagnosis of O

pen Workflow

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Interaction Graph (cont.)

x

b

a

y

p1

p3

p4

p2

blue rooted subgraph:net is controllable!

Diagnosis of O

pen Workflow

Nets

4

Interaction Graph (cont.)

x

b

a

y

p1

p3

p4

p2

a

y

x

b

Diagnosis of O

pen Workflow

Nets

5

Uncontrollable Nets

x y

p1

p3

p4

p2

x

b

a

p1

p3

p4

p2

Guess the net’s decision!“non-local choice”

Net can deadlock in [p3].

Diagnosis of O

pen Workflow

Nets

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Interaction Graphs

What is the problem?

Diagnosis of O

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More Colors = Better

Diagnosis of O

pen Workflow

Nets

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More Colors = Better

Diagnosis of O

pen Workflow

Nets

7

More Colors = Better

blue node:AF final state

Diagnosis of O

pen Workflow

Nets

7

More Colors = Better

blue node:AF final state

red node:AF deadlock

Diagnosis of O

pen Workflow

Nets

7

More Colors = Better

blue node:AF final state

red node:AF deadlock

yellow node:be careful!

Diagnosis of O

pen Workflow

Nets

7

More Colors = Better

blue node:AF final state

red node:AF deadlock

yellow node:be careful!

green node: nothingbad happened (yet)

Diagnosis of O

pen Workflow

Nets

7

More Colors = Better

blue node:AF final state

red node:AF deadlock

yellow node:be careful!

green node: nothingbad happened (yet)

Diagnosis of O

pen Workflow

Nets

7

More Colors = Better

blue node:AF final state

red node:AF deadlock

yellow node:be careful!

green node: nothingbad happened (yet)

trace to problem states

Diagnosis of O

pen Workflow

Nets

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Goals of my Thesis

1. Diagnosis: Why is a net uncontrollable?“non-local choice between [p2,p3] and [p1,p4]”

Diagnosis of O

pen Workflow

Nets

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Goals of my Thesis

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”

Diagnosis of O

pen Workflow

Nets

8

Goals of my Thesis

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”

Diagnosis of O

pen Workflow

Nets

8

Goals of my Thesis

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”

Diagnosis of O

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Goals of my Thesis (cont.)

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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Questions?

DIAGNOSISOF

OPENWORKFLOW

NETS