wendy: a tool to synthesize partners for services

Wendy:a tool to synthesize partners for services

Niels Lohmann and Daniela Weinberg

Wendy: a tool to synthesize partners for services24.06.10 2

Correctness of services

• correctness notions like soundness only applicable to internal behavior

• need to consider communication via interface

• service is correct iff there exists a partner service such that composition is compatible

• compatible = deadlock/livelock free

• aka “controllability”

service

interface

partnerservice

interface


Controllability

• synthesized partner can be usedin many scenarios– documentation– communication proxy– choreography completion– service validation– adapter generation– process configuration– runtime migration– …

• Wendy automatically synthesizes such partners!

service

interface

partnerservice

interface


Formal model

• open net = Petri net+ interface+ final markings

• asynchronous + synchronous communication

• final markings modeldesired end states

offer

reject

accept

invoice

p1

p2

p3 p4

p5


Formal model

• composition = place fusion / transition fusion

offer

reject

accept

invoice

p1

p2

p3 p4

p5

offer

reject

accept

invoice

q1

q2

q3 q4

q5


Formal model

• compatibility = deadlock/livelock freedom + k-bounded interface

p1

p2

p3 p4

p5

q1

q2

q3 q4

q5

offer

reject

accept

invoice


Wendy

Wendyservice(open net)

LoLA-like formatPNML dialect

partner(automaton)

LoLA-like format

Petrify/Genetpartner(open net)


Basic algorithm

1. overapproximation:– serve the interface (send,

receive, synchronize)– observe net’s behavior

2. removal of bad nodes:– remove nodes with deadlocks– remove nodes with unreachable

final marking– remove nodes with message

bound violations

offer

reject

accept

invoice

p1

p2

p3 p4

p5


Basic algorithm

offer

reject

accept

invoice

p1

p2

p3 p4

p5

[p1]

[p2][p3, reject][p1, reject][p4, accept]

[p4]

[p4, invoice][p5]

[p1, invoice]

[p2, invoice][p3, reject, invoice]

[p1, invoice][p4, accept, invoice]

!invoice

#offer #offer

!invoice

?accept?accept

• observation: we store many small state spaces

?reject?reject

!inv.


Experimental results

1

10

100

1000

10000

100000

1000000

10000000

1 10 100 1000 10000 100000 1000000 10000000

node

s of s

ynthe

sized

partn

er

reachable markings of analyzed open net

Asynchronous Sequence(academic)

Choreographies(academic)

Philosophers(academic)

BPEL Processes (industrial)


Improvements

• observation: we generate markings of the net again and again• idea: generate complete state space of net once and for all• advantage: compact storage + early detection of “bad” situations• “powered by LoLA”

• furthermore– exploiting regularities– more compact data structures– reimplementing “standard data types”

• compared to earlier implementation Fiona:– 5 to 70 times faster*– 2 to 50 times less memory consumption*


Reduction Rules

• most-permissiveness is not always desired/necessary• reduction rules create smaller partners– no “sending in advance”– receive messages in single order– send whenever possible– only send if required (prefer receiving)

?x

?y #z

!b

!c!d

?x!d!c?x

!c!d

?x!c

?x !d

?y ?x #z

?x

?y

!b

?x

?x

?y

!b !c!d

?x !c !d

?y ?x #z

?x

?y

!b

?x

?y ?x


Operating guidelines

• finite characterization of all partners

• most-permissive partner+ Boolean formula

• more applications:– test case generation– choreography correction– service substitutability– public view generation– service brokerage (SOA)– …

?x

?y !?z

!b

!c!d

?x!d

!c?x!c!d

?x !c ?x !d

?y ?x !?z

c ∨ d ∨ x

b ∨ c ∨ d c ∨ x d ∨ x

x ∨ y c x ∨ z d

xy z

final


Integration

• ProM 6• YAWL Editor• Oryx• service-technology.org/live• your tool!


Try Wendy!

• Download: http://service-‐technology.org/wendy

• Online version: http://service-‐technology.org/live/wendy• Questions: wendy@service-‐technology.org


Take home points

Wendy…• synthesizes partners for services• can be used in many scenarios• performs well on (our) case studies

Next…• extend correctness criteria• elaborate stubborn set reduction for state space

(symbolic techniques?)• improve reduction rules

Niels LohmannUniversität [email protected]

wendy: a tool to synthesize partners for services

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