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09-05-2008
Efficient Controllability Analysis of Open Nets
Workshop on Web Services and Formal Methods 2008
Daniela Weinbergweinberg@informatik.hu-berlin.de
http://www.service-technology.org/wsfm2008
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Setting
Service self-contained software unit encapsulated functionality with interface designed to interact with other services
service SS interacting withanother serviceservice modeling
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question, whether there exists another service C such that S and C can interact properly
does the composition of S and C reach a final state without deadlocking and no messages are left pending on the interface
interaction is done asynchronously
Controllability
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Model of a Service
a service is modeled as an open net
Petri net with • output (yellow) places,• input (orange) places,• special initial state and
set of final states• acyclic
Example: online portal initial state: [p1] set of final states: {[p5]}
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Using the Online Portal
user as an automaton Interaction Graph
?terms ?note
?stats
!review
!login!login
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Filling out the Bubbles
nodes: set of states transient states, deadlocks
[p1][p4, terms][p2, note]
[p3, stats, note]
?terms
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Filling out the Bubbles
nodes: set of states transient states, deadlocks
[p1][p4, terms][p2, note]
[p3, stats, note]
?terms
!login
[p4]
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Filling out the Bubbles
nodes: set of states transient states, deadlocks
[p1][p4, terms][p2, note]
[p3, stats, note]
?terms
!login
[p4, login][p5]
[p4]
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Filling out the Bubbles
nodes: set of states transient states, deadlocks
[p1][p4, terms][p2, note]
[p3, stats, note]
?terms
[p4, login][p5]
[p4]
!review
...!login
...
?note
...?stats
...
!review... ?terms
...
...
?note
...?stats
...
...
!login
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Interaction Graph of Online Portal
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Interaction Graph of Online Portal
Is our service controllable? Does the IG contain a controller?
Classification of the nodes necessary
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The complete Interaction Graph
for real life services IG grows huge in size industrial service (open net: #P = 116, #E = 156)
complete IG: #Nodes = 1584, #Edges = 7473, time = 302s
solution: define reduction rules! reduced IG: #Nodes = 31, #Edges = 41, time
= 1s
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Activation of Events
state s activates an event a:
state s is a deadlock sending or receiving a
leads from s to a new state [p1]
[p4, terms][p2, note]
[p3, stats, note]
?note
...?stats
!review
...!login
...?terms
!login
[p4]
...
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Receiving before Sending
Idea: do not send anything as long as you can receive something
one state activates a receiving and a sending event
consider the receiving event only
[p1][p4, terms][p2, note]
[p3, stats, note]
?terms
?note
...?stats
...
!review
...!login
...
...
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Reduced Interaction Graph I
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Combining Receiving Events
Idea: receive as much as possible at once
a state activates more than one receiving event
combine all receiving events of one state to one event
[p1][p4, terms][p2, note]
[p3, stats, note]
?terms
?note
...?stats
...
!review
...!login
...
...
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Combining Receiving Events
Idea: receive as much as possible at once
a state activates more than one receiving event
combine all receiving events of one state to one event
[p1][p4, terms][p2, note]
[p3, stats, note]
!review
...!login
...
?stats, ?note
...?terms
...
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Reduced Interaction Graph II
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All Reduction Rules combined
all reduction rules can be combined
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Reduced Interaction Graph III
all reduction rules combined: 6 nodes, 5 edges
full IG: 30 nodes, 31 edges
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Take Home Points
our case studies show reduced interaction graph is an efficient
technique to decide controllability for most services reduction by >90%
IG and all reduction rules are integrated into tool Fiona
http://www.service-technology.org/fiona
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Future Work
define more reduction rules• which events are activated• reduce number of states stored in nodes
adapt techniques to work with cyclic open nets as well
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See more
Web http://www.service-technology.org/wsfm2008 slides, paper, tools, examples, ...
09-05-2008
Thanks a lot!
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