Efficient Controllability Analysis of Open Nets Workshop on Web Services and Formal Methods 2008 Daniela Weinberg

2 Efficient Controllability Analysis of Open Nets Setting  Service  self-contained software unit  encapsulated functionality with interface  designed to interact with other services service S S interacting with another service service modeling

3 Efficient Controllability Analysis of Open Nets  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

4 Efficient Controllability Analysis of Open Nets 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]}

5 Efficient Controllability Analysis of Open Nets Using the Online Portal  user as an automaton  Interaction Graph ?terms ?note ?stats !review !login

6 Efficient Controllability Analysis of Open Nets Filling out the Bubbles  nodes: set of states  transient states, deadlocks [p1] [p4, terms] [p2, note] [p3, stats, note] ?terms

7 Efficient Controllability Analysis of Open Nets Filling out the Bubbles  nodes: set of states  transient states, deadlocks [p1] [p4, terms] [p2, note] [p3, stats, note] ?terms !login [p4]

8 Efficient Controllability Analysis of Open Nets 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]

9 Efficient Controllability Analysis of Open Nets 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

10 Efficient Controllability Analysis of Open Nets Interaction Graph of Online Portal

11 Efficient Controllability Analysis of Open Nets Interaction Graph of Online Portal  Is our service controllable?  Does the IG contain a controller?  Classification of the nodes necessary

12 Efficient Controllability Analysis of Open Nets 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

13 Efficient Controllability Analysis of Open Nets 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]...

14 Efficient Controllability Analysis of Open Nets 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...

15 Efficient Controllability Analysis of Open Nets Reduced Interaction Graph I

16 Efficient Controllability Analysis of Open Nets 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...

17 Efficient Controllability Analysis of Open Nets 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...

18 Efficient Controllability Analysis of Open Nets Reduced Interaction Graph II

19 Efficient Controllability Analysis of Open Nets All Reduction Rules combined  all reduction rules can be combined

20 Efficient Controllability Analysis of Open Nets Reduced Interaction Graph III  all reduction rules combined: 6 nodes, 5 edges  full IG: 30 nodes, 31 edges

21 Efficient Controllability Analysis of Open Nets 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 

22 Efficient Controllability Analysis of Open Nets 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

23 Efficient Controllability Analysis of Open Nets See more  Web   slides, paper, tools, examples,...

Thanks a lot!

25 Efficient Controllability Analysis of Open Nets Case Study  repository of scientific services, industrial services or services taken from the WS-BPEL specification  use tool BPEL2oWFN to translate a WS-BPEL service into an open net and Fiona to calculate IG complete IGreduced IGreduction [%] service name#N#ET [s]#N#ET[s]#N#E online shop order processing car breakdown deliver goods