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Parameterized Interface Automata

Learn about Interface Models, Automata, and the concept of Parameterized Interface Automata as introduced by Luca De Alfaro and Thomas A. Henzinger in 2001, emphasizing top-down design and compatibility checking for component-based systems.

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Parameterized Interface Automata

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  1. Parameterized Interface Automata Shahram Esmaeilsabzali January 31, 2005

  2. Outline • Interface Models • Interface Automata • Parameterized Interface Automata

  3. Interface Models • Introduced by Luca De Alfaro and Thomas A. Henzinger in 2001 • Interface models: • Specify how systems can be used instead of speciyifying what systems do • Rely on helpful environments (optimistic) • Support top-down design

  4. An Example Interface • How vs. What • Optimistic vs. Pessimistic

  5. Main Idea • Interface models are meant to be: • Concise • Intuitive for top-down design • Useful for checking compatibility of component-based systems

  6. Interface Models (More Formally) • Well-formedness Criteria: • Support composition and refinement • Support top-down design • (f || g) and f’refinesf, then (f’ ||g)refines(f || g)

  7. Refinement • Interface models rely on helpful Env • A more refined interface should have more relaxed assumptions about the Env: • Lessinput assumptions-> Refined Interface should accept Env Inputs • More output guarantees-> Env should be able to accept refined Interface outputs

  8. Example • Assume x,y be inputs and z the output of an interface

  9. Composition • Interface composition is a partial, commutative, associative, binary operation that combines the two interfaces’: • Behaviours of the two interfaces • Environmental assumptions of the two interfaces

  10. Top-down Design • Such Composition and Refinement relations imply top-down design Stronger Output Guarantee Weaker Input assumptions Refinement

  11. Top-Down Design: Compositional Refinement abstract Refined

  12. Outline • Interface Models • Interface Automata • Parameterized Interface Automata

  13. Interface Automata (IA) • Interface automata are suitable for modeling component-based systems name in_cnd ISBN in_us in_cnd? cnd$_price! ISBN? Author! name? in_us? us$_price! us$_price cnd$_price Author

  14. Example ISBN name in_cnd in_us cnd$_price credit_no us$_price in_cnd? cnd$_price! ISBN? ref_no! cnd$_price? credit_no? Author! name? err_no! in_us? us$_price! ref_no err_no us$_price cnd$_price Author

  15. IA Composition ISBN name in_cnd in_us credit_no us$_price cnd$_price in_cnd? cnd$_price! ISBN? ref_no! cnd$_price? credit_no? Author! name? err_no! in_us? us$_price! err_no ref_no us$_price cnd$_price Author name in_cnd credit_no in_us ISBN Author! credit_no? ISBN? err_no! cnd$_price; in_cnd? Author! name? ref_no! credit_no? err_no! Author! ref_no! Author ref_no err_no

  16. IA Composition- Cont’d name in_cnd credit_no in_us ISBN ISBN? in_cnd? Author! name? cnd$_price; ISBN? in_cnd? Author! name? credit_no? credit_no? ISBN? in_cnd? Author! name? err_no! ref_no! err_no! ref_no! ISBN? in_cnd? Author! name? Author ref_no err_no

  17. Illegal States e! b! b? c? d? a? 0’ 3’ 1’ 2’ 0 3 1 2 e! d? (0,0’) (0,3’) (0,1’) (0,2’) a? a? a? a? e! d? (1,3’) (1,0’) (1,1’) (1,2’) b; e! d? (2,2’) (2,0’) (2,3’) (2,1’) c? c? c? c? e! d? (3,0’) (3,3’) (3,1’) (3,2’)

  18. IA Cont’d (helpful environment) a c e! d? (0,0’) (0,1’) (0,2’) a? a? a? e! d? (1,0’) (1,1’) (1,2’) b; (2,3’) c? (3,3’) d e d e d! a! c! e? Environment a c

  19. IA Refinement credit_no us$_price cnd$_price ref_no! cnd$_price? credit_no? Pay err_no! ref_no err_no GenPay refines Pay cnd$_price account_no credit_no us$_price cnd$_price? credit_no? ref_no! GenPay us$_price? ref_no

  20. Outline • Interface Models • Interface Automata • Parameterized Interface Automata

  21. IA is not expressive enough • Actions in IA are atomic elements • Methods/messages/functions are all complex elements consisting of atomic elements • To provide such complex elements we propose a new model

  22. Parameterized Interface Automata (PIA) credit_no us$_price cnd$_price ref_no! pay_in_cnd cnd$_price? credit_no? err_no! ref_no err_no

  23. PIA Cont’d • Each complex action either consists entirely of input/internal or output/internal actions • Each complex action maintains the sequentiality of its consisting simple elements during compositions • An IA is a PIA without complex actions

  24. PIA Cont’d • A PIA can be assumed to be specification of a class and its methods, with all possible orders of execution for such methods • Or, specification of a composite Web service with all scenarios for its operations • PIA can then be used as a tool for top-down design of such systems

  25. PIA Composition ISBN name in_cnd in_us credit_no us$_price cnd$_price in_cnd? cnd$_price! pay_in_cnd ISBN? ref_no! Author! name? cnd$_price? credit_no? err_no! us$_price! in_us? ref_no err_no us$_price cnd$_price Author name in_cnd credit_no in_us ISBN Author! err_no! ISBN? pay_in_cnd in_cnd? ref_no! err_no! cnd$_price; credit_no? Author! name? ref_no! Author ref_no err_no

  26. PIA Composition- Cont’d name in_cnd credit_no in_us ISBN ISBN? in_cnd? Author! name? pay_in_cnd cnd$_price; ISBN? in_cnd? name? credit_no? credit_no? ISBN? in_cnd? Author! name? err_no! ref_no! err_no! ref_no! ISBN? in_cnd? Author! name? Author ref_no err_no

  27. PIA vs. IA name in_cnd credit_no in_us ISBN Author! err_no! ISBN? pay_in_cnd in_cnd? ref_no! err_no! cnd$_price; credit_no? Author! name? ref_no! Author ref_no err_no name in_cnd credit_no in_us ISBN Author! credit_no? ISBN? err_no! cnd$_price; in_cnd? Author! name? ref_no! credit_no? err_no! Author! ref_no! Author ref_no err_no

  28. PIA Refinement credit_no us$_price cnd$_price ref_no! pay_in_cnd Pay Credit_no? cnd$_price? err_no! ref_no err_no credit_no us$_price province cnd$_price account_no pay_in_cnd ref_no! cnd$_price? province? credit_no? GenPay cnd$_price? account_no? err_no! pay_in_cnd_acc ref_no err_no

  29. PIA Is Restrictive ISBN name in_cnd in_us credit_no us$_price cnd$_price in_cnd? cnd$_price! pay_in_cnd ISBN? ref_no! Author! cnd$_price? credit_no? name? err_no! in_us? us$_price! err_no ref_no us$_price cnd$_price Author name in_cnd credit_no in_us ISBN ISBN? Author! err_no! credit_no? in_cnd? cnd$_price; name? ref_no! name? err_no! Author! credit_no? ISBN? ref_no! Author ref_no err_no

  30. Concluding Remarks • PIA is an intuitive model for checking compatibility of component-based (and probably OO) systems • I would like to study and understand how we can decompose interface models into some interesting constituent elements

  31. References • Luca de Alfaro and Thomas A. Henzinger. Interface Automata. In Volker Gruhn, editor, Proceedings of the Joint 8th European Software Engeneering Conference and 9th ACM SIG-SOFT Symposium on the Foundation of Software Engeneering (ESEC/FSE-01), volume 26, 5 of SOFTWARE ENGINEERING NOTES, pages 109-120, New York, September 10-14 2001. ACM Press. • Luca de Alfaro and Thomas A. Henzinger. Interface Theories for Component-Based Design. In Proceedings of the First International Workshop on Embedded Software, volume 2211, pages 148-165. Lecture Notes in Computer Science 2211, Springer-Verlag, 2001. • Shahram Esmaeilsabzali. An Interface Approach to Discovery and Composition ofWeb Services. Master of mathematics, School of Computer Science, University of Waterloo, 200 University Ave. W., Waterloo, Ontario, Canada, N2L 3G1, 06 2004.

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