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Modeling Component- -based based Modeling Component Systems in BIP Systems in BIP ETR 2007 ETR 2007 Nantes, Sept. 2007 Nantes, Sept. 2007 Joseph Sifakis VERIMAG sifakis@imag.fr In collaboration with G. Goessler (INRIA), A. Basu, M. Bozga, H. Nguyen (Verimag) 1 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

Component- -based construction based construction – – Objectives Objectives Component Develop a rigorous and general basis for real-time system design and implementation • Concept of component and associated composition operators for incremental description and correctness by construction • Concept for real-time architecture encompassing heterogeneity, paradigms and styles of computation e.g. � Synchronous vs. asynchronous execution � Event driven vs. time driven computation � Distributed vs. centralized execution • Automated support for component integration and generation of glue code meeting given requirements 2 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

Approches involving components Approches involving components • Theory such as process algebras and automata • SW Component frameworks, such as � Coordination languages extensions of programming languages : Linda, Javaspaces, TSpaces, Concurrent Fortran, NesC, BPEL � Middleware e.g. Corba, Javabeans, .NET � Software development environments: PCTE, SWbus, Softbench, Eclipse • System modeling languages: SystemC, Statecharts, UML, Simulink/Stateflow, Metropolis, Ptolemy • Architecture Description Languages focusing on non-functional aspects e.g. AADL Lack of • frameworks treating interactions and system architecture as first class entities that can be composed and analyzed (usually, interaction by method call) • rigorous models for behavior and in particular aspects related to time and resources. 3 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

Sources of heterogeneity heterogeneity [Henzinger&Sifakis FM06] Sources of [Henzinger&Sifakis FM06] Heterogeneity of interaction • Atomic or non atomic • Rendezvous or Broadcast • Binary or n-ary Heterogeneity of execution • Synchronous execution • Asynchronous execution • Combinations of them Heterogeneity of abstraction e.g. granularity of execution 4 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

Sources of Heterogeneity Sources of Heterogeneity - - Example Example A: Atomic interaction R: Rendezvous B: Broadcast Java SDL UML UML Asynchronous Computation Lotos CSP A R nonA R A B nonA B Synchronous Computation Matlab/Simulink VHDL, Statecharts, Synchronous languages 5 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

Overview Overview • About component-based construction • Basic Concepts • Interaction modeling • Priority modeling • Implementation • Modeling systems in BIP • Discussion 6 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

Component- -based Construction: The Problem based Construction: The Problem Component Pb: Build a component C satisfying a given property P, from • C 0 a set of atomic components • GL ={gl 1 , …, gl i , …} a set of glue operators on components gl12 gl1 gl2 sat P c 2 c’ 2 c 1 c’ 1 Glue operators • model mechanisms used for communication and control such as protocols, schedulers, buses • restrict the behavior of their arguments, that is the projection of the behavior of gl(C 1 ,C 2 ,.,C n ) on actions of C 1 is contained in the behavior of C 1 7 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

Component- -based Construction based Construction: : Formal Formal Framework Framework Component Operational Semantics: the meaning of a compound component is an atomic component gl B B 1 B 2 B n Operational Semantics Algebraic framework: • Components are terms of an algebra of terms ( C , ≅ ) generated from C 0 by using operators from GL • ≅ is a congruence compatible with operational semantics 8 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

Component- -based Construction based Construction: : Constructivity Constructivity – – Incremental Incremental description description Component 1. Decomposition gl1 gl C 1 gl2 ≅ C 1 C 2 C n C 2 C n 2. Flattening gl2 gl gl1 ≅ c 1 c’ 1 c 2 c’ 2 c 2 c’ 2 c 1 c’ 1 Flattening can be achieved by introducing an idempotent operation ⊕ such that (GL, ⊕ ) is a commutative monoid and gl(gl’( C 1 ,C 2 ,.., C n )) ≅ gl ⊕ gl’( C 1 ,C 2 ,.., C n ) 9 J. Sifakis Modeling Component- J. Sifakis Modeling Component -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

Component- Component -based Construction based Construction: : Constructivity Constructivity – – Compositionality Compositionality Build correct systems from correct components: rules for ☺ gl proving global properties from ☺ ☺ properties of individual components gl ~ ~ c i sat P i implies ∀ gl ∃ gl sat gl(P 1 , ..,P n ) c 1 c n We need compositionality results about preservation of progress properties such as deadlock-freedom and liveness and extra-functional properties 10 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

Component- Component -based Construction based Construction: : Constructivity Constructivity – – Composability Composability Make the new without gl gl ☺ � breaking the old: Rules ☺ ☺ guaranteeing non interference of solutions gl gl’ sat P’ sat P and c 1 c n c 1 c n gl ⊕ gl’ sat P ∧ P’ implies c 1 c n Property stability phenomena are poorly understood. We need composability results e.g. feature interaction in middleware, composability of scheduling algorithms, theory for reconfigurable systems 11 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

Overview Overview • About component-based construction • Basic Concepts • Interaction modeling • Priority modeling • Implementation • Modeling systems in BIP • Discussion 12 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

BIP: Basic Concepts BIP: Basic Concepts Layered component model Priorities (Memoryless Controller) Interactions (Structured Connectors) B E H A V I O R Composition (incremental description) PR1 ⊕ PR2 ⊕ PR12 PR1 PR2 IN1 ⊗ IN2 ⊗ IN12 || IN1 IN2 13 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

BIP: Basic Concepts BIP: Basic Concepts Priorities: ∅ Interactions: sr1r2r3 s r1 r2 r3 r1 r2 r3 s Sender Receiver1 Receiver2 Receiver3 Rendezvous 14 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

BIP: Basic Concepts BIP: Basic Concepts Priorities: x 〈 xy for x,y=interactions Interactions: s, sr1, sr2, sr3, sr1r2, sr2r3, sr1r3, sr1r2r3 s r1 r2 r3 r1 r2 r3 s Sender Receiver1 Receiver2 Receiver3 Broadcast 15 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

BIP: Basic Concepts BIP: Basic Concepts Priorities: x 〈 xy for x,y=interactions Interactions: s, sr1r2r3 s r1 r2 r3 r1 r2 r3 s Sender Receiver1 Receiver2 Receiver3 Atomic Broadcast 16 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007

BIP: Basic Concepts BIP: Basic Concepts Priorities: x 〈 xy for x,y=interactions Interactions: s, sr1, sr1r2, sr1r2r3 s r1 r2 r3 r1 r2 r3 s Sender Receiver1 Receiver2 Receiver3 Causal Chain 17 J. Sifakis Modeling Component J. Sifakis Modeling Component- -based Systems in BIP based Systems in BIP ETR 2007 Nantes Sept. 2007 ETR 2007 Nantes Sept. 2007