C. Compositional Design and Verification of Component-Based Information Systems Jan Martijn van der Werf

Organizations cooperate Bob Charley Alice “Who-knows-who” not transitive! Dave

Organizations deliver services Bob Charley Alice Dave

Component-based information system Process Data Process Data Process Data Process Data Process Data Process Data

Verification vs. design Verification: Go and do what you want, check when finished Correctness by design: Follow my rules, and it is correct vs.

Compositional verification of soundness Components form a service tree Components only know their direct neighbors B C E D = soundness of component = condition on communicating pair of components A F

Compositional verification of soundness

Soundness not sufficient for pairwise verification!

Compositional design: refinement rules! Stepwise refinement Each step preserves soundness Refinement rules: Within component Outsourcing Over components

Process + Data = Prototype + +

Compositional design and verification of Component-based information systems Framework for component-based information systems Compositional verification of interaction Compositional design of interaction Petri nets extended with data Message passing Data transactions Process + data  prototype Re-engineering by process mining

C Compositional Design and Verification of Component-Based Information Systems Jan Martijn van der Werf

Soundness: always possible to finish properly (disregarding interfaces) Components and their composition a b c d e a b c d e H I GG

Correctness by design Refinement within a component

Correctness by design Refinement over components

Correctness by design Outsource refinement

Sufficient conditions for

Sufficient conditions for soundness BB+C B B Identical communication: B+C behaves like B on interface with A Alternating communication block: B+C has same communication blocks as B Elastic communication: B+C may send earlier and receive later than B