Abstract

Abstract

Abstract

Abstract
Concurrent programming is dominated by thread based solutions with lock based critical sections. Careful attention has to be paid to avoid race and deadlock conditions. Real-Time for The Masses (RTFM) takes an alternative language approach, introducing tasks and named critical sections (via resources) natively in the RTFM-core language. RTFM-core programs can be compiled to native C-code, and efficiently executed onto single-core platforms under the Stack Resource Policy (SRP) by the RTFM-kernel. In this paper we formally define the well-formedness criteria for SRP based resource management, and develop a certified (formally proven) implementation of the corresponding compilation from nested critical sections of the input RTFM-core program to a resulting flat sequence of primitive operations and scheduling primitives. Moreover we formalise the properties for resource ceilings under SRP and develop a certified algorithm for their computation. The feasibility of the described approach is shown through the adoption of the Why3 platform, which allows the necessary verification conditions to be automatically generated and discharged through a variety of automatic external SMT-solvers and interactive theorem provers. Moreover, Why3 supports the extraction of certified Ocaml code for proven implementations in WhyML. As a proof of concept the certified extracted development is demonstrated on an example system. © 2016 IEEE.

Abstract

Abstract
The IEC 61499 standard proposes an event driven execution model for component based (in terms of Function Blocks), distributed industrial automation applications. However, the standard provides only an informal execution semantics, thus in consequence behavior and correctness relies on the design decisions made by the tool vendor. In this paper we present the formalization of a subset of the IEC 61499 standard in order to provide an underpinning for the static verification of Function Block models by means of deductive reasoning. Specifically, we contribute by addressing verification at the component, algorithm, and ECC levels. From Function Block descriptions, enriched with formal contracts, we show that correctness of component compositions, as well as functional and transitional behavior can be ensured. Feasibility of the approach is demonstrated by manually encoding a set of representative use-cases in WhyML, for which the verification conditions are automatically derived (through the Why3 platform) and discharged (using automatic SMT-based solvers). Furthermore, we discuss opportunities and challenges towards deriving certified executables for IEC 61499 models. © 2016 IEEE.