Modeling and Analysis of Mixed Synchronous/Asynchronous Systems

Practical safety-critical distributed systems must integrate safety critical and non-critical data in a common platform. Safety critical systems almost always consist of isochronous components that have synchronous or asynchronous interface with other components. Many of these systems also support a mix of synchronous and asynchronous interfaces. This report presents a study on the modeling and analysis of asynchronous, synchronous, and mixed synchronous/asynchronous systems. We build on the SAE Architecture Analysis and Design Language (AADL) to capture architectures for analysis. We present preliminary work targeted to capture mixed low- and high-criticality data, as well as real-time properties in a common Model of Computation (MoC). An abstract, but representative, test specimen system was created as the system to be modeled

Error Propagation in a System Model

Embodiments of the present subject matter can enable the analysis of signal value errors for system models. In an example, signal value errors can be propagated through the functional blocks of a system model to analyze possible effects as the signal value errors impact incident functional blocks. This propagation of the errors can be applicable to many models of computation including avionics models, synchronous data flow, and Kahn process networks

Automatic Verification of Component-Based Real-Time CORBA Applications

Distributed real-time embedded (DRE) systems often need to satisfy various time, resource and faulttolerance constraints. To manage the complexity of scheduling these systems many methods use Rate Monotonic Scheduling assuming a time-triggered architecture. This paper presents a method that captures the reactive behavior of complex time- and event-driven systems, can provide simulation runs and can provide exact characterization of timed properties of component-based DRE applications that use the publisher/subscriber communication pattern. We demonstrate our approach on real-time CORBA avionics applications. 1

Model-based Analysis of Distributed Real-time Embedded System Composition

Key challenges in distributed real-time embedded (DRE) system developments include safe composition of system components and mapping the functional specifications onto the target platform. Model-based verification techniques provide a way for the design-time analysis of DRE systems enabling rapid evaluation of design alternatives with respect to given performance measures before committing to a specific platform. This paper introduces a semantic domain for model-based analysis of a general class of DRE systems capturing their key time-based performance measures. We then utilize this semantic domain to develop a verification strategy for preemptive schedulability using available model checking tools. The proposed framework and verification strategy is demonstrated on a mission-critical avionics DRE system case study

Domain-specific Modeling of Power Aware Distributed Real-time Embedded Systems

Abstract. This paper provides two contributions to the research on applying domain-specific modeling languages to distributed real-time embedded (DRE) systems. First, we present the ALDERIS platform-independent visual language for component-based system development. Second, we demonstrate the use of the ALDERIS language on a helicopter autopilot DRE design. The ALDERIS language is based on the concept of platform-based design, and explicitly captures asynchronous event-driven component interactions as well as the underlying platform for the computation. Unlike most modeling languages, ALDERIS has formally defined semantics providing a way for the formal verification of dense real-time properties and energy consumption.

A Conservative Approximation Method for the Verification of Preemptive Scheduling using Timed Automata

This paper presents a conservative approximation method for the real-time verification of asynchronous event-driven distributed systems. This problem is known to be undecidable in the generic setting. The proposed approach is based on composable timed automata models that provide a sufficient condition to determine schedulability. We demonstrate the method on a real-time CORBA avionics design. 1

Performance estimation of distributed real-time embedded systems by discrete-event simulatioins,” EMSOFT

Key challenges in the performance estimation of distributed real-time embedded (DRE) systems include the systematic measurement of coverage by simulations, and the automated generation of directed test vectors. This paper investigates how DRE systems can be represented as discrete event systems (DES) in continuous time, and proposes an automated method for the performance evaluation of such systems. The proposed method also provides a way for the verification of dense time properties for a large class of DRE systems. This approach provides a formal executable model allowing to bridge the gap between simulations and formal verification. Our results show that the proposed DES-based evaluation method can achieve better coverage in large-scale DRE systems than alternative methods