Safety-Critical Java: : level 2 in practice

Safety-Critical Java (SCJ) is a profile of the Real-Time Specification for Java that brings to the safety-critical industry the possibility of using Java. SCJ defines three compliance levels: Level 0, Level 1 and Level 2. The SCJ specification is clear on what constitutes a Level 2 application in terms of its use of the defined API but not the occasions on which it should be used. This paper broadly classifies the features that are only available at Level 2 into three groups: nested mission sequencers, managed threads and global scheduling across multiple processors. We explore the first two groups to elicit programming requirements that they support. We identify several areas where the SCJ specification needs modifications to support these requirements fully; these include the following: support for terminating managed threads, the ability to set a deadline on the transition between missions and augmentation of the mission sequencer concept to support composibility of timing constraints. We also propose simplifications to the termination protocol of missions and their mission sequencers. To illustrate the benefit of our changes, we present excerpts from a formal model of SCJ Level 2 written in Circus, a state-rich process algebra for refinement. Copyright © 2016 John Wiley & Sons, Ltd

Mobile Resource Guarantees for Smart Devices

Abstract. We present the Mobile Resource Guarantees framework: a system for ensuring that downloaded programs are free from run-time violations of resource bounds. Certificates are attached to code in the form of efficiently checkable proofs of resource bounds; in contrast to cryptographic certificates of code origin, these are independent of trust networks. A novel programming language with resource constraints encoded in function types is used to streamline the generation of proofs of resource usage.

SCJ-Circus: specification and refinement of Safety-Critical Java programs

Safety-Critical Java (SCJ) is a version of Java for real-time, embedded, safety-critical applications. It supports certification via abstractions that enforce a particular program architecture, with controlled concurrency and memory models. SCJ is an Open Group standard, with a reference implementation, but little support for reasoning. Here, we present SCJ-Circus, a refinement notation for specification and verification of low-level models of SCJ programs. SCJ-Circus is part of the Circus family of state-rich process algebras: it includes the Circus constructs for modelling of sequential and concurrent behaviour based on Z and CSP, and the real-time and object-oriented extensions of Circus, in addition to the SCJ abstractions. We present the syntax of SCJ-Circus and its semantics, defined by mapping SCJ-Circus constructs to those of Circus. We also detail a refinement strategy that takes a Circus design that adheres to a multiprocessor cyclic executive pattern and produces an SCJ program design, described in SCJ-Circus. Finally, we show how this refinement strategy can be extended for more complex program architectures

Realising intelligent virtual design

This paper presents a vision and focus for the CAD Centre research: the Intelligent Design Assistant (IDA). The vision is based upon the assumption that the human and computer can operate symbiotically, with the computer providing support for the human within the design process. Recently however the focus has been towards the development of integrated design platforms that provide general support irrespective of the domain, to a number of distributed collaborative designers. This is illustrated within the successfully completed Virtual Reality Ship (VRS) virtual platform, and the challenges are discussed further within the NECTISE, SAFEDOR and VIRTUE projects

Realising intelligent virtual design

This paper presents a vision and focus for the CAD Centre research: the Intelligent Design Assistant (IDA). The vision is based upon the assumption that the human and computer can operate symbiotically, with the computer providing support for the human within the design process. Recently however the focus has been towards the development of integrated design platforms that provide general support irrespective of the domain, to a number of distributed collaborative designers. This is illustrated within the successfully completed Virtual Reality Ship (VRS) virtual platform, and the challenges are discussed further within the NECTISE, SAFEDOR and VIRTUE projects

SCJ-Circus : a refinement-oriented formal notation for Safety-Critical Java

Safety-Critical Java (SCJ) is a version of Java whose goal is to support the development of real-time, embedded, safety-critical software. In particular, SCJ supports certification of such software by introducing abstractions that enforce a simpler architecture, and simpler concurrency and memory models. In this paper, we present SCJ-Circus, a refinement-oriented formal notation that supports the specification and verification of low-level programming models that include the new abstractions introduced by SCJ. SCJ-Circus is part of the family of state-rich process algebra Circus, as such, SCJ-Circus includes the Circus constructs for modelling sequential and concurrent behaviour, real-time and object orientation. We present here the syntax and semantics of SCJ-Circus, which is defined by mapping SCJ-Circus constructs to those of standard Circus. This is based on an existing approach for modelling SCJ programs. We also extend an existing Circus-based refinement strategy that targets SCJ programs to account for the generation of SCJ-Circus models close to implementations in SCJ