A Profile for Safety Critical Java

Concurrency and Computation

Dalsgaard

Hansen

et al. 2016

Self Cite

Phone +45 4525 3351 compute@compute.dtu.dk www.compute.dtu.dk IMM-PhD-2014-340 Summary (English) Safety-critical systems are real-time systems whose failure can have severe or catastrophic consequences, possibly endangering human life. Many safety-critical systems incorporate embedded computers used to control different tasks. Software running on safety-critical systems needs to be certified before its deployment and the most time-consuming step of this process is the testing and verification phase. Due to the increasing complexity in safety-critical systems there is a need for new technologies that can facilitate testing and verification activities.The safety-critical specification for Java aims at providing a reduced set of the Java programming language that can be used for systems that need to be certified at the highest levels of criticality. Safety-critical Java (SCJ) restricts how a developer can structure an application by providing a specific programming model and by restricting the set of methods and libraries that can be used. Furthermore, its memory model do not use a garbage-collected heap but scoped memories.In this thesis we examine the use of the SCJ specification through an implementation in a time-predictable, FPGA-based Java processor. The specification is now in a mature state and with our implementation we have proved its feasibility in an embedded platform. Moreover, we have explored how simple hardware extensions can reduce the execution time of time-critical operations required by the SCJ specification.The scoped memory model used in SCJ is perhaps one of its most difficult features to use correctly. Therefore, in this work we have also studied practical aspects of its usage by developing scoped memory use patterns and reusable libraries aiming at facilitating the development of complex software systems.ii Summary (Danish)Sikkerhedskritiske systemer er realtidssystemer. Hvis sådanne systemer fejler, kan det have alvorlige eller katastrofale konsekvenser, muligvis livsfarlige konsekvenser. Mange sikkerhedskritiske systemer inkorporerer embeddede computere, som bruges til at kontrollere forskellige opgaver. Software, som kører på sikkerhedskritiske systemer, skal certificeres, før softwaren udrulles, og det mest tidskraevende skridt i denne proces er test-og verifikationsfasen. På grund af den stigende kompleksitet i sikkerhedskritiske systemer er der behov for nye teknologier til at facilitere test-og verifikationsaktiviteter.Den sikkerhedskritiske specifikation for Java har til formål at levere en reduceret udgave af Java-programmeringssproget, som kan bruges til systemer, der skal kunne certificeres på de højeste kritikalitetsniveauer. Safety Critical Java (SCJ) begraenser, hvordan en udvikler kan strukturere en applikation, ved at levere en specifik programmeringsmodel og ved at begraense de metoder og biblioteker, som kan anvendes. Derudover benytter hukommelsesmodellen i SCJ ikke en heap, der er garbage-collected, men afgraensede hukommelser.I denne afhandling undersøger vi brugen a...

Section: Lessons Learnedmentioning

confidence: 99%

Safety‐critical Java for embedded systems

Concurrency and Computation

Dalsgaard

Hansen

et al. 2016

Self Cite

“…Later proposals for a safetycritical Java profile argue for an API that is independent of the RTSJ [33,43]. The argument is that all approaches that inherit from RTSJ classes introduce additional complexity.…”

Section: Related Workmentioning

confidence: 99%

“…Instead of using the classes defined by the SCJ profile, their implementation is based on a profile called Predictable Java (PJ). PJ is a Java profile suitable for the development of high-integrity real-time embedded systems that builds on the ideas of [15,26,43] and [46]. The profile is based on the execution of event handlers grouped in missions, which in turn are also considered event handlers.…”

Section: Related Workmentioning

confidence: 99%

See 1 more Smart Citation

Certifiable Java for Embedded Systems

Proceedings of the 12th International Workshop on Java Technologies for Real-Time and Embedded Systems

Dalsgaard

Hansen

et al. 2014

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The Certifiable Java for Embedded Systems (CJ4ES) project aimed to develop a prototype development environment and platform for safety-critical software for embedded applications. There are three core constituents: A profile of the Java programming language that is tailored for safety-critical applications, a predictable Java processor built with FPGA technology, and an Eclipse based application development environment that binds the profile and the platform together and provides analyses that help to provide evidence that can be used as part of a safety case. This paper summarizes key contributions within these areas during the three-year project period. In the conclusion the overall result of the project is assessed.

“…In [35] a profile for safety-critical Java (SCJ) is defined. SCJ is also an evolving standard under the Java Community Process (JSR 302) [16] for future safety-critical systems.…”

Section: Safety Critical Javamentioning

confidence: 99%

Scheduling of hard real-time garbage collection

2010

Real-Time Syst

Self Cite

Automatic memory management or garbage collection greatly simplifies development of large systems. However, garbage collection is usually not used in real-time systems due to the unpredictable temporal behavior of current implementations of a garbage collector. In this paper we propose a real-time garbage collector that can be scheduled like a normal real-time thread with a deadline monotonic assigned priority. We provide an upper bound for the collector period so that the application threads will never run out of memory. Furthermore, we show that the restricted execution model of the Safety Critical Java standard simplifies root scanning and reduces copying of static data. Our proposal has been implemented and evaluated in the context of the Java processor JOP.