The Safety-Critical Java Mission Model: A Formal Account

Zeyda, Frank; Cavalcanti, Ana; Wellings, Andy

doi:10.1007/978-3-642-24559-6_6

Cited by 7 publications

(5 citation statements)

References 12 publications

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“…Our future work involves further evaluation of the extent to which a sporadic server can be implemented using the approach given in Section 4.3, and the development of libraries that support the various release patterns for managed threads identified in Section 3. In another line of future work, we will define a semantics for SCJ Level 2 programs following the lines of the approach adopted in [25] for Level 1 programs.…”

Section: Discussionmentioning

confidence: 99%

Safety-critical Java level 2

Wellings

Luckcuck

Cavalcanti

2013

Proceedings of the 11th International Workshop on Java Technologies for Real-Time and Embedded Systems

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Safety Critical Java defines three compliance levels: Level 0, Level 1 and Level 2. Applications that can be scheduled using cyclic-executive techniques can be implemented at Level 0. Applications that can use simple analysable fixed-priority scheduling can be implemented at Level 1. However, Level 2 also targets fixed-priority scheduling, so this cannot be used to decide whether to use Level 1 or 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. Hence, it is not clear what application requirements dictate a Level 2 solution. This paper broadly classifies the features that exist only at Level 2 into three groups: support for nested mission sequencers, support for managed threads, including the use of the Object.wait, Object.notify, HighResolutionTime. waitForObject and Services.delay methods, and support for global scheduling across multiple processors. In this paper we explore the first two groups to derive possible programming requirements that each group of features support. We identify several areas where the specification needs modifications in order to support fully these derived requirements. These include 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.

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Section: Discussionmentioning

confidence: 99%

Safety-critical Java level 2

Wellings

Luckcuck

Cavalcanti

2013

Proceedings of the 11th International Workshop on Java Technologies for Real-Time and Embedded Systems

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“…To conclude, in the previous sections we have examined in detail the construction of a formal model for an SCJ program, elaborating and refining our account in [37]. In particular, we have unified the treatment of behavioural and data aspects by way of the general pattern in Fig.…”

Section: Data Objectsmentioning

confidence: 99%

“…In comparison to our previous work [37], here we elaborate and make precise our modelling approach and formalise its construction. We also modularise and, in several places, simplify the framework model, which captures the generic behaviour of the SCJ paradigm.…”

Section: Introductionmentioning

confidence: 99%

Circus Models for Safety-Critical Java Programs

Zeyda¹,

Lalkhumsanga²,

Cavalcanti³

et al. 2013

The Computer Journal

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Safety-Critical Java (SCJ) is a restriction of the Real-Time Specification for Java to support the development and certification of safety-critical applications. The SCJ technology specification is the result of an international effort from industry and academia. In this paper, we present a formalisation of the SCJ Level 1 execution model, formalise a translation strategy from SCJ into a refinement notation, and describe a tool that largely automates the generation of the formal models. Our modelling language is part of the Circus family; at the core, we have Z, CSP, and Morgan's calculus, but we also use object-oriented and timed constructs from the OhCircus and Circus Time variants. Our work is an essential ingredient for the development of refinement-based reasoning techniques for SCJ.

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“…Our previous work focused on complementing the informal account of SCJ [The11] with a formal model of SCJ's mission-based execution paradigm [ZCW11] and memory model [CWW11a]. Our modelling notation is a combination of languages from the Circus family [CSW03,CSW05,SCJS10], specifically tailored for state-rich reactive systems with the addition of discrete time, object orientation, and object references.…”

Section: Introductionmentioning

confidence: 99%

Laws of mission-based programming

Zeyda

Cavalcanti

2015

Form. Asp. Comput.

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Safety-Critical Java (SCJ) is a recent technology that changes the execution and memory model of Java in such a way that applications can be statically analysed and certified for their real-time properties and safe use of memory. Our interest is in the development of comprehensive and sound techniques for the formal specification, refinement, design, and implementation of SCJ programs, using a correct-by-construction approach. As part of this work, we present here an account of laws and patterns that are of general use for the refinement of SCJ mission specifications into designs of parallel handlers, as they are used in the SCJ programming paradigm. Our refinement notation is a combination of languages from the Circus family, supporting state-rich reactive models with the addition of class objects and real-time properties. Starting from a sequential and centralised Circus specification, our laws permit refinement into Circus models of SCJ program designs. Automation and proof of the refinement laws is examined here, too. Our work is an important step towards eliciting laws of programming for SCJ and fits into a refinement strategy that we have developed previously to derive SCJ programs from specifications in a rigorous manner.

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The Safety-Critical Java Mission Model: A Formal Account

Cited by 7 publications

References 12 publications

Safety-critical Java level 2

Safety-critical Java level 2

Circus Models for Safety-Critical Java Programs

Laws of mission-based programming

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