Safety-Critical Java: The Mission Approach

Abstract

Safety-Critical Java is designed to simplify the runtime environment and code generation model for safety-critical applications compared with conventional Java, as well as improve the reuse and modular composability of independently developed software components and their corresponding certification artifacts. While the conventional object-oriented abstractions provided by the Java language already enable strong separation of concerns for passive components such as subroutines and data structures, safety-critical Java’s Mission abstraction generalizes these encapsulation benefits to the domain of active software components.Example active components that can be built as a Mission include device drivers, network communication stacks, plotting of RADAR and SONAR data, track management of RADAR and SONAR plots, and implementation of graphic user interfaces. These various active software components will likely be reused, reconfigured, and combined in different ways for different applications. Each safety-critical mission is comprised of one or more logical threads of execution which are generally structured as a set of periodic event handlers, asynchronous event handlers, and no-heap realtime threads.The Safety-Critical Java specification enforces strong separation of concerns between independently developed missions. And outer-nested missions are never allowed to access the data contained within inner-nested missions. A safety-critical Java application consists of one or more missions running in sequence or concurrently. This chapter introduces the concept of Safety-Critical Java Missions and motivates their use as a tool for software engineering abstraction.