Abstract. The Real-time Specification for Java (RTSJ) introduced a range of language features for explicit memory management. While the RTSJ gives programmers fine control over memory use and allows linear allocation and constant time deallocation, the RTSJ relies upon dynamic runtime checks for safety making it unsuitable for safety critical applications. We introduce ScopeJ, a statically typed, multi-threaded, object calculus in which scopes are first class constructs. Scopes reify allocation contexts and provide a safe alternative to automatic memory management. Safety is the result of our use of an ownership type system that enforces a topology on run-time patterns of references. ScopeJ’s type system is novel in that ownership annotations are implicit. This substantially reduces the burden for developers, thus increasing the likelihood of adoption. The notion of implicit ownership is particularly appealing when combined with pluggable type systems, as one can apply different type constraints to components depending on the requirements. In related work we have demonstrated the usefulness of our approach in different applications. 1

The Real-time Specification for Java extends the Java platform

Real-time Java is quickly emerging as a platform for building safety-critical embedded systems. The real-time variants of Java, including [8, 15], are attractive alternatives to Ada and C since they provide a cleaner, simpler, and safer programming model. Unfortunately, current real-time Java implementations have trouble scaling down to very hard real-time embedded settings, where memory is scarce and processing power is limited. In this paper, we describe the architecture of the Fiji VM, which enables vanilla Java applications to run in very hard environments, including booting on bare hardware with only very rudimentary operating system support. We also show that our minimalistic approach delivers comparable performance to that of server-class production Java Virtual Machine implementations. 1.

Abstract—Real-time Java is emerging as a platform for building mission-critical embedded systems. The real-time variants of Java, including [3], [4], are attractive alternatives to Ada and C as they provide a cleaner, simpler, and safer programming model. Unfortunately, current real-time Java implementations have trouble scaling down to very hard realtime embedded settings, where memory is scarce and processing power is limited. In this poster, we describe a new real-time Java implementation, the fVM, intended for use in avionics, space, and cyber-physical systems. 1