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The following topics are dealt with: real-time networking; data management; multi-resource scheduling; formal methods and specifications; hardware/software boundary; sensor networks; multiprocessor scheduling; and energy awareness
The real-time specification for Java (RTSJ) provides an integrated approach to scheduling periodic threads and monitoring their CPU execution time. It defines a cost enforcement model whereby a periodic thread is suspended when it consumes more CPU time (budget) than it requested. However, the support for this model is optional and it is generally not given by most implementations. Consequently, this...
Temporal correctness is crucial to the dependability of real-time systems. Few methods exist to test for temporal correctness and most existing methods are ad-hoc. A problem with testing real-time applications is the dependency on the execution time and execution order of individual tasks. Thus, the response times for the tasks may be non-deterministic with respect to inputs. Conventional test coverage...
An approach to hardware/software codesign and verification is presented. Hardware and software are modeled with the specification PEARL language, which has its origins in standard multiprocessor PEARL. Its usefulness has been enhanced for hierarchical and asymmetrical multiprocessor system modeling, and by additional parameters for schedulability analysis. It is meant to be a super-layer for programs,...
In this paper, we use networks of UML statechart diagrams to model compositional designs for real-time systems, and present an algorithm for checking networks of statechart diagrams for the scenario-based specifications expressed by UML sequence diagrams with timing constraints. The algorithm is based on investigating the reachability graph of the integer state space of a network of statechart diagrams
We consider the concurrent execution of several applications within a single JVM. In order to have a different GC per application, we introduce and define application-specific memory, building upon the real-time specification for Java (RTSJ) from the real-time Java expert group. The RTSJ memory model imposes strict assignment rules to or from memory areas preventing the creation of dangling pointers...
The Ravenscar-Java profile is defined for high-integrity real-time Java programs. However, it only supports one application at any instance. This paper proposes an extended Ravenscar-Java that supports multiple applications with mixed integrity levels
Source code for real-time control systems often intertwines several concerns such as functionality, data flow, control flow, synchronization, timing, and architectural style. This combination of concerns makes software harder to write correctly, harder to verify, and harder to reuse. This paper proposes an execution architecture that makes such systems more analyzable, verifiable, and reusable by...
Modem real-time programming languages and operating systems provide support for monitoring the amount of CPU time a thread consumes. However, no system in widespread use fully integrates this monitoring with the scheduling facilities. The real-time specification for Java (RTSJ) provides an integrated approach to scheduling periodic threads and monitoring their CPU execution time. It supports a cost...
One of the most powerful features of the real-time specification for Java (RTSJ) is the new memory management model based on scoped memory areas. This model allows programmers to ensure timely reclamation of memory and predictable performance, at the cost of an unfamiliar programming model. We report on experience using and implementing scoped memory areas. Our contribution is twofold: (i) we give...
The Real-Time Specification for Java is now about two years old. It has been implemented, formed the basis for research and used in serious applications. Some strengths and weaknesses are becoming clear. This paper reviews the current status of the specification, outlines the challenges ahead and discusses areas where there is likely to be future design work
Extensions like the real-time specification for Java (RTSJ) enable the use of Java in more and more time-critical application domains. The RTSJ enables the development of realtime code in Java even though a classical garbage collector causes unpredictable pauses to non-realtime code. We give an overview of how a modern realtime garbage collectors operates. It presents the impact the presence of such...
The following topics are dealt with: distributed real-time systems; real-time Java; formal specification; UML; systems modelling; middleware; distributed databases; Web services; program testing; formal verification; scheduling; memory management; object-oriented computing
The author reviews the literature on the use of garbage collection in real-time systems. The author concentrates on hard real-time systems, where we ideally construct mathematical proofs of correctness and of timing properties. In particular, the author examines the interaction of overheads imposed on mutator operations by garbage collection algorithms on worst-case execution time analyses of real-time...
Symbolic model checking has been used to formally verify specifications of secure transactions in a system for ebXML-based business-to-business. The fundamental principles behind symbolic model checking are presented along with techniques used to model mutual exclusion of processes and atomic transactions. The computational resources required to check the example process are presented, and faults...
This paper intends to contribute to efforts for standardising ECBS process and information models and ECBS architectures by exploring these ECBS constituents with respect to the design and development of heterogeneous systems like micro-systems. These highly-integrated systems are usually embedded into larger systems like cars and consist of many different mechanical or electrical elements. This diversity...
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