High-level real-time programming in Java

Second Workshop on …, 2005

The region-based memory model of The Real-time Specification for Java (RTSJ) is quite rigid, and it complicates the development of reusable predictable software for large-scale systems. In this paper, we propose an extension to the region model of the RTSJ called AGCMemory (Acyclic Garbage Collected Memory). This extension enables the destruction of floating garbage created during the execution of Java methods. The integration in the memory model of the RTSJ and the new required runtime barriers are addressed.

2000

Real-time programming is simply a necessity in many fields of application and specific real-time operating systems exist in order to fulfill the necessity of users to have time determinism in their applications. Anyway, often time constraints are not so hard and it is possible to identify hard and soft real-time applications, but time determinism keeps on being the mandatory requirement. The aim of this paper is that of describing the results of an activity devoted to investigate the possibility of real-time programming in a Java environment. A package has been developed in order to give a Java platform real-time capabilities of scheduling threads with time-based policies or by priority and events. A set of methods for threads to communicate through queues, messages, and mailboxes has been developed too.

Lecture Notes in Computer Science, 2006

Real-time systems are notoriously difficult to design and implement, and, as many real-time problems are safety-critical, their solutions must be reliable as well as efficient and correct. While higher-level programming models (such as the Real-Time Specification for Java) permit real-time programmers to use language features that most programmers take for granted (objects, type checking, dynamic dispatch, and memory safety) the compromises required for real-time execution, especially concerning memory allocation, can create as many problems as they solve. This paper presents Scoped Types and Aspects for Real-Time Systems (STARS) a novel programming model for real-time systems. Scoped Types give programmers a clear model of their programs' memory use, and, being statically checkable, prevent the run-time memory errors that bedevil models such as RTSJ. Our Aspects build on Scoped Types guarantees so that Real-Time concerns can be completely separated from applications' base code. Adopting the integrated Scoped Types and Aspects approach can significantly improve both the quality and performance of a real-time Java systems, resulting in simpler systems that are reliable, efficient, and correct.

2012

2007

In the authors' first report on the Sun Java Real-Time System (RTS), they concluded that it is preferable to use real-time Java threads that use heap memory rather than no-heap real-time threads (NHRTTs) for the Global Integrated Fire Control System (GIFC) due to the difficulty of ...

Eighth IEEE International Symposium on Object-Oriented Real-Time Distributed Computing (ISORC'05), 2000

One of the problems with Java for real-time systems is the unpredictable behavior of garbage collection (GC). GC introduces unexpected load and causes undesirable delays for real-time applications. In this paper, we propose a technique that reduces and bounds the memory requirements for real-time Java programs. This technique can eliminate or reduce the need for GC and allows for a more predictable execution behavior and efficient utilization of the available memory. A theoretical model is presented and a number of benchmark tests are used to evaluate this technique in PERC, NewMonics' realtime JVM, and Sun's JVM. The results show that in some cases GC can be eliminated and an application's execution time decreases and becomes more predictable.

2006

The object-oriented paradigm has become popular over the last years due to its characteristics that help managing the complexity in computer systems design. This feature also attracted the embedded systems community, as today's embedded systems need to cope with several complex functionalities as well as timing, power, and area restrictions. Such scenario has promoted the use of the Java language and its real-time extension (RTSJ) for embedded real-time systems design. Nevertheless, the RTSJ was not primarily designed to be used within the embedded domain. This paper presents an approach to optimize the use of the RTSJ for the development of embedded real-time systems. Firstly, it describes how to design real-time embedded applications using an API based on RTSJ. Secondly, it shows how the generated code is optimized to cope with the tight resources available, without interfering in the mandatory timing predictability of the generated system. Finally it discusses an approach to synthesize the applications on top of affordable FPGAs. The approach used to synthesize the embedded real-time system ensures a bounded timing behavior of the object-oriented aspects of the application, like the polymorphism mechanism and read/write access to object's data fields.

Real-Time Systems, 2007

Real-time systems are notoriously difficult to design and implement, and, as many real-time problems are safety-critical, their solutions must be reliable as well as efficient and correct. While higher-level programming models (such as the Real-Time Specification for Java) permit real-time programmers to use language features that most programmers take for granted (objects, type checking, dynamic dispatch, and memory safety) the compromises required for real-time execution, especially concerning memory allocation, can create as many problems as they solve. This paper presents Scoped Types and Aspects for Real-Time Systems (STARS) a novel programming model for real-time systems. Scoped Types give programmers a clear model of their programs' memory use, and, being statically checkable, prevent the run-time memory errors that bedevil the RTSJ. Adopting the integrated Scoped Types and Aspects approach can significantly improve both the quality and performance of a real-time Java systems, resulting in simpler systems that are reliable, efficient, and correct.

Lecture Notes in Computer Science, 2008

The Real-Time Specification for Java (RTSJ) is becoming a popular choice in the world of real-time and embedded programming. However, RTSJ introduces many non-intuitive rules and restrictions which prevent its wide adoption. Moreover, current state-of-theart frameworks usually fail to alleviate the development process into higher layers of the software development life-cycle. In this paper we extend our philosophy that RTSJ concepts need to be considered at early stages of software development, postulated in our prior work [2], in a framework that provides continuum between the design and implementation process. A component model designed specially for RTSJ serves here as a cornerstone. As the first contribution of this work, we propose a development process where RTSJ concepts are manipulated independently of functional aspects. Second, we mitigate complexities of RTSJ-development by automatically generating execution infrastructure where real-time concerns are transparently managed. We thus allow developers to create systems for variously constrained real-time and embedded environments. Performed benchmarks show that the overhead of the framework is minimal in comparison to manually written object-oriented applications, while providing more extensive functionality. Finally, the framework is designed with the stress on dynamic adaptability of target systems, a property we envisage as a fundamental in an upcoming era of massively developed real-time systems.

A Practitioner's Handbook for Real-Time Analysis, by Mark H. KLEIN et al.; Kluwer Academic Publishers; Boston, MA, USA; 1993; xiii + 694 pp.; $95; ISBN: 0-7923-9361-9 iRAT -The introspect Real-Time Analysis Tool,