Kelvin Nilsen

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Address: Alpine, Utah, United States

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Aalborg University

Northeastern University

Vaclav Cechticky

Valérie Issarny

Walter Binder

Athanasios Stratikopoulos

Raju Pandey

Patrick Bridges

University of New Mexico

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Papers by Kelvin Nilsen

Adding Real-Time Capabilities to Java Through extensive experimentation, developers somehow find the right combination of parameters to maximize cost, performance, and compliance with real-time constraints

According to Sun, the reason it's so restrictive regarding use of the Java trademark is to assure... more

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Achieving high performance and hard real-time determinism with real-time Java

Early experience demonstrates that "real-time Java" as characterized by the RTSJ: (1) I... more Early experience demonstrates that "real-time Java" as characterized by the RTSJ: (1) Is able to match latency and jitter of C and C++; (2) Requires much more CPU and memory resources than C and C++; (3) Is much more difficult to develop and maintain code than main-stream Java. This talk describes real-time Java disciplines that significantly improve the efficiency, maintainability, and scalability of real-time Java code. (13 pages)

Session details: Real-time garbage collection

Java Technologies for Real-time and Embedded Systems, Sep 26, 2007

Garbage collection of strings and linked data structures in real time

Software - Practice and Experience, Jul 1, 1988

Modern high-level languages frequently need to collect garbage not only from regions of linked st... more Modern high-level languages frequently need to collect garbage not only from regions of linked structures similar to LISP's dotted pairs, but also from string regions where data is organized as an array of characters. Some characteristics of string regions that make garbage collection particularly difficult are as follows: multiple pointers to the same characters within the array are allowed and encouraged; all possible character values are legitimate as data, so it is not possible to 'mark' a string by overwriting with a reserved character; and a character is generally much smaller than a pointer, so it is not possible to overwrite a single character value with a forwarding pointer to a new location for a particular string. This paper describes the addition of certain information to a string descriptor and enhancements to existing copying garbage collection algorithms that permit linked data structures and strings to be allocated and garbage collected from a shared region of memory in real time. This algorithm is real-time in the sense that the time required for allocation of each basic unit of memory is bounded by a constant. An analysis of performance is reported, and comparisons are made with traditional garbage collection.

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Real-time is no longer a small specialized niche

... kelvin @ cs.iastate.edu ... Over the years, the mainstream and real-time commu-nities have di... more

Unification of Safety-Critical Java

HAL (Le Centre pour la Communication Scientifique Directe), Feb 1, 2012

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Proceedings / Second IEEE International Conference on Engineering of Complex Computer Systems : held jointly with 6th CSESAW [Complex Systems Engineering Synthesis and Assessment Technology Workshop], 4th IEEE RTAW [Workshop on Real-Time Applications], and SES '96 [IEEE Forum on Software Engineer...

IEEE Computer Soc. Press, 1996

Session details: Real-time JVM implementation

Proceedings of the 7th International Workshop on Java Technologies for Real-Time and Embedded Systems

Reliable real-time garbage collection of C++

Computing Systems, Sep 20, 1994

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

Welcome to the 11th International Workshop on Java Technologies for Real-time and Embedded System... more Welcome to the 11th International Workshop on Java Technologies for Real-time and Embedded Systems - JTRES 2013. aicas is proud to be able to host the leading forum on using Java technology in real-time and embedded systems. Real-Time Java has gone a long way from being a small niche within the Java community to being an accepted technology in the very demanding real-time and safety critical domain. Today, there are millions of real-time Java applications in the field. New trends such as Internet-to-the-edge bring enormous additional potential for Java in areas that require guarantees on timing, controlled resource usage, and safety guarantees.

A Static Memory Safety Annotation System for Safety Critical Java

Embedded systems must be able to operate for long periods of time with limited memory. Dynamic me... more Embedded systems must be able to operate for long periods of time with limited memory. Dynamic memory allocation is often discouraged in such systems as it requires careful analysis to rule out memory-related software defects. This paper presents an annotation system that can be used to rule out memory access errors in programs written in a subset of the Java programming language which targets safety critical applications. The annotations are optional. When present, they are used by the compiler to report, ahead of time, potential memory access errors. The proposed system is part of the upcoming Safety Critical Java Specification. It has been evaluated on a number of small benchmark programs (26 KLOC of Java code) and implemented in the oSCJ real-time Java virtual machine leading to performance improvements ranging from 1.7% to 26%.

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The real-time behavior of dynamic memory management in C++

rtas, 1995

Dynamic memory management is an important aspect of modern software engineering techniques based ... more

An overview of the SR language and implementation

ACM Transactions on Programming Languages and Systems, 1988

SR is a language for programming distributed systems ranging from operating systems to applicatio... more SR is a language for programming distributed systems ranging from operating systems to application programs. On the basis of our experience with the initial version, the language has evolved considerably. In this paper we describe the current version of SR and give an overview of its implementation. The main language constructs are still resources and operations. Resources encapsulate processes and variables that they share; operations provide the primary mechanism for process interaction. One way in which SR has changed is that both resources and processes are now created dynamically. Another change is that inheritance is supported. A third change is that the mechanisms for operation invocation-call and send-and operation implementation-proc and in-have been extended and integrated. Consequently, all of local and remote procedure call, rendezvous, dynamic process creation, asynchronous message passing, multicast, and semaphores are supported. We have found this flexibility to be very useful for distributed programming. Moreover, by basing SR on a small number of well-integrated concepts, the language has proved easy to learn and use, and it has a reasonably efficient implementation.

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Writing PERC Programs for Embedded Real-Time Applications

Java™ is a new programming language publicly released by Sun Microsystems in May of 1995 with hop... more Java™ is a new programming language publicly released by Sun Microsystems in May of 1995 with hopes of revolutionizing the software industry. The popular press has responded with numerous articles touting the language's advantages over available alternatives. Since many of the applications which Java is intended to serve have embedded real-time characteristics, we have recently undertaken to develop a set of standard extensions to provide Java programmers with the ability to describe real-time requirements in their Java applications. The standard extensions are embodied in PERC™, a recently announced commercial product that brings Java capabilities to the embedded real-time systems arena. This report summarizes the issues that have influenced the design of PERC. Java is an object-oriented programming language with syntax derived from C and C++. However, Java's designers chose not to pursue full compatibility with C and C++ because they preferred to eliminate from these lan...

Sun Microsystems Initially Developed Java as a Tool to Support Internal Kelvin Nilsen

Instead, Java requires all constant identifiers and functions (methods) to be encapsulated within... more Instead, Java requires all constant identifiers and functions (methods) to be encapsulated within class declarations. Java provides standardized support for multiple threads (lightweight tasks) and automatic garbage collection of dynamically allocated memory. Further, Java fully specifies the behavior of every operator on every type, unlike C and C++ which leave many behaviors implementation-dependent. These changes were designed to improve software scalability, reduce software development and maintenance costs, and to achieve full portability of Java software. Anecdotal evidence suggests that many former C and C++ programmers have enthusiastically welcomed these language improvements. One distinguishing characteristic of Java is its execution model. Java programs are first translated into a fully portable standard bytecode representation. The bytecode is then available for execution in any environment that provides support for a Java virtual machine. A Java virtual machine is simpl...

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Use of PERC Pico in the AIDA avionics platform

Proceedings of the 7th International Workshop on Java Technologies for Real-Time and Embedded Systems - JTRES '09, 2009

Abstract In this paper, we present the DIANA experiment on the use of Java in avionics safety cri... more

Scoped Memory Usage Patterns Proposed Modifications to SCJ API

Real-time Java profiles make use of scoped memory regions Explicit scoping requires care from pro... more Real-time Java profiles make use of scoped memory regions Explicit scoping requires care from programmers Deal with temporary objects Pass scope-allocated objects as arguments to methods Returning scope-allocated objects from methods Look into the expressiveness of the SCJ memory model Explore patterns on how to use it Focus on how to pass arguments and return objects between private memories

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Real-Time Java

this document describes Real-Time Java from the perspective of the application programmer. The pr... more this document describes Real-Time Java from the perspective of the application programmer. The programmer's view of Real-Time Java is characterized as the application programmer interface (API). Accompanying presentation of the API are brief discussions of how particular Real-Time Java features are implemented on both traditional and special Real-Time Java virtual machines. These three different views of each language feature are identified throughout this document as detailed below:

Issues in the Design and Implementation of Real-Time Java

ion helps programmers, including real-time programmers, deal with complexity. But real-time devel... more ion helps programmers, including real-time programmers, deal with complexity. But real-time developers must use abstraction with discretion. They must be able to break through layers of abstraction whenever this is necessary in order to understand or exercise control over real-time behavior. A Real-Time Java program consists of an arbitrary number of real-time activities accompanied by an arbitrary number of runnable threads. The runnable threads have no time-constrained behavior. The discussion of real-time activities provided below makes frequent reference to the real-time executive. See "The Real-Time Executive" on page 14. 1. NewMonics Inc. is currently in the process of refining the "Real-Time Java" API and is promoting a standard API under the product name PERC TM , an acronym that stands for Portable Executive for Reliable Control. In a number of cases, the draft API differs slightly from the design suggested in this document. What is Real-Time Java? 10 Is...

Cache Issues in Real-Time Systems

... Software based cache partitioning is another static tech-nique for reducing the contention fo... more

According to Sun, the reason it's so restrictive regarding use of the Java trademark is to assure... more

Download

Achieving high performance and hard real-time determinism with real-time Java

Session details: Real-time garbage collection

Java Technologies for Real-time and Embedded Systems, Sep 26, 2007

Garbage collection of strings and linked data structures in real time

Software - Practice and Experience, Jul 1, 1988

Download

Real-time is no longer a small specialized niche

... kelvin @ cs.iastate.edu ... Over the years, the mainstream and real-time commu-nities have di... more

Unification of Safety-Critical Java

HAL (Le Centre pour la Communication Scientifique Directe), Feb 1, 2012

Download

IEEE Computer Soc. Press, 1996

Session details: Real-time JVM implementation

Proceedings of the 7th International Workshop on Java Technologies for Real-Time and Embedded Systems

Reliable real-time garbage collection of C++

Computing Systems, Sep 20, 1994

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

A Static Memory Safety Annotation System for Safety Critical Java

Download

The real-time behavior of dynamic memory management in C++

rtas, 1995

Dynamic memory management is an important aspect of modern software engineering techniques based ... more

An overview of the SR language and implementation

ACM Transactions on Programming Languages and Systems, 1988

Download

Writing PERC Programs for Embedded Real-Time Applications

Sun Microsystems Initially Developed Java as a Tool to Support Internal Kelvin Nilsen

Download

Use of PERC Pico in the AIDA avionics platform

Proceedings of the 7th International Workshop on Java Technologies for Real-Time and Embedded Systems - JTRES '09, 2009

Abstract In this paper, we present the DIANA experiment on the use of Java in avionics safety cri... more

Scoped Memory Usage Patterns Proposed Modifications to SCJ API

Download

Real-Time Java

Issues in the Design and Implementation of Real-Time Java

Cache Issues in Real-Time Systems

... Software based cache partitioning is another static tech-nique for reducing the contention fo... more

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