Java Dust: How Small Can Embedded Java Be?

Java is slowly being accepted as a language and platform for embedded devices. However, the memory requirements of the Java library and runtime are still troublesome. A Java system is considered small when it requires less than 1 MB, and within the embedded domain small microcontollers with a few KB on-chip Flash memory and even less on-chip RAM are very common. For such small devices Java is a clearly challenging. In this paper we present the combination of the Java compiler Muvium for microcontrollers with the tiny soft-core Leros for an FPGA. To the best of our knowledge, the presented embedded Java system is the smallest Java system available. The Leros processor consumes less than 5 % of the logic cells of the smallest FPGA from Altera and the Muvium compiler produces a JVM, including the Java application, that can execute in a few KB ROM and less than 1 KB RAM. The Leros processor is available in open-source and the Leros port of Muvium is freely available

Run-time compilation techniques for wireless sensor networks

Wireless sensor networks research in the past decade has seen substantial initiative,support and potential. The true adoption and deployment of such technology is highly dependent on the workforce available to implement such solutions. However, embedded systems programming for severely resource constrained devices, such as those used in typical wireless sensor networks (with tens of kilobytes of program space and around ten kilobytes of memory), is a daunting task which is usually left for experienced embedded developers.Recent initiative to support higher level programming abstractions for wireless sensor networks by utilizing a Java programming paradigm for resource constrained devices demonstrates the development benefits achieved. However, results have shown that an interpreter approach greatly suffers from execution overheads. Run-time compilation techniques are often used in traditional computing to make up for such execution overheads. However, the general consensus in the field is that run-time compilation techniques are either impractical, impossible, complex, or resource hungry for such resource limited devices.In this thesis, I propose techniques to enable run-time compilation for such severely resource constrained devices. More so, I show not only that run-time compilation is in fact both practical and possible by using simple techniques which do not require any more resources than that of interpreters, but also that run-time compilation substantially increases execution efficiency when compared to an interpreter

A Low-Footprint Java-to-Native Compilation Scheme Using Formal Methods

Ahead-of-Time and Just-in-Time compilation are common ways to improve runtime performances of restrained systems like Java Card by turning critical Java methods into native code. However, native code is much bigger than Java bytecode, which severely limits or even forbids these practices for devices with memory constraints. In this paper, we describe and evaluate a method for reducing natively-compiled code by suppressing runtime exception check sites, which are emitted when compiling bytecodes that may potentially throw runtime exceptions. This is made possible by completing the Java program with JML annotations, and using a theorem prover in order to formally prove that the compiled methods never throw runtime exceptions. Runtime exception check sites can then safely be removed from the generated native code, as it is proved they will never be entered. We have experimented our approach on several card-range and embedded Java applications, and were able to remove almost all the exception check sites. Results show memory footprints for native code that are up to 70% smaller than the non-optimized version, and sometimes as low than 115% the size of the Java bytecode when compiled for ARM thumb

A Low-Footprint Java-to-Native Compilation Scheme Using Formal Methods

Ahead-of-Time and Just-in-Time compilation are common ways to improve runtime performances of restrained systems like Java Card by turning critical Java methods into native code. However, native code is much bigger than Java bytecode, which severely limits or even forbids these practices for devices with memory constraints. In this paper, we describe and evaluate a method for reducing natively-compiled code by suppressing runtime exception check sites, which are emitted when compiling bytecodes that may potentially throw runtime exceptions. This is made possible by completing the Java program with JML annotations, and using a theorem prover in order to formally prove that the compiled methods never throw runtime exceptions. Runtime exception check sites can then safely be removed from the generated native code, as it is proved they will never be entered. We have experimented our approach on several card-range and embedded Java applications, and were able to remove almost all the exception check sites. Results show memory footprints for native code that are up to 70% smaller than the non-optimized version, and sometimes as low than 115% the size of the Java bytecode when compiled for ARM thumb