Abstract not found

Since progress in many avenues of science depends heavily on simulated results, discrete event simulators have been the subject of much research into their efficient design and execution. This paper introduces JiST, a Java-based simulation framework that executes discrete event simulations both efficiently and transparently. Our system differs from existing work in that it embeds simulation time semantics into the Java execution model, but does so without inventing a new language, without requiring a specialized compiler and without utilizing a custom runtime. The result is a flexible simulation environment that allows sequential simulation execution and also transparently supports both parallel and optimistic execution with automatic checkpointing and rollback. The JiST approach uses a convenient single system image abstraction across a cluster of nodes, that allows for dynamic network and computational load-balancing and fine-grained migration of simulation state. The system provides standard benefits that the modern Java runtime affords, such as type-safety, garbage collection and portability. Nevertheless, JiST performs well, either matching or exceeding the performance of ns2 and the highly optimized GloMo-Sim runtime in both throughput and memory consumption. We illustrate the practicality of the JiST framework by applying it to the construction of SWANS, a scalable wireless ad hoc network simulator.

Extension languages are an important part of modern applications development. Java as a platform does not provide a standard extension language. Scheme is one possible choice as an extension language for Java. There are a variety of techniques for implementing Scheme in Java varying from interpreting s-expressions to compiling into Java byte-codes. The historical evolution of one implementation is discussed over the course of several years. The design of the Java-to-Scheme and Scheme-to-Java interfaces is reviewed. The advantages and disadvantages of Java and Scheme are compared.

Abstract This paper presents Genesys, a framework for the high-level construction of property conform code generators. Genesys is an integral part of jABC, a flexible framework designed to enable a systematic model-driven development of systems and applications on the basis of an (extensible) library of well-defined, reusable building blocks. Within jABC, Genesys manages the construction of code generators for jABC’s models. So far, Genesys has been used to develop code generators for a variety of different target platforms, like a number of Java-based platforms, mobile devices, BPEL engines, etc. Since the code generators are themselves built within the jABC in a model-driven way, concepts like bootstrapping and reuse of existing components enable a fast evolution of Genesys ’ code generation library, and a high degree of self-application. Due to its increasing complexity and its high degree of reuse, Genesys profits from model checking-based verification. This way, jABC’s models of code generators can be automatically checked wrt. wellformedness properties, to ensure that the models do indeed only consist of building blocks which are suitable for the considered target platforms, and whose versions are mutually compatible. It can be also be verified that the code generation process only starts after a successful initialization phase, and that the generated code is always packaged with all the required libraries. We will illustrate the ease of extension and flexibility of the Genesys framework by describing the