Chaker Nakhli

Bio: Chaker Nakhli is an academic researcher. The author has contributed to research in topics: Machine code & Real time Java. The author has an hindex of 2, co-authored 2 publications receiving 32 citations.

A Methodology and Tool Support for Generating Scheduled Native Code for Real-Time Java Applications

Abstract: Current trends in industry are leading towards the use of Java [5] as a programming language for implementing embedded and real-time applications. From the software engineering perspective, the Java environment is indeed a very attractive development framework. Object-oriented programming provides encapsulation of abstractions into objects that communicate through clearly defined interfaces. Dynamic loading eases the maintenance and improvement of complex applications with evolving requirements and functionality. Besides, Java provides built-in support for multi-threading.

Efficient Region-Based Memory Management for Resource-limited Real-Time Embedded Systems.

Abstract: This paper presents a simple and efficient static analysis algorithm, combined with a region allocation policy for real-time embedded Java applications. The goal of this work is to provide a static analysis mechanism efficient enough to be integrated in an assisted-development environment, and to implement region-based memory management primitives suited for resource-limited platforms such as smart cards.

Composition for component-based modeling

Abstract: We propose a framework for component-based modeling using an abstract layered model for components. A component is the superposition of two models: a behavior model and an interaction model. Interaction models describe architectural constraints induced by connectors between components.We propose and analyze general requirements for component composition that motivated and guided the development of the framework. We define an associative and commutative composition operator on components encompassing heterogeneous interaction. As a particular instance of the proposed framework, we consider components where behavior models are transition systems and interaction models are described by priority relations on interactions. This leads to a concept of "flexible" composition different from usual composition in that it preserves deadlock-freedom and is appropriate for correctness by construction. Nevertheless, flexible composition is a partial operation. Product systems should be interaction safe in the sense that they do not violate constraints of the interaction model.We propose results ensuring correctness by construction of a system from properties of its interaction model and of its components. The properties considered include global deadlock-freedom, individual deadlock-freedom of components, and interaction safety.

A Static Analysis for Synthesizing Parametric Specifications of Dynamic Memory Consumption.

Abstract: We present a static analysis for computing a parametric upper-bound of the amount of memory dynamically allocated by (Java-like) imperative object-oriented programs. We propose a general procedure for synthesizing non-linear formulas which conservatively estimate the quantity of memory explicitly allocated by a method as a function of its parameters. We have implemented the procedure and evaluated it on several benchmarks. Experimental results produced exact estimations for most test cases, and quite precise approximations for many of the others. We also apply our technique to compute usage in the context of scoped memory and discuss some open issues.

Code aware resource management

Abstract: Multithreaded programs coordinate their interaction through synchronization primitives like mutexes and semaphores, which are managed by an OS-provided resource manager. We propose algorithms for the automatic construction of code-aware resource managers for multithreaded embedded applications. Such managers use knowledge about the structure and resource usage (mutex and semaphore usage) of the threads to guarantee deadlock freedom and progress while managing resources in an efficient way. Our algorithms compute managers as winning strategies in certain infinite games, and produce a compact code description of these strategies. We have implemented the algorithms in the tool Cynthesis. Given a multithreaded program in C, the tool produces C~code implementing a code-aware resource manager. We show in experiments that Cynthesis produces compact resource managers within a few minutes on a set of embedded benchmarks with up to 6 threads.

Scoped types and aspects for real-time Java memory management

Abstract: 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.