The OSGi framework is a Java-based, centralized, component oriented platform. It is being widely adopted as an execution environment for the development of extensible applications. However, current Java Virtual Machines are unable to isolate components from each other. For instance, a malicious component can freeze the complete platform by allocating too much memory or alter the behavior of other components by modifying shared variables. This paper presents I-JVM, a Java Virtual Machine that provides a lightweight approach to isolation while preserving compatibility with legacy OSGi applications. Our evaluation of I-JVM shows that it solves the 8 known OSGi vulnerabilities that are due to the Java Virtual Machine and that the overhead of I-JVM compared to the JVM on which it is based is below 20%.

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Dynamic flexibility is a major challenge in modern system design to react to context or applicative requirements evolutions. Adapting behaviors may impose substantial code modification across the whole system, in the field, without service interruption and without state loss. This paper presents the JnJVM, a full Java virtual machine (JVM) that satisfies these needs by using dynamic aspect weaving techniques and a component architecture. It supports adding or replacing its own code, while it is running, with no overhead on unmodified code execution. Our measurements reveal similar performance when compared with the monolithic JVM Kaffe. Three illustrative examples show different extension scenarios: (i) modifying the JVMs behavior; (ii) adding capabilities to the JVM; and (iii) modifying applications behavior. Copyright © 2008 John Wiley & Sons, Ltd.

International audienceCode offloading is a promising effort for embedded systems and load-balancing. Embedded systems will be able to offload computation to nearby computers and large-scale applications will be able to load-balance computation during high load. This paper presents a runtime infrastructure that transparently distributes computation between interconnected workstations. Application source code is not modified: instead, dynamic aspect weaving within an extended virtual machine allows to monitor and distribute entities dynamically. Runtime policies for distribution can be dynamically adapted depending on the environment. A first evaluation of the system shows that our technique increases the transaction rate of a Web server during high load by 73%