The technologies, architectures, and methodologies traditionally used to develop distributed applications exhibit a variety of limitations and drawbacks when applied to large scale distributed settings (e.g., the Internet). In particular, they fail in providing the desired degree of configurability, scalability, and customizability. To address these issues, researchers are investigating a variety of innovative approaches. The most promising and intriguing ones are those based on the ability of moving code across the nodes of a network, exploiting the notion of mobile code. As an emerging research field, code mobility is generating a growing body of scientific literature and industrial developments. Nevertheless, the field is still characterized by the lack of a sound and comprehensive body of concepts and terms. As a consequence, it is rather difficult to understand, assess, and compare the existing approaches. In turn, this limits our ability to fully exploit them in practice, and to further promote the research work on mobile code. Indeed, a significant symptom of this situation is the lack of a commonly accepted and sound definition of the term "mobile code" itself. This paper presents a conceptual framework for understanding code mobility. The framework is centered around a classification that introduces three dimensions: technologies, design paradigms, and applications. The contribution of the paper is twofold. First, it provides a set of terms and concepts to understand and compare the approaches based on the notion of mobile code. Second, it introduces criteria and guidelines that support the developer in the identification of the classes of applications that can leverage off of mobile code, in the design of these applications, and, finally, in the selection of the most appropriate implementation technologies. The presentation of the classification is intertwined with a review of the state of the art in the field. Finally, the use of the classification is exemplified in a case study.

This paper discusses the challenges in computer systems research posed by the emerging field of pervasive computing. It first examines the relationship of this new field to its predecessors: distributed systems and mobile computing. It then identifies four new research thrusts: effective use of smart spaces, invisibility, localized scalability, and masking uneven conditioning. Next, it sketches a couple of hypothetical pervasive computing scenarios, and uses them to identify key capabilities missing from today's systems. The paper closes with a discussion of the research necessary to develop these capabilities.

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ion and delegation: Agents can be made extensible and composable in ways that common iconic interface objects cannot. Because we can "communicate" with them, they can share our goals, rather than simply process our commands. They can show us how to do things and tell us what went wrong (Miller and Neches 1987). . Flexibility and opportunism: Because they can be instructed at the level of 16 BRADSHAW goals and strategies, agents can find ways to "work around" unforeseen problems and exploit new opportunities as they help solve problems. . Task orientation: Agents can be designed to take the context of the person's tasks and situation into account as they present information and take action. . Adaptivity: Agents can use learning algorithms to continually improve their behavior by noticing recurrent patterns of actions and events. Toward Agent-Enabled System Architectures In the future, assistant agents at the user interface and resource-managing agents behind the scenes will increas...

of these models for interaction between Grid components to decide resource service value, and the necessary infrastructure to realize each model. In addition to usual services offered by Grid computing systems, we need an infrastructure to support interaction protocols, allocation mechanisms, currency, secure

First of all, I would like to express my deepest sense of gratitude to my supervisor, Prof. Nazim AGOULMINE, for his guidance, encouragement and excellent advice throughout my research work. I am thankful to the members of my thesis committee, Mikael SALAUN, Josef NOLL, Hossam AFIFI, Sasitharan BALASUBRAMANIAM, Romain DURAND for the time and effort that they invested in judging the contents of my thesis. I am pleased to thank all my colleagues at Networks and Multimedia Systems Research Group (LRSM) for their support and their comradeship; especially to Mehdi Nafa, Elyes Lehtihet, Yacine Ghamri Doudane and Quoc Thinh Nguyen, who worked closely with me in Polymage, SEIMONET and SUMO projects. Finally, I take this opportunity to express my profound gratitude to my beloved parents and sister for their invaluable love and support throughout the years. I cannot thank you enough for your unwavering support, encouragement, and for always believing in me. Lastly, I would like to thank my fiancé, for her love, encouragement and patience. iii

the Nordic’s µBlue (“MicroBlue”) nRF8001 connectivity-on-chip solution. This follows the Bluetooth SIG’s official adoption of Bluetooth low energy in December 2009

The diffusion of wireless terminals with multiple communication interfaces, e.g., IEEE 802.11, Bluetooth, and UMTS on the same device, is pushing towards the necessity of middleware solutions to dynamically and seamlessly select the proper connectivity technology to exploit at any time

, weight, etc.). Based on this scenario, we have designed and implemented a seamless application framework called the Roam system that can both assist developers to build multi-platform applications that can run on heterogeneous devices and allow a user to move/migrate a running application among

This thesis provides a way for users to easily add and remove devices to secure groups, allowing for a more intuitive way of making connections between devices. These groups allow users to seamlessly make connections between their devices once devices are added to a group. Current models