Section: Overall Objectives

Overall Objectives

With digital equipment becoming increasingly networked, either on wired or wireless networks, for personal and professional use alike, distributed software systems have become a crucial element in information and communication technologies. The study of these systems forms the core of the ARLES project-team's work, which is specifically concerned with defining new system software architectures, based on the use of emerging networking technologies.

Since the 90s, middleware has emerged as a prominent solution to overcome the heterogeneity of distributed infrastructure. It establishes a software layer that homogenizes infrastructure diversities by means of a well-defined and structured distributed programming model. Moreover, middleware provides building blocks to be exploited by applications for enforcing non-functional properties, such as dependability and performance. Finally, by providing reusable solutions for the development of distributed systems, which is increasingly demanding, the role of middleware has proved central in the software system development practice.

However, the development of middleware itself remains a complex task (V. Issarny et al. Systematic Aid for Developing Middleware Architectures. In Communications of the ACM, Special Issue on Adaptive Middleware, 45(6). 2002.). In particular, middleware must provide the adequate networking and computing abstractions to match the distributed application requirements. Further, while the development of legacy middleware has been significantly driven by requirements of distributed information systems, the ongoing evolution of the networking environment leads to a much broader application of distributed computing — including, among others, the proliferation of disparate mobile computing devices and smart phones, and the inclusion of wireless sensor networks into modern and future pervasive systems. As a result of the above, new requirements arise for middleware, e.g., supporting open and mobile networking, as well as context awareness [5] . Among these new requirements, we are especially interested in applications involving social interactions between the users of modern smart phones, which involve addressing issues of trust and privacy along with efficiency of algorithms to deal with the lack of resources.

In the above context, ARLES studies the engineering of middleware-based systems, with a special emphasis on enabling interoperability in the ubiquitous computing (M. Weiser. The Computer for the Twenty-First Century. In Scientific American. 1991.) and subsequent pervasive computing (M. Satyanarayanan. Pervasive Computing: Vision and Challenges. In IEEE Personal Communications. August 2001.) and ambient intelligence (E. Aarts et al. Ambient Intelligence. In The Invisible Future: the Seamless Integration of Technology into Everyday Life. McGraw-Hill. 2002.) visions, keeping in view the advances in the constitution of these systems, both in terms of the various communication and discovery protocols used, as well as the hardware and software platforms available. Our research is more specifically focused on eliciting middleware for pervasive computing, from foundations and architectural design to prototype implementations. Proposed middleware and programming abstractions shall then effectively leverage networked resources, in particular accounting for advanced wireless networking technologies, while also addressing concerns raised due to the presence of large numbers of extremely low-power devices such as wireless sensors and actuators. This raises a number of complementary research challenges:

• System architecture: How to architect and further program pervasive computing systems out of the resources available in the highly dynamic networking environment?

• System modeling: How to abstract and further model the networked resources and related networking environment for distributed pervasive computing?

• Interoperability: How to actually overcome the heterogeneity of the pervasive computing environment, including middleware heterogeneity?

• Networking: How to benefit from the rich wireless networking technologies?

• Quality of service: How to effectively master the high dynamics and openness of pervasive computing environments and, in particular, how to ensure dependability and performance in such environments?

All the above mentioned challenges are inter-related, calling for their study in both the software engineering and distributed systems domains. Indeed, proposed middleware abstractions and related programming models shall effectively foster the development of robust distributed software systems, which, at the same time, must be implemented in an efficient way. Specifically:

• In the software engineering domain, ARLES studies resource abstractions and interaction paradigms to be offered by middleware, together with the associated languages, methods and tools for describing and composing the abstracted resources into applications. Our primary goal is to foster the development of robust and interoperable distributed systems that are highly dynamic to adapt to the ever-changing networking environment, and further meet quality of service requirements.

• In the distributed systems domain, ARLES studies innovative middleware architectures and related distributed algorithms and protocols for the efficient networking of distributed resources into distributed pervasive systems, in particular taking into account the high mobility and heterogeneity of the constituent nodes.