There is a growing interest in the area of self-healing systems. Self-healing does however impose considerable demands on system infrastructures—especially in terms of openness and support for reconfigurability. This paper proposes that the selfawareness inherent in reflective technologies lends itself well to the construction of self-healing systems. In particular, the paper examines the support provided by the Open ORB reflective middleware technology for the construction of this increasingly important class of system.

We argue that pervasive computing offers not only tremendous opportunities and exciting research challenges but also possible negative environmental impacts, particularly in terms of physical waste and energy consumption. These environmental impacts will come under increasing government and consumer scrutiny, and like other disciplines (e.g. architecture, transportation), pervasive computing will have to adapt accordingly. Further, we argue that software–related issues will play an increasing role in reducing the environmental impact of computing. We thus propose that an important challenge for pervasive computing is to develop research in new architectures, design methodologies, metrics, algorithms and operating systems to minimize these impacts. We then discuss specific research issues and questions that arise in three phases of the device lifecycle: minimizing resource usage for manufacture and operation, maximizing device lifetime, and improving recyclability. Categories and Subject Descriptors C.2.0 [Computer-communication networks]: Network architecture and design – wireless communication, distributed

Abstract. To deal with the increasing complexity of software systems and uncertainty of their environments, software engineers have turned to self-adaptivity. Self-adaptive systems are capable of dealing with a continuously changing environment and emerging requirements that may be unknown at design-time. However, building such systems cost-effectively and in a predictable manner is a major engineering challenge. In this paper, we explore the state-of-the-art in engineering self-adaptive systems and identify potential improvements in the design process. Our most important finding is that in designing self-adaptive systems, the feedback loops that control self-adaptation must become first-class entities. We explore feedback loops from the perspective of control engineering and within existing self-adaptive systems in nature and biology. Finally, we identify the critical challenges our community must address to enable systematic and well-organized engineering of self-adaptive and self-managing software systems. 1

A common approach to adding self-management capabilities to a system is to provide one or more external control modules, whose responsibility is to monitor system behavior, and adapt the system at run time to achieve various goals (configure the system, improve performance, recover from faults, etc.). An important problem arises when there is more than one such self-management module: how can one make sure that they are composed to provide consistent and complementary benefits? In this paper we describe a solution that introduces a self-management coordination architecture and infrastructure to support such composition. We focus on the problem of coordinating self-configuring and self-healing capabilities, particularly with respect to global configuration and incremental repair. We illustrate the approach in the context of a self-managing video teleconference system that composes two pre-existing adaptation modules to achieve synergistic benefits of both. 1

This paper evaluates the use of AspectJ, a general-purpose aspectoriented extension to Java, to provide adaptive behavior for J2ME applications in a modularized way. Our evaluation is based on the development of a simple but non-trivial dictionary application where new adaptive behavior was incrementally implemented using AspectJ. Our main contribution is to show that the AspectJ language can be used to implement several adaptive concerns, which allow the application to have different behaviors according to changes in its environment.

Abstract: In distributed and mobile environments, the connections among the hosts on which a software system is running are often unstable. As a result of connectivity losses, the overall availability of the system decreases. The distribution of software components onto hardware nodes (i.e., deployment architecture) may be ill-suited for the given target hardware environment and may need to be altered to improve the software system’s availability. The critical difficulty in achieving this task lies in the fact that determining a software system’s deployment that will maximize its availability is an exponentially complex problem. In this paper, we present an automated, flexible, software architecturebased solution for disconnected operation that increases the availability of the system during disconnection. We provide a fast approximative solution for the

Dynamic architectural change is defined as the addition and removal of components and connectors. Dynamic software architectures are those architectures that modify their architecture and enact the modifications during the system’s execution. This behavior is most commonly known as run-time evolution or dynamism. As dynamic software architecture use becomes more widespread, it is important to gain a better understanding of this type of software evolutionary change and be able to classify formalisms, approaches and tools. Current evaluations in the areas of software architecture and evolutionary change have made strides in classification but are not sufficient to evaluate dynamic software architectures. A dedicated comparison of dynamic software architectures and architectural formalisms is necessary in order to gain a deeper understanding of run-time evolution. In this paper we present a set of classification criteria for the comparison of dynamic software architectures based on: change type, change process, and change infrastructure. We demonstrate the use of the criteria by classifying three types of dynamic software architectural change. In addition we survey 14 current approaches to the formal specification of dynamic software architectures based on graphs, process algebras, logic, and other formalisms. We then

Abstract Context-aware applications monitor changes in their operating environment and switch their behaviour to keep satisfying their requirements. Therefore, they must be equipped with the capability to detect variations in their operating context and to switch behaviour in response to such variations. However, specifying monitoring and switching in such applications can be difficult due to their dependence on varying contextual properties which need to be made explicit. In this paper, we present a problemoriented approach to represent and reason about contextual variability and assess its impact on requirements; to elicit and specify concerns facing monitors and switchers, such as initialisation and interference; and to specify monitoring and switching behaviours that can detect changes and adapt in response. We illustrate our approach by applying it to a published case study.

Current database management system technology is not well equipped to provide adequate support for what has been deemed the 3 d wave of computing -- Ubiquitous Computing. Such applications require systems that are sufficiently lightweight and customisable to provide high performance while consuming minimal power, yet extensible enough to adapt to a constantly changing environment. Current DBMS architectures inherently do not provide this level of customisation or adaptability. Therefore we suggest an alternative where database systems shake off their relatively static monolithic structure and become open sets of fine-grained components providing a collection of key information provision services and moreover have the ability to adapt. This paper explores the motivation for componentisation and how modem operating systems research can influence the DBMS architecture. If components are the answer, then are we announcing the end of database management systems as we currently know them, or are we just describing a database machine for the 21 st century? 1

Abstract. Current peer-to-peer architectures are hardly resistant against unanticipated exceptions such as the failure of single peers. This can be justified by the absence of sophisticated models for exception detection and resolution in peer-to-peer architectures. On the other hand, existing generic models for such self-adaptable architectures are rather theoretical and less suitable for the usage by end-users. In this work, strategies for a new self-adaptability model in peerto-peer architecture are presented incorporating the component technology as the conceptual foundation. The claim of this approach is that through the intuitive nature of the component technology the process of self-adaptability becomes more applicable and more comprehendible even for less experienced end-users. 1