Adaptive and reconfigurable systems can respond to environmental changes including hardware/software defects and variability, resource changes, and non-continual feature usage, as well as provide support to maintenance at run time, extensibility and evolving requirements. As such, these systems have the potential to exhibit an extended operations space and lifetime and improve efficiency in the use of system resources.

However, such flexibility also incurs overhead in terms of system complexity and resource requirements. For example, an adaptive system requires means for reconfiguration that allows it to adapt to changes. These means and their mechanisms introduce additional complexity to the design and the architecture, and they also require additional resources such as computation, power, and, for distributed reconfiguration, communication bandwidth.

Moreover, to take advantage of adaptability, new specification methods are needed, to define acceptable adaptation ranges which will be explored by the system at run-time to improve a given performance metric. However, current operating systems and network protocols are not designed to support such flexible requirements, and generally do not support complementary reflexive mechanisms that are needed to allow the application to adjust itself to the current configuration.

Finally, programming such systems also needs adequate middleware layers that provide adequate abstractions and interfaces for the development of adaptive applications. Building such middleware so that it preserves adaptability while providing performance guarantees together with satisfying other usual goals, such as modularity, reusability and scalability, is a challenge still to be conquered.

This special issue contains the papers from the 2nd International Workshop on Adaptive and Reconfigurable Embedded Systems (APRES'09) held in connection with the Embedded Systems Week 2009 in Grenoble, France, after the inaugural edition in St Louis, USA, within the 1st Cyber-Physical Week. The workshop aimed at discussing new and on-going research in the development and use of adaptive and reconfigurable embedded systems and gathering feedback from the embedded systems community at large. Of particular interest were new concepts and ideas for modeling and analyzing tradeoffs of embedded and real-time systems, novel algorithms and mechanisms to realize adaptation and reconfigurability, and experience reports with practical or industrial case studies. Among the 17 initial submissions, 12 papers were selected and organized in 3 sessions, covering a wide spectrum of the subject of Adaptive and Reconfigurable Embedded Systems. The workshop was funded by the European ArtistDesign Network of Excellence on Embedded Systems Design and to the Ontario Ministry of Research and Innovation (Canada).

Special Issue Editors:
Luís Almeida, University of Aveiro, Portugal
Karl-Erik Årzén, Lund University, Sweden
Sebastian Fischmeister, University of Waterloo, Canada
Insup Lee, University of Pennsylvania, USA
Julián Proenza, Univ. of the Balearic Islands, Spain