Abstract
The chapter deals with run-time automatic reconfigurations of distributed embedded control systems following component-based approaches. We classify reconfiguration scenarios into four forms: (1) additions-removals of components, (2) modifications of their compositions, (3) modifications of implementations, and finally (4) simple modifications of data. We define a new multi-agent architecture for reconfigurable systems where a Reconfiguration Agent which is modelled by nested state machines is affected to each device of the execution environment to apply local reconfigurations, and a Coordination Agent is proposed for any coordination between devices in order to guarantee safe and coherent distributed reconfigurations. We propose technical solutions to implement the whole agent-based architecture, by defining UML meta-models for agents. In the execution scheme, a task is assumed to be a set of components having some properties independently from any real-time operating system. To guarantee safety reconfigurations of tasks at run-time, we define service and reconfiguration processes for tasks and use the semaphore concept to ensure safety mutual exclusions. We apply the priority ceiling protocol as a method to ensure the scheduling between periodic tasks with precedence and mutual exclusion constraints.