Wegner describes coordination as constrained interaction. We take this approach literally and define a coordination model based on interaction constraints and partial, iterative and interactive constraint satisfaction. Our model captures behaviour described in terms of synchronisation and data flow constraints, plus various modes of interaction with the outside world provided byexternal constraint symbols, on-the-fly constraint generation, and coordination variables. Underlying our approach is an engine performing (partial) constraint satisfaction of the sets of constraints. Our model extends previous work on three counts: firstly, a more advanced notion of external interaction is offered; secondly, our approach enables local satisfaction of constraints with appropriate partial solutions, avoiding global synchronisation over the entire constraints set; and, as a consequence, constraint satisfaction can finally occur concurrently, and multiple parts of a set of constraints can be solved and interact with the outside world in an asynchronous manner, unless synchronisation is required by the constraints. This paper describes the underlying logic, which enables a notion of local solution, and relates this logic to the more global approach of our previous work based on classical logic.

This paper presents the concept of pluggable parallelisation that allows scientists to develop “sequential like” codes that can take advantage of multi-core, cluster and grid systems. In this approach parallel applications are developed by plugging parallelisation patterns/idioms into scientific codes (e.g., “sequential like” codes), softening the move from sequential to parallel programming and promoting the separation between domain specific code and parallelisation issues. Pluggable parallelisation combines three characteristics: 1) parallelisation is performed from “outside to inside”, localising parallelisation concerns into well defined modules, reducing changes required to the domain specific code and avoiding invasive parallelisation of base code; 2) control view is separated from data view promoting a stronger separation of concerns which improves reuse of parallelisation concerns across platforms and enables fine-grained refinements; and 3) abstractions can be composed, supporting the development of more complex patterns based on fine-grained features. This paper presents the concept of pluggable parallelisation and shows how some well-known parallelisation strategies can be implemented in this approach. Results show that this is a feasible approach and performance is competitive with traditional parallel programming.

We describe an approach to the analysis of protocols for wireless sensor networks in scenarios with mobile nodes and dynamic link quality. The approach is based on the theorem proving system PVS and can be used for formal specification, automated simulation and verification of the behaviour of the protocol. In order to demonstrate the applicability of the approach, we analyse the reverse path forwarding algorithm, which is the basic technique used for diffusion protocols for wireless sensor networks.