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The move towards Service Grids, where services are composed to meet the requirements of a user community within constraints specified by the resource provider, present many challenges to service provision and description. To support our research activities in the autonomous composition of services to form a Semantic Service Grid we describe the adoption(More)
We identify two forms of workflow expression, temporal, in which relations may imply temporal dependencies, and spatial, in which they do not. Spatial expressions enable the dynamic modification of the workflow; by raising the level of abstraction they provide flexibility. This flexibility is at the cost of information; temporal expressions can guide(More)
Communication libraries have dramatically made progress over the fifteen years, pushed by the success of cluster architectures as the preferred platform for high performance distributed computing. However, many potential optimizations are left unexplored in the process of mapping application communication requests onto low level network commands. The(More)
In this paper, we present two new methods to simulate Petri Nets: a data parallel simulation and a distributed simulation. Both simulations use an equational representation of the net in the so called (min, +) algebra. The data parallel simulation is based on the use of matrix representation of these equations, and the distributed simulation on the(More)
Communication libraries have dramatically made progress over the fifteen years, pushed by the success of cluster architectures as the preferred platform for high performance distributed computing. However, many potential optimizations are left unexplored in the process of mapping application communication requests onto low level network commands. The(More)
—The increasing numbers of cores, shared caches and memory nodes within machines introduces a complex hardware topology. High-performance computing applications now have to carefully adapt their placement and behavior according to the underlying hierarchy of hardware resources and their software affinities. We introduce the Hardware Locality (hwloc)(More)
Effective exploitation of computational grids can only be achieved when applications are fully integrated with the grid middleware and the underlying computational resources. Fundamental to this exploitation is information. Information about the structure and behaviour of the application, the capability of the computational and networking resources, and the(More)