PARADIS: an Adaptive Middleware for Dynamic Task Allocation in a Grid

The major purpose of a Grid is to federate multiple powerful r e- sources into a single virtual entity which can be accessed tr ansparently and efficiently by external users. As a Grid is usually an unrelia ble system involving heterogeneous resources located in different geographica l domains, distributed and fault-tolerant resource allocation services have to beprovided. In particular when a crash occurs tasks have to be reallocated quickly and a utomatically, in a completely transparent way from the users' point of view. T his paper presents PARADIS, an adaptive middleware based on a set of basic agreement ser vices that has been integrated within an experimental Grid dedica ted to genomic ap- plications. Most of these time-consuming applications arecomposed of a huge number of independent tasks.