Section: New Results
Virtual computing environments
Virtual Collaborative Platforms
Participant : Toan Nguyen.
Based on the previous work on Virtual Computing Environments with CNES (2004-2006), the OPALE project/team is working on Virtual Collaborative Platforms which are specifically adapted to Multiphysics Collaborative projects. This is in particular studied in the framework of the European AEROCHINA2 support action. The approach considers not only code coupling for multiphysics applications in aeronautics, but includes also interactions between participant teams, knowledge sharing through numerical databases and communication tools using Wikies. The design of a proof of concept demonstrator is planned in the AEROCHINA2 project, started in October 2007. Indeed, large scale multiphysics problems are expected to be orders of magnitude larger than existing single discipline applications, like weather forcast which involve ocean and atmosphere circulation, environmental disaster prevention and emergency management. Their complexity requires new computing technologies for the management of multi-scale and multi-physics problems, large amounts of data and heterogenous codes. Among these technologies are wide area networks and distributed computing, using cluster and grid-based environments. It is clear that supercomputers, PC-clusters and, to a limited extent wide area grids, are currently used for demanding e-science applications, e.g., nuclear and flight dynamics simulation. It is not so clear however what approaches are currently the best for developing multiphysics applications. We advocate the use of an appropriate software layer called upperware, which, combined with cluster and grid-based techniques, can support virtualization of multidiscipline applications when running multidisciplinary codes and business software, e.g., decision support tools. This paves the way for "Virtual Collaborative Platforms". Unlike Wikis and other collaborative tools widely accepted for document editing, virtual collaborative platforms are used to deploy distributed and parallel multiphysics simulation tools. Their execution may be controlled and monitored by distributed workflow systems that may be hierarchically composed. Work in progress is done on this subject, particularly on workflow management system with fault-tolerance, interaction and exception handling mechanisms, in partnership with other participants to European projects, e.g., AEROCHINA.
Workflow systems for multidiscipline optimization
Participants : Jean-Antoine Désidéri, Toan Nguyen, Laurentiu Trefan.
Workflows systems are the focus of many e-Science applications, ranging from astrophysics to bioinformatics. Among the most popular workflow management systems are Taverna, Kepler, Pegasus, Bonita, YAWL and many others. They complement scientific software programming environments like Dakota, Scilab and Matlab in their ability to provide complex application factories that can be shared, reused and evolved. Further, they support the incremental composition of complex hierarchic composite applications. Providing a control flow approach, they also complement the usual dataflow approach used in programming toolboxes. Another bonus is that they provide seamless user interfaces, masking technicalities of distributed, programming and administrative layers, thus allowing the users and experts to concentrate on their areas of interest.
The OPALE project is investigating the use of the YAWL system for distributed and parallel multidiscipline optimization. The goal is to develop a resilient workflow system for large-scale optimization applications. It is based on extensions to the YAWL system to add resilience and remote computing features on high-performance distributed infrastructures [45] [33] [34] . This includes large-PC clusters connected to broadband networks. It also includes interfaces with the Scilab scientific computing toolbox and the ProActive middleware. A prototype implementation is underway for the OMD2 project ("Optimisation Mutlidiscipline Distribuée") of the French Agence Nationale de la Recherche (ANR). A doctoral program has been launched on this topic.
