A shared distributed infrastructure is formed by federating computation resources from multiple domains. Such a shared infrastructure provides aggregated computation resources to a large number of users. Meanwhile, virtualization technologies, at machine and network levels, are maturing and enabling mutually isolated virtual computation environments for executing arbitrary parallel/distributed applications on top of such a shared physical infrastructure. In this paper, we take one step further by supporting autonomic adaptation of virtual computation environments as active. integrated entities. More specifically, driven by both dynamic availability of infrastructure resources and dynamic application resource demand, a virtual computation environment is able to automatically re-locate itself across the infrastructure an
