Federate Migration in a Service Oriented HLA RTI

The High Level Architecture provides a general framework for distributed simulation, promoting reusability and interoperability of simulation components (federates). Large scale distributed simulation, in which federates run on many heterogenous computing machines may benefit from migrating federates among these machines for load- balancing and fault-tolerance. However, the HLA framework does not provide formal support for federate migration currently. We have previously developed a Service Oriented HLA RTL (SOHR) framework, which provides HLA RTL functionalities via the cooperation of a set of Grid services. SOHR is developed with migration support features by using a decoupled federate design. In this paper, a basic federate migration protocol is first proposed to illustrate the process of federate migration in SOHR. Then two optimized protocols are further developed to overlap federate migration with federate execution for the purpose of reducing migration overhead. Experiments show that the migration overhead is reduced considerably in the optimized protocols.