Transparent Risk-free Synchronization in the High-Level-Architecture Interoperability Standard

The high-level-architecture (HLA) is an IEEE standard for the interoperability and integration of (autonomous) simulation packages and applications (termed federates in the HLA context). It is based on a middleware-level component referred to as run-time-infrastructure (RTI) offering a set of interoperability services to the overlying simulation software. Time-management is the suite of services allowing synchronized execution among the federates, which, according to the HLA specification, covers pure conservative and pure optimistic synchronization schemes. In this paper we provide the design and implementation of a software layer, we refer to as risk-free-speculator (RFS), which supports an optimistic oriented intermediate approach to synchronization embedding the aggressiveness property of optimistic systems, but discarding risk. This is done in a totally transparent manner to the overlying applications, and does not even require any modification of the underlying RTI. The effectiveness of RFS has been tested against simulated demonstration exercises using the Joint Semi-Automated Forces (JSAF) simulation program.