This article introduces model checking as an alternative method to estimate the latency and parallelism of asynchronous Realtime Interactive Systems (RISs). Five typical concurrency and synchronization schemes often found in concurrent Virtual Reality (VR) and computer game systems are identified as use-cases. These use-cases guide the development a) of software primitives necessary for the use-case implementation based on asynchronous RIS architectures and b) of a graphical editor for the specification of various concurrency and synchronization schemes (including the use-cases) based on these primitives. Several model-checking tools are evaluated against typical requirements in the RIS area. As a result, the formal model checking language Rebeca and its model checker RMC are applied to the specification of the use-cases to estimate latency and parallelism for each case. The estimations are compared to measured results achieved by classical profiling from a real-world application. The estimated results of the latencies by model checking approximated the measured results adequately with a minimal difference of 3.9% in the best case and -26.8% in the worst case. It also detected a problematic execution path not covered by the stochastic nature of the measured profiling samples. The estimated results of the degree of parallelization by model checking are approximated with an minimal difference of 9.3% and a maximal difference of -28.8%. Finally, the effort of model checking is compared to the effort of implementing and profiling a RIS.

This article describes a set of metrics for a message-passing-based asynchronous Realtime Interactive System (RIS). Current trends in concurrent RISs are analyzed, several profiling tools are outlined, and common metrics are identified. A set of nine metrics is presented in a unified and formalized way. The implementation of a profiler that measures and calculates these metrics is illustrated. The implementation of an instrumentation and a visualization tool are described. A case study shows how this approach proved beneficial during the optimization of latency of an actual system.

We present SiXton 's Curse-a computer game-to illustrate the ben efits of a novel simulation platform. Simulator X [2] targets vir tual, augmented, and mixed reality applications as well as computer games. The game simulates a medieval village called SiXton that can be explored and experienced using gestures and speech for in put. SiXton's Curse utilizes multiple independent components for physical simulation, sound and graphics rendering, artificial intelli gence, as well as for multi-modal interaction (MMI). The compo nents are already an integral part of Simulator X's current version. Building on Hewitt's actor model, the Simulator X platform enables the developer to easily exploit the capabilities of modern hardware architectures. A state variable concept is implemented on top of the actor model to grant uniform and easy access to global states and values by using the internal mechanisms of the actor model. Communication via an asynchronous messaging in terface reduces component coupling. The scalability of the actor model provides a uniform concurrency paradigm on different levels of granularity as well as exchangeability of architectural elements and components.