SISO Space Reference FOM - Tools and Testing

The Simulation Interoperability Standards Organization (SISO) Space Reference Federation Object Model (SpaceFOM) version 1.0 is nearing completion. Earlier papers have described the use of the High Level Architecture (HLA) in Space simulation as well as technical aspects of the SpaceFOM. This paper takes a look at different SpaceFOM tools and how they were used during the development and testing of the standard.The first organizations to develop SpaceFOM-compliant federates for SpaceFOM development and testing were NASA's Johnson Space Center (JSC), the University of Calabria (UNICAL), and Pitch Technologies.JSC is one of NASA's lead centers for human space flight. Much of the core distributed simulation technology development, specifically associated with the SpaceFOM, is done by the NASA Exploration Systems Simulations (NExSyS) team. One of NASA's principal simulation development tools is the Trick Simulation Environment. NASA's NExSyS team has been modifying and using Trick and TrickHLA to help develop and test the SpaceFOM.The System Modeling And Simulation Hub Laboratory (SMASH-Lab) at UNICAL has developed the Simulation Exploration Experience (SEE) HLA Starter kit, that has been used by most SEE teams involved in the distributed simulation of a Moon base. It is particularly useful for the development of federates that are compatible with the SpaceFOM. The HLA Starter Kit is a Java based tool that provides a well-structured framework to simplify the formulation, generation, and execution of SpaceFOM-compliant federates.Pitch Technologies, a company specializing in distributed simulation, is utilizing a number of their existing HLA tools to support development and testing of the SpaceFOM. In addition to the existing tools, Pitch has developed a few SpaceFOM specific federates: Space Master for managing the initialization, execution and pacing of any SpaceFOM federation; EarthEnvironment, a simple Root Reference Publisher; and Space Monitor, a graphical tool for monitoring reference frames and physical entities.Early testing of the SpaceFOM was carried out in the SEE university outreach program, initiated in SISO. Students were given a subset of the FOM, that was later extended. Sample federates were developed and frameworks were developed or adapted to the early FOM versions.As drafts of the standard matured, testing was performed using federates from government, industry, and academia. By mixing federates developed by different teams the standard could be tested with respect to functional correctness, robustness and clarity.These frameworks and federates have been useful when testing and verifying the design of the standard. In addition to this, they have since formed a starting point for developing SpaceFOM-compliant federations in several projects, for example for NASA, ESA as well as SEE

Enabling Reactive Streams in HLA-based Simulations through a Model-Driven Solution

Modern systems are exposing an ever increasing degree of complexity also due to the heterogeneity of the involved components. Distributed simulation is widely recognized as an effective tool to carry out verification and validation activities for heterogeneous and complex systems. Unfortunately, the use of distributed simulation frameworks and related implementation technologies require a proper modeling and simulation know-how, as well as a significant effort and software development skills. As a result, distributed simulation is not typically addressed by systems engineers who do not have the required expertise or background. The MONADS model-driven method has been introduced to overcome such limitations and provide systems engineers with the ability to properly carry out simulation-based verification and validation activities. The method specifically addresses the HLA (High Level Architecture) distributed simulation framework and introduces an automated approach to generate a significant portion of the HLA code from system models specified in SysML, the standard modeling language in the systems engineering field. The automatically obtained code is then to be finalized by a manual programming activity. This paper contributes to make easier and further reduce the effort of such a manual activity by integrating the reactive features of the RxHLA framework into the MONADS method. This integration enables the use of streams to effectively manage HLA-based asynchronous interactions. The paper describes the technical details of the various strategies that can be used to integrate RxHLA into the MONADS method, thus providing a significant degree of flexibility to MONADS users