Distributed simulation is the execution of a scenario by simulations running on multiple host computers. Each simulation is usually responsible for simulating the behavior of one or more players (“entities”) in the scenario. The simulations exchange entity state and entity interaction data using a computer network and an agreed-upon communications protocol.

FLAMES® supports distributed simulation by providing built-in, customizable support for the High Level Architecture (HLA) (described below) and the Distributed Interactive Simulation (DIS) standards. Because each standard is supported independently, FLAMES can participate in a DIS and an HLA exercise simultaneously. FLAMES also has other capabilities that support interactive and analytical simulation.

High Level Architecture (HLA)

The High Level Architecture (HLA) was developed under the leadership of the United States Department of Defense to support interoperability between different simulations. HLA supports interoperability by specifying a set of standards that govern the exchange of information between simulations as they execute their respective scenarios. Multiple simulations executing concurrently and exchanging data in accordance with HLA standards are referred to as an HLA federation.

The FLAMES HLA option allows FLAMES-based simulations to communicate with other simulations in an HLA federation according to HLA standards. Various windows in FORGE allow the specification of HLA exercise parameters and the supplemental, HLA-related attribute data required for each player in the scenario. With HLA enabled, FLAMES will automatically communicate with other properly configured simulations during scenario execution.

Simulations in an HLA federation communicate with each other using middleware referred to as a Runtime Infrastructure (RTI). RTI software is not included with FLAMES; it is available from a number of sources and must be obtained separately. FLAMES has been tested successfully with the RTIs available from MÄK Technologies® (HLA 1.3) and Pitch Technologies (pRTI 1.3). FLAMES can participate in HLA federations using HLA IEEE 1516 and HLA Evolved using readily available adapters.

In HLA, information is exchanged among simulations within a federation using instances of the object and interaction classes defined in a Federation Object Model (FOM). FLAMES is completely independent of any particular FOM. All FOM-specific processing occurs in special software objects that are developed separately and plugged into FLAMES. This allows FLAMES-based applications to be modified easily to support any FOM.

The HLA Option is bundled with several HLA software objects that provide support for a subset of the Simulation Interoperability Standards Organization (SISO) Real-time Platform Reference (RPR) FOM. As a result, FLAMES can participate in many HLA federations that use the RPR FOM right off the shelf without any software development.

The HLA option includes the source code to all of the bundled HLA software objects and everything you need to add support for additional FOMs.

Note: HLA is supported on computers running various versions of the Windows operating system. It is not supported on computers running the Linux operating system.


The HLA option is enabled without a runtime license in a FLAMES Runtime Suite application if the application is executing with only the bundled components loaded. Therefore, you can try it out using the free copy of the Runtime Suite. If custom component plug-ins are loaded, a runtime license to the HLA option is required to enable the option. Runtime licenses must be purchased separately. In addition, ALL of the custom component plug-ins loaded by the application must have been developed on computers that were licensed for the HLA development option.

An HLA option development license is required in order to create custom component plug-ins using the FLAMES Development Suite that support the option. Development licenses must be purchased separately. As stated above, the functionality of the HLA option is enabled in an application only if ALL of the component plug-ins loaded by the application were developed on computers that were licensed for the HLA development option.