The Road to COTS-Interoperability: From Generic HLA-Interfaces Towards Plug-and-Play Capabilities

Abstract

Interoperability between commercial-off-the-shelf (COTS) simulation packages (CSPs) is a topic which has been discussed for many years without a solution. With the advent of the High Level Architecture for Modeling and Simulation (HLA) for the first time a real industry standard has been made available which promises interoperability for a wide range of simulation systems and applications. Successful attempts to integrate HLA interfaces into different simulation packages have been made in the past. However, these interfaces typically place a significant overhead on the simulation developer. Also, as often a generic HLA interface is provided, different HLA interfaces for different simulation packages are not necessarily interoperable per se, as there are different possible ways to use HLA for the same task. This article addresses these issues and discusses interoperability solutions based on and beyond of HLA. It further investigates and comments the interoperability reference solutions put forward by SISO's COTS Simulation Package Interoperability Product Development Group. MOTIVATIONAfter the initial definition of the HLA it soon became obvious that its applicability was not limited to military simulation applications. However, it was also obvious to all researchers involved in that area, that there would be major differences between both military and non-military simulation communities. One major difference is in the way how simulations are developed. While in the military community simulations are often developed in languages such as C++ or Java, in the civilian simulation community, the use of commercial-off-the-shelf simulation packages (CSPs) (e.g. Arena, Extend, GPSS/H, Pro Model, Simul8, SLX, etc.) is commonplace. These simulation tools satisfy the need to develop models rapidly and cost-effectively.These different approaches for developing simulations also apply to HLA. While it is rather straightforward to directly access and use HLA in a simulation developed in C++, alternative means had to be developed for allowing HLA usage from a CSP (Strassburger 2001).Initial solutions have integrated HLA into these simulation packages by providing a simulation system specific HLA interface for the individual systems. Some of these interfaces (e.g., the HLA interface for SLX) were generic in the sense of being usable almost as flexibly as the native HLA application programming interface (API). Others were limited to a specific HLA use patterns.Section 2 of this paper discusses some of these solutions in further detail and explains the differences and problems associated with them.As the general HLA-enablement of simulation packages has been proven possible, it could be assumed that the solution to the interoperability issue of CSPs is that easy: each vendor simply needed to provide their system with a generic HLA interface.Reality, however, is more difficult (Taylor et al. 2002). The following facts indicate that more standardization efforts are needed to provide true plug-and-play-like and easy-to-use interoperab...

Distributed Modeling of Discrete Event Systems

“…from the commercial simulation software tools is not usually possible. Therefore, the enhancement of HLA with additional complementary standards [51] and the definition of a standard language for CSPs represent relevant and not yet solved technical and scientific challenges ( [25], [49], [50] …”

“…[12], [8], [11], [9], [10], [20], [28], [29], [30], [33], [74], [75] , [48], [50], [47], [49], [58], [53], [59], [56], [68], [70], [68], [73] and [71]). These papers can be considered as introductory to the topic of distributed simulation in civilian domain.…”

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“…Currently, there are six IRMs that describe the distributed simulation requirements for a range of scenarios, one Data Exchange Representation (entities) and one Interoperability Framework to support entity exchange (IRM Type I, Asynchronous Entity Transfer) [24,25]. Recent work on CSPI standards include Wang, et al [26] who study possible implementations of the Type II IRM Synchronous Entity Passing, Taylor, et al [27] and Gan, et al [21] investigate the use of CSP distributed simulation in engine manufacturing and semiconductor manufacturing respectively.…”

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“…But another major difference is in the languages selected to develop the simulation applications. While in the non-military simulations the commercial-off-the-shelf simulation packages (CSP) are widely used, in military environments the simulation applications are almost always developed in C++ or Java ( [10]). In fact, the SISO CSPI PDG standards are defined only for simulations based on CSP (Arena, Flexim, Simul8, etc) ( [10]).…”

“…While in the non-military simulations the commercial-off-the-shelf simulation packages (CSP) are widely used, in military environments the simulation applications are almost always developed in C++ or Java ( [10]). In fact, the SISO CSPI PDG standards are defined only for simulations based on CSP (Arena, Flexim, Simul8, etc) ( [10]). Therefore, the military simulation community recently has understood the importance of defining their own Interoperability Reference Models, taking into account the SISO CSPI PDG standards and the specific features of the military environments and applications.…”