In the context of online-and symbiotic simulation, the precise initialization of simulation models based on the state of the physical system is a fundamental requirement. In these simulations, the simulation model typically serves as an operational decision support tool. Obviously, it can therefore not start empty and idle. The accurate capturing of initial conditions is fundamental for the quality of the model based predictions. In literature, it is only generally stated that the simulation model must maintain a close connection with the physical system. Our work systematically investigates which data from the physical system is needed for initialization, how it shall be transferred into the simulation model in a standardized way, and which potential problems must be solved in the simulation system to adequately initialize its model elements. We present a solution based on the core manufacturing simulation data (CMSD) standard, suggest necessary extensions and demonstrate a prototypical implementation.

Research on systems of autonomous agents, called multiagent systems (MAS), has received much interest in the domain of (distributed) artificial intelligence in recent years. MAS are most suitable for the development of distributed applications within an uncertain and dynamically changing environment (Logan 2005). For validation of such systems agent based simulation is a new modeling paradigm not limited to systems which qualify as MAS by default. The focus of the work presented here is on scalability aspects of simulation environments for agent based simulations. Scalable solutions are required, as complex models require the capability to simulate hundreds or more complex deliberative agents. This is a capability which is often lacking in existing simulation environments for agents. We investigate different aspects which influence scalability and present a solution for enabling a scalable and efficient distributed simulation of agent-based models based on an adapted optimistic synchronization protocol which limits the level of optimism by using knowledge about agent interaction patterns.

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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...

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