OMNeT++ is a discrete event simulation environment primarily designed for communication networks. In this paper we present an approach to enable OMNeT++ to simulate complex hierarchical process chains. Process chains are a common modeling paradigm in the logistics area for the analysis and optimization of large process chains and have been intensely used in many practical applications. Their evaluation is supported by the ProC/B toolset, a collection of software tools for modeling, analysis, validation and optimization of process chains. Here we describe how OMNeT++ has been integrated as a new simulation engine into the toolset. The integration has to get over some core problems to allow a smooth interaction between OMNeT++ and the other tools: In particular, the OMNeT++ model description of the logistics network should be kept manageable, it should reflect the entire model structure and non-standard performance figures, being relevant for an economic evaluation, should be ascertainable in order to satisfy the specific needs of the application area. The paper highlights the main steps of the automatic transformation of a hierarchical process chain model into a hierarchical model in OMNeT++. Furthermore, we show how the transformation has been validated and how detailed performance figures can be evaluated with OMNeT++.
When planning Service-Oriented Architectures requirements declared in Service Level Agreements (SLAs) have to be considered. SLAs cover functional as well as quantitative requirements like load levels, services rates and delay times. As external factors can influence distributed systems, SLAs have to include tolerances for quantitative requirements. Early design phases of SOA use analytic models to check functional properties. However, formalization of quantitative requirements in SLAs and their validation in analytic models is still a field of research. A challenge is the description of soft deadlines and the way delay times grow under different load levels. Network Calculus system theory can give bounds on delay times in systems. It has already been used to validate hard deadlines in networks and embedded systems. For its use in SOA models, soft deadlines and other aspects derived from SLAs have to be included. This paper introduces a new method to control delay times in Network Calculus models in order to specify quantitative requirements. The basic Network Calculus concept of arrival and service curves is extended with delay curves and their relationship is discussed.
This paper presents an approach to simulate complex hierarchical process chains resulting from large logistics networks in OMNeT++, a discrete event simulation environment designed for communication networks. For this purpose OM-NeT++ has been integrated as a new simulation engine into the ProC/B toolset which is designed for the analysis and optimization of large logistics networks. The paper highlights the main steps of the automatic transformation of a hierarchical process chain model into a hierarchical model in OMNeT++. Furthermore it shows how the transformation has been validated and how detailed performance figures can be evaluated with OMNeT++.
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