Dependability and performance analysis of modern systems is facing great challenges: their scale is growing, they are becoming massively distributed, interconnected, and evolving. Such complexity makes model-based assessment a difficult and time-consuming task. For the evaluation of large systems, reusable submodels are typically adopted as an effective way to address the complexity and to improve the maintainability of models. When using state-based models, a common approach is to define libraries of generic submodels, and then compose concrete instances by state sharing, following predefined "patterns" that depend on the class of systems being modeled. However, such composition patterns are rarely formalized, or not even documented at all. In this paper, we address this problem using a model-driven approach, which combines a language to specify reusable submodels and composition patterns, and an automated composition algorithm. Clearly defining libraries of reusable submodels, together with patterns for their composition, allows complex models to be automatically assembled, based on a high-level description of the scenario to be evaluated. This paper provides a solution to this problem focusing on: formally defining the concept of model templates, defining a specification language for model templates, defining an automated instantiation and composition algorithm, and applying the approach to a case study of a large-scale distributed system.
Abstract-A dramatic shift in system complexity is occurring, bringing monolithic system designs to be progressively replaced by modular approaches. In the latest years this trend has been emphasized by the System of Systems (SoS) concept, in which a complex system or application is the result of the integration of many independent, autonomous Constituent Systems (CS), brought together in order to satisfy a global goal under certain rules of engagement. The overall behavior of the SoS, emerging from such complex interactions and dependencies, poses several threats in terms of dependability, timeliness and security, due to the challenging operating and environmental conditions caused by mobility, wireless connectivity, and the use of off-the-shelf components. Referring to our experience in mobile safety-critical applications gained from three different research projects, in this paper we illustrate the challenges and benefits posed by the adoption of an SoS approach in designing, developing and maintaining mobile safety-critical applications, and we report on some possible solutions.
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