Analyzing Scenario-based Specifications

OData support
Dr. Micskei Zoltán Imre
Department of Measurement and Information Systems

The complexity of IT and safety-critical systems has increased rapidly in recent years. Due to the complexity of the systems in system engineering, the model-based paradigm has become the decisive approach. The goal of the approach is to automatically derive configuration, documentation and implementation from high-level models. In this way different analysis methods can be applied on the high-level models. Finally, consistency can be checked and the platform-specific implementation can be generated automatically.

In the thesis, I analyze the often used scenario-based specification languages for modeling communication of system components. The advantage of these languages is that the communication sequences of different components can be analyzed without actual implementation details, using only the component-level design models. In this way inconsistent behaviors and design flaws can be identified in the early design stages. These flaws are usually due to ambiguous requirements and specification.

Besides the overview of the frequently used scenario-based specification languages, I evaluate the existing tool support for them by comparing the tools from the level of standardization of the modeling language, that is used by the tool, and the analysis and design functionalities the tool offers.

Distributed embedded safety-critical systems can be developed by statechart formalism. Gamma Statechart Composition Framework~\cite{graics-bsc, graics-tdk} is a tool which supports the model-driven design and analysis of hierarchical, \mbox{component-based} reactive systems. However, it is not possible to specify the communication through a given port of a component.

Hence I enrich the Gamma Framework with a model-based scenario language: Gamma Scenario Language (GSL). The formalism of GSL is based on Live Sequence Charts. I designed the abstract and concrete syntax of GSL using open-source modeling technologies. I also defined the formal operational semantics of the language by transforming scenarios into finite automata.

I propose and implement a scenario compatibility validation workflow which finds ambiguous traces in scenario definitions and then back-annotates these traces to the scenario editor to notify the engineer about the ambiguities.

Finally, in order to evaluate the applicability and the integrity of GSL to the Gamma Framework, I apply the language on a model railway case study. Then I perform several measurements, in order to get a preliminary overview for the runtime performance of the scenario compatibility validation workflow.


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