Time for Reactive System Modeling

Abstract

Reactive systems interact with their environment by reading inputs and computing and feeding back outputs in reactive cycles that are also called ticks. Often they are safety critical systems and are increasingly modeled with highlevel modeling tools. The concepts of the corresponding modeling languages are typically aimed to facilitate formal reasoning about program constructiveness to guarantee deterministic output and are explicitly abstracted from execution time aspects. Nevertheless, the worst-case execution time of a tick can be a crucial value, as it decides the frequency in which the system can interact with its surroundings. An excessive tick Worst Case Execution Time (WCET) can lead to lost inputs or tardy reaction to critical events. Thus, the modeler has to make sure that the timing behaviour of the system under development meets the specifications. This thesis proposes a general approach to interactive timing analysis, which enables the feedback of detailed timing values directly in the model representation to support timing aware modeling. The concept is based on a generic timing interface that enables the exchangeability of the modeling as well as the timing analysis tool for the flexible implementation of varying tool chains. This aims at enhancing the comparability of tools and facilitates the sharing of benchmark model suites. The introduced approach is applicable not only to dataflow-based systems, but also to state-based systems. The latter is enabled by a concept for communicating analysis requests and responses for arbitrary code parts instead of a restriction to function granularity. The proposed timing analysis approach includes visual highlighting and modeling pragmatics features to guide the user to WCET hotspots for timing related model revisions. The approach is practically evaluated with an open-source Eclipse-based example implementation for the modeling language SCCharts, which includes a user study.

Interactive Model-Based Compilation

“…2014 While this work mainly illustrates how state-of-the-art tools can interactively help reactive system modellers to satisfy given deadlines, it also demonstrates the tool chain used to accomplish that goal. Fuhrmann continued the reactive system modelling research, which is not part of this work, and published the results elsewhere [Fuh17].…”

“…This section discusses the results from Motika [Mot17] and separates them from the contributions of this thesis. There has also been joint work on the topic of Interactive Timing Analysis [Fuh17], which can be seen as a demonstrator for the pragmatic and interactive modelling approach.…”

“…• The second related part from Motika [Mot17] covers the compilation of SCCharts using SLIC. Interactive Timing Analysis Fuhrmann used the model-based approach in her thesis [Fuh17] to facilitate timing analyses. In todays version of the compiler, which is explained in detail in Part I, the whole design flow and annotated visualization can be realized.…”