Component-based software design of embedded real-time systems

Sammanfattning: Embedded systems have become commonplace in today's society and their complexity and number of functions are steadily increasing. This can be attributed to the unceasing advances in the microprocessor technology and the continuous delivery of more powerful and power-efficient microprocessors, which, in turn, allows more elaborate software implementations. Consequently, there is a strong interest in finding methods and tools that support flexible and efficient development of embedded software. Since these qualities are typically attributed to component-based design it makes sense to develop new design techniques targeting embedded systems based on components. This thesis aims to adapt the traditional component-based design approach for development of embedded real-time software. Component-based design relies on the existence of consistent and coherent models of individual components that can be composed to model the whole system. However, it can be argued that the special characteristics of embedded systems make such modeling challenging. One reason is that embedded systems typically exhibit a strong integration between hardware and software, which leads to a need for a common design space, or at least the possibility to create consistent models of both hardware and software components of an embedded system. Another reason is that the majority of embedded systems can be viewed as real-time systems and therefore it is necessary to express timing requirements alongside functional properties in the model. In order to overcome these difficulties, we adopt a reactive perspective, in which the functionality of both hardware and software is described in terms of time-constrained reactions of reactive objects. This enables capturing the complete functionality of the system (hardware and software) along with timing requirements in a single model.The reactive view lies behind the modeling framework for embedded real-time systems and the component-based software design methodology presented in this thesis. The methodology allows both functional and timing properties of a system model to be preserved during implementation process by means of a seamless transition between a model and an implementation, whereas the modeling framework enables the developer to offer platform-independent correctness for real-time systems, provided that the software can be scheduled on a given hardware platform. Further, this thesis includes a case study, in which the methodology is used for designing a real-life system. The case study demonstrates the potential of the methodology to bring the benefits of classical component-based design to the realm of embedded systems.