Aspect-awareness in the development of configurable system software

More than 98 percent of the worldwide annual production of microprocessors ends up in embedded systems – typically employed in goods of mass production, like cars, appliances, or toys. Such embedded systems are subject to an enormous hardware-cost pressure. System software for this domain has to cope not only with a broad variety of requirements and platforms, but especially with strict resource constraints. To compete against proprietary systems (and thereby to allow for reuse), a system-software product line for embedded systems has to be highly configurable and tailorable. However, this flexibility has to be provided in a way that meets the strict resource constraints. The state of the art for the overhead-free implementation of fine-grained configurability in system software is conditional compilation with the C preprocessor. However, this approach leads to scattered and tangled code and does not scale up. At the same time, the demands on configurability of system software are still increasing. AUTOSAR OS, a new industry standard for automotive operating systems, requires configurability of even fundamental architectural system policies, such as protection and isolation strategies. This thesis evaluates aspect-oriented programming (AOP) as a first-class concept for implementing configurability in resource-constrained systems. It shows that a well-directed, pragmatic application of AOP leads to a much better separation of concerns in the implementation of configurable system software – without compromising on resource thriftiness. Moreover, the suggested approach of aspect-aware operating-system development facilitates providing even fundamental architectural policies as configurable features. The suitability of AOP is evaluated with state-of-the-art operating systems from the embedded-systems domain. The practicability of aspect-aware operating-system development is validated by the design and development of the CiAO operating-system family, which is the first operating system that has been designed and developed with AOP concepts from the very beginning. CiAO combines a competitive implementation of the AUTOSAR-OS standard with a highly configurable architecture.