By abstracting devices to Web resources, the Web of Things (WoT) fosters innovation and rapid prototyping in the Internet of Things (IoT): it enables developers to use standard Web technologies for creating mashups of Web services that perceive and act on the physical world (a.k.a. physical mashups ). In recent years, however, it has become apparent that current programming paradigms for Web development have important shortcomings when it comes to engineering IoT systems: static Web mashups cannot adapt to dynamic IoT environments, and manually mashing-up the IoT does not scale. To address these limitations, WoT researchers started to look for means to engineer WoT systems that are more autonomous in pursuit of their design objectives. The engineering of autonomous systems has already been explored to a large extent in the scientific literature on artificial intelligence. In this position paper, we distill that large body of research into a coherent set of abstractions for engineering autonomous WoT systems.