Due to the large success of wireless networks and portable devices, the pervasive computing paradigm is becoming a reality. One of the most challenging objectives to be achieved in pervasive computing environments is to allow a user to perform a task by composing on the fly the environment's service and resource components. However, existing approaches commonly assume that networked components have been developed to integrate in terms of interfaces and conversations, which restricts the user's ability to fully exploit the diversity of the pervasive computing components. In order to overcome this constraint, we propose a solution for ad hoc composition of pervasive computing components, based on theWeb services and SemanticWeb paradigms. The main feature of our solution is the ability to integrate on the fly a number of Web services' conversation fragments to reconstruct a conversation enabling the target user task.