Component-based software platforms like OSGi (TM) facilitate the development of complex software. As software systems become more complicated, tool support is often a necessity for assuring the conformance between designed and implemented architectures. We present ARTOS, an architecture toolkit to facilitate the design and conformance analysis of the software running on the OSGi platform. The toolkit consists of an architecture editor and a conformance analyzer. The editor provides definition constructs specific to the OSGi platform and allows architects to wire components by using different kinds of dependency relations. The analyzer adopts a model-based approach, namely reflexion modeling technique, where the concrete and implemented architecture models are compared with each other to build a model of conformance. The use of ARTOS is demonstrated on an industrial case study. Finally, we discuss how the reflexion model technique can be extended to provide users with a conformance view that takes different types of dependencies into account.