Wireless sensor networks have become a very attractive research topic in recent years. Many academic and professional research groups made efforts to construct operative hardware devices and sophisticated software to meet the special conditions in their projects. But still there has been little done to create a general structure for smart sensors to cooperate and to offer their services to human or software clients. In this paper we present first results of our investigations in this topic. As a test scenario and source of inspiration we set up a sensor network prototype in an office situation, where the physical environment should be measured and adjusted according to specific conditions. In particular the light and humidity state of potted plants within an office should be autonomously adjusted to the plants special needs as most research associates in our lab forget to care for their plants on a regular basis. On the basis of this prolific scenario we introduce a first stage middleware system architecture providing service distribution and accomplishment within wireless sensor networks. Core components of the architecture have been implemented in hardware and software to show the feasibility and abilities of our approach.