Abstract. Typical sensor nodes are composed of cheap hardware because they have to be affordable in great numbers. This means that memory and communication bandwidth are small, CPUs are slow and energy is limited. It also means that all unnecessary software components must be omitted. Thus it is necessary to use application specific communication protocols. As it is cumbersome to write these from scratch every time a configurable framework is needed. Copra provides such an architectural framework that allows the construction of application specific communication protocol stacks from prefabricated components.