—Sensor network deployments, such as smart cities and smart logistics, are evolving towards open infrastructure on top of which multiple parties deploy and make use of each other’s application software. Of vital importance in such distributed settings, is an agreement on message semantics and contents. Yet, the current state-of-the-art in sensor programming typically remains low-level in terms of messaging, and lacks support for coordination across platforms and stakeholders. We present TALKSENS, a message definition framework that facilitates development of correctly interacting application logic by means of a shared data model, a message description language and serialisation code generation. Additionally, integration of TALKSENS with an existing component model results in runtime retrievable message definitions that facilitate third-party interactions. Our evaluation shows that message sizes, software sizes and middleware overhead remain well within the bounds of sensor networ...