Developing software for mobile or ad hoc scenarios is very cost intensive. Different software and hardware platforms (e.g., digital cameras, PDAs, elec- tronic pens, mobile phones) are linked together via dif- ferent communication technologies (e.g., Infrared, Wireless LANs or cell phone networks). Often, mobile devices co-operate with desktop computers, thus commu- nication links between mobile ... [Show full abstract] and traditional infrastruc- tures have to be considered as well. Currently, the market for devices and communication technologies is rapidly changing. To be able to reuse software, even when the underlying communication infrastructure is modified or exchanged, applications should not be developed 'from scratch' but with the help of middleware platforms, which separate network related functions from the application. In this paper, we present the Network Kernel Framework (NKF), a middleware framework for small devices in mobile environments. Developers who want to integrate NKF support for new devices only have to realize an appropriate subset of services, thus NKF is suitable for devices with small memory and low computational power.