The Internet of Things is an ideal world in which all computing devices from all over the world connect and exchange data through the Internet. This new scenario demands contextaware systems to evolve with new characteristics; thus, brings new challenges for system developers in system development. While addressing these challenges, this paper presents a system design approach based on a stack of 16 services specialized for context-aware systems. The approach enables system developers to focus more on services than hardware and software components. The case study of a smart irrigation context-aware system, also presented in this paper, is an example of using this design approach in practice.