  A smart space offers entirely new opportunities for end users by adapting
services accordingly to make life easy. A number of architectural designs have
been proposed to design context awareness systems and adaptation behavior.
However, the quality of the system depends on the degree of satisfaction of the
initials needs. In this paper, we discuss three main indicators of quality
design for smart spaces that are strongly related to the context modules and
reasoning process: functionality, reusability and changeability. A general
layered architecture system is presented to define the principal components
that should constitute any context aware adaptive system.
