Ubiquitous computing has developed with mobile computing technology. With the recent advances in mobile computer technology and wireless network, the nature of the services proposed to the users is moving towards mobile and context-aware services. On account of such moving, applications and services in mobile and ubiquitous environment must be aware of their changing environments and adapt according to changing contexts. However, developing such systems providing context-aware applications or services is still a complex and time-consuming task. Therefore, we introduce architecture of Context-Aware Service Middleware (CASM) that will provide a middleware-level support for building and rapid prototyping of context-aware services and describe interactions based on the architecture.