Software that runs in the network environment is facing with many challenges. One of them is the dynamic feature of the network. To keep the quality of service, the service entity needs to adapt promptly to the changing environment. The traditional system software, operating system, which is used mainly to manage the hardware resources of computer, doesn?t provide enough support for application adaptation at runtime. This paper introduces a middleware based approach that enhances the adaptability of software system. The key contribution of the proposed approach is that it clearly separates the adaptation program from the function program at runtime. The past, current and future work of MASS are introduced also.