This paper is to study how to provide smart services by analyzing each service history based on Cloud computing in smart cities. Normally, users use each smart device to receive their services while they stay in a place. In case they move and visit to other place, the system prepares the service based on their services history. At that time, although the users had visited and had services in past, this visiting may ask other services. Then the existing system usually generates new service, and next it provides the service to the user. However, this method is inefficient, because the system has to accept the number of process whenever all users request the service. In this paper, it suggests the smart service model that it keeps users' services history, which had used them while the user stays to a place. The system catches the user's visiting with the user's contexts in the smart device. The model considers their plan/purpose based on old services, and it decides if they modifies them by editing extra services. It calls the system optimization and the suggesting method shows better efficiency after experimenting.

smart service, context, Smart City, cloud, optimization