摘要：The development of applications that adapt to the environment and remain running even when the user is moving or switching device, remains an open research challenge. In this article we present a view of the EXEHDA middleware and a new service created for dynamic adaptation. EXEHDA is service-oriented, adaptive and was conceived to support the execution of ubiquitous applications. The main concept in the proposed design for the middleware and for the application is context awareness expressed in an adaptive behavior. The middleware manages and implements the follow-me semantics for ubiquitous applications. This is also a key to provide functionality adapted to the constraints and unpredictability of the large-scale environment. To achieve this objective, EXEHDA employs various strategies in its services to allow the adaptation to the current context, such as on-demand adaptive service loading, and dynamic discovery and configuration. In that sense, EXEHDA provides services for distributed adaptive execution, context recognition, ubiquitous storage and access, and anonymous and asynchronous communications. To evaluate the new service proposed for dynamic adaptation we developed a case study, implementing an application in medical area. Analyzing the results we can see that the users found the application easy to use and usefulness for health workers at a hospital. This work is sponsored by RNP, FINEP and CNPq - Brazilian Foundations.
