A developer is designing a multi-tier web application and discovers a need to hide the details of establishing and maintaining remote communications from the client. In addition, the application…

A developer is designing a multi-tier web application and discovers a need to hide the details of establishing and maintaining remote communications from the client. In addition, the application needs to find, in a transparent manner, the heterogeneous business components used to service the client's requests. Which design patterns, working together, address these issues?