We introduce one more layer of indirection between application and transport layers for building new types of applications in future networks with some slight modifications on the current Internet architecture. In this layer, end-to-end transport flows are identified by the pairs of source-destination host ID, port number and protocol, and some transport flows among multiple terminals associated with one specific application can be grouped and managed as "session.'' This layer can provide the common framework for realizing various types of applications such as group communication and session mobility and so on. Thus we will show the concept and the structure of this new layer architecture in detail. Moreover, we explain the collaboration of this new layer and "association layer'' proposed earlier to flexibly handle application flows in the environment of multiple terminals with multiple network interfaces.