Multi-Subsystem Protocol Architectures: Motivation and Experience with an Adapter-Based Approach

Protocol software is often difficult, cumbersome, and expensive to implement and test in today's computing environments. To reduce this difficulty, several things are done: communications software is commonly subdivided into layers and organized into a protocol graph; it is developed within a protocol or networking subsystem; and it is often ported rather than developed from scratch. Inherent differences in the multitude of protocol subsystems offer a dizzying array of features, functionality, and drawbacks; their differences often reduce the portability and efficiency of protocol code. In this paper, we consider the differences in subsystems and their effect on the portability and performance of protocol implementations. We propose an approach for combining the `better'' features of protocol subsystems by constructing protocol graphs composed of protocols residing in different subsystems