Making XTP Responsive to Real-Time Needs

Conventional transport protocol standards do not adequately support distributed real-time systems. An ideal protocol would ensure that at all times the communications subsystem is working on the task (message) of the most value to the overall system. In this report we investigate how to develop a flexible and potent discrimination scheme based on importance, an abstract concept that measures the degree to which a task contributes to the overall system goal. We examine typical communication subsystems for what can and can not be expected from such a policy. We review our chain of reasoning for producing several schemes with varying degrees of complexity and usefulness. Finally, we look at the Xpress Transfer Protocol as a case study of a transport layer protocol in development, and describe and critique the methods proposed for making it responsive to special needs through a discrimination policy based on the importance of the messages it must process.