Engineering look-ahead in distributed conversations

This paper investigates the effects of relaxing the synchronisation embedded in “classical” conversation schemes. Look-ahead conversation scheme enables the synchronisation mandated by conversations to be performed concurrently to other normal system activities, and thereby provides scope for enhancing system performance. In this paper, we take the view that permitting look-ahead must guarantee that executions with and without look-ahead be equivalent for identical inputs and run-time conditions. We identify and formulate the necessary condition for meeting this objective. We then present two schemes for realising this condition. The first scheme is based on piggybacking extra information onto ongoing messages, and the second one is a message passing protocol requiring each participant to send one message to every other participant of the conversation. These schemes do not require a conversation participant to know a priori all participants of the conversation, bur only those it is designed to interact with, during the conversation