Logically instantaneous communication on top of distributed memory parallel machines

Communication is Logically Instantaneous (LI) if it is possi- ble to timestamp communication events with integers in such a way that (1) timestamps increase within each process and (2) the sending and the delivery events associated with each message have the same times- tamp. So, there is a logical time frame in which for each message, the send event and the corresponding delivery events occur simultaneously. li is stronger than Causally Ordered (CO) communication, but weaker than Rendezvous (RDV) communication. This paper explores Logically Instantaneous communication and provides a simple and efficient pro- tocol that implements LI on top of asynchronous distributed systems. LI is attractive as it includes CO and provides more concurrency than RDV. Moreover it allows to adopt the following approach: first design a distributed application assuming Rendezvous communication, and then run it on top of an asynchronous distributed system providing only LIcommunication.