Logical Instantaneity and Causal Order:
Two ``First Class'' Communication Modes for Parallel Computing
by Michel Raynal
IRISA (Université de Rennes and INRIA)
France
raynal@irisa.fr
Abstract:
This talk will focuse on two communication modes, namely Logically
Instantaneity (LI) and Causal Order (CO). These communication modes
address two different levels of quality of service in message delivery.
LI means that it is possible 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
timestamp. So, there is a logical time frame in which for each
message, the send event and the corresponding delivery events occur
simultaneously. CO means that, when a process delivers a message,
its delivery occurs in a context where the receiving process knows all
its causal past. Actually, LI is a property strictly stronger than CO.
The talk will present these noteworthy communication modes. Their main
interest lies in the fact that they deeply simplify the design of
message-passing programs that are intended to run on distributed
memory parallel machines or cluster of workstations.
Keywords: Causal Order, Cluster of Workstations, Communication Protocol,
Distributed Memory,Distributed Systems, Logical Time, Logical
Instantaneity, Rendezvou
Last modified: Fri Jun 9 09:44:29 MET DST 2000