Slotted-FIFO communication for asynchronous distributed systems

Communication protocols designed for database applications are not necessar ily suitable for other applications, like multimedia communication, due to the former's requirement of reliable and ordered communication, and the lat ter's ability to withstand occasional losses and misordering of messages as long as real-time communication can be supported. This paper presents the slotted-FIFO communication mode that supports communication primitives for the entire spectrum of reliability and ordering requirements of distributed applications: for example, FIFO as well as non-FIFO, and reliable as well as unreliable communication. It provides communication with a run-time vari able degree of reliability and/or ordering, Hence, the slotted-FIFO communi cation mode is suitable for applications that can work with relaxed reliabi lity and/or ordering constraints such as multimedia applications. The proto col is simple and has low overheads. As FIFO ordering is not required for a ll messages, message buffering requirements are considerably reduced. Also, message latencies are lower. We demonstrate such advantages by means of a simulation study. A low overhead protocol implementing slotted-FIFO communi cation is also presented. The protocol incurs a small resequencing cost.