Epsilon is a testbed for monitoring distributed applications involving heterogeneous computers, including microcomputers, interconnected by a local area network. Such a hardware configuration is usual but raises difficulties for the programmer. First, the interprocess communication mechanisms provided by the operating systems are rather cumbersome to use. Second, they are different from one system to another. Third, the programmer of distributed applications should not worry about system and/or network aspects that are not relevant for the application level. The authors present the solution chosen in Epsilon. A set of high-level communication primitives has been designed and implemented to provide the programmer with an interface independent of the operating system and of the underlying interprocess communications facilities. A program participating in a distributed application can be executed on any host without any change in the source code except for host names.>

In this paper, we study a model of the Basic Block Protocol of the Cambridge Ring. The model is close to the real behavior so that, with statistically, identical stations and light or moderate load assumptions. we obtain good approximate results of the Ring characteristics. These results are partially validated by a simulation.

In this paper an M/G/∞queue is considered that receives a stream of numbered tasks. Results are derived concerning the probabilistic properties of the reordering done by the queue.