Messages versus messengers in distributed programming

Messengers are autonomous objects, each capable of navigating through the u nderlying network and performing various tasks at each node. Messengers app lications are written using navigational commands rather than the send/rece ive primitives of conventional message-passing approaches. In this paper we contrast the two programming styles. From a software engineering viewpoint , the navigational style generally results in a smaller semantic gap betwee n abstract algorithm descriptions and their actual implementations, which m akes programs easier to construct, understand, and maintain. In terms of pe rformance, Messengers programs are highly competitive with message-passing. We demonstrate these advantages using two concrete applications programmed using Messengers and PVM. (C) 1999 Academic Press.