Messages versus messengers in distributed programming

Messengers are autonomous objects, each capable of navigating through the underlying network and performing various tasks at each node. Messenger applications are written using navigational commands rather than the send/receive primitives of conventional message-passing approaches. In this paper we contrast the two programming styles. The navigational style generally results in a smaller semantic gap between abstract algorithm descriptions and their actual implementations, which makes programs easier to construct, understand, and maintain. Other advantages of the navigational programming style include the ability to compute in unknown or dynamically changing network topologies.