Communication Protocols

The Library uses Remote Procedure Calls (RPC) to communicate between the host and the server. The specific transport protocol used is TCP. There are actually two transport protocols available UDP and TCP. Although UDP is faster than TCP, it has a limitation on the maximum datasize, and is designed to be connectionless and unreliable. In particular, UDP will not guarantee that packets are delivered in the order in which they were sent. Moreover, duplicate packets may be generated in the communication process. Consequently, we have chosen the TCP protocol. See man tcp and man udp to get more information on these topics. Check the man page for RPC to obtain information about Remote Procedure Calls. On the Paragon, nx_ message passing calls are used with the nx_ version of the library, while mpi_messing passing calls are used in the MPI version. Setting the communication language in the Makefile determines which is compiled. It should also be noted that the RPC daemon on the server side invokes threads.

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