For a one-way message, use the clnt_send() function. No time-out is applied as the client sends a request to a server and does not wait for a reply.
For two-way messaging, use clnt_call(). The client remains blocked until the server sends a reply or an error status message, or until a time-out occurs at the client side.
The non-blocking feature enables you to send two-way and one-way calls together. If you use clnt_call() on the client side configured as non-blocking, that is, using the RPC_CL_NONBLOCKING I/O MODE, you get the following modified behavior. When a two-way request is sent to the buffer, all one-way requests already in the buffer are sent through the transport layer before the two-way request is processed. The time taken to empty the buffer is not counted in the two-way call timeout. For further information, see the clnt_control(3NSL) man page.