When to use sockets over Fifo for Client-Server IPC?

Question

Having looked at code for sometime now, I see most coders have used sockets for IPC over Pipes (Or FIFO to be specific).

Considering that there's only one client and one server, isn't it better to use FIFO over sockets? Please educate me in this matter.

Answer 1

FIFO has following benefits:

• they are atomic for writing if data len is less than PIPE_BUF
• splice is almost garanted working with SPLICE_F_MOVE (no user space data copy kernel will move data between pipes)
• they are more easy to set up in comparison with sockets

But on the other hand it is unidirectional i.e. you most likely need 2 separate fifo:

• for writing data from client to server
• for writing data from server to client

Or use one fifo but reopen it as need i.e. get data on server - reopen fifo WR_ONLY on server, reopen fifo RD_ONLY on client, get data on client and do vice versa after reading data from server.

http://man7.org/linux/man-pages/man7/pipe.7.html

Answer 2

• Socket is bi-directional, pipe/fifo is uni-directional.
• Socket can be stream or datagram, pipe/fifo are always streams.
• Socket and fifo do not require related processes, whereas unnamed pipes do.
• Socket can handle more than one peer.