Note: this is the completed version of lecture Client.

Concurrency client

This module goes with the Concurrency lecture. It implements a network client that communicates with a server using sockets.

> module Client (local, client, send) where

This module uses the Network.Socket library, which provides basically the same interface to OS sockets as in C.

> import Network.Socket hiding (send)
> import System.IO

> -- | IP address of the local host
> local :: HostName
> local = "127.0.0.1"

> -- | Start the client given an IP address and a port. The port should
> -- be a string number > 1024
> client :: HostName -> ServiceName -> IO Handle
> client ip port = do
>   (sa:_) <- getAddrInfo Nothing (Just ip) (Just port)
>   sock   <- socket (addrFamily sa) Stream defaultProtocol
>   connect sock (addrAddress sa)
>   handle <- socketToHandle sock WriteMode
>   hSetBuffering handle (BlockBuffering Nothing)
>   return handle

> -- | send a message to the server
> send :: Handle -> String -> IO ()
> send h c = do
>   hPutStrLn h c
>   hFlush h

CIS 5520: Advanced Programming

Fall 2023

Concurrency client