Sockets again
Keean Schupke
k.schupke@imperial.ac.uk
Tue, 29 Apr 2003 17:43:30 +0100
Hi,
The problem is not with the haskell, but with telnet, which uses
line buffered output itself.
Try the following:
module Main(main) where
import IO
import Network
main = do
socket <- listenOn (PortNumber 15151)
(handle,hostName,_) <- accept socket
hSetBuffering handle (BlockBuffering (Just 4096))
putStr ("Accepted: "++hostName++"\n")
c <- hGetLine handle
putStrLn (show c)
telnet to this, type a line and hit return ... should print the line.
Regards,
Keean Schupke
George Russell wrote:
> The attached short program (compile with "ghc VServer.hs -o v -package
> net")
> is supposed to set up a server on port 15151, wait for a connection, read
> the first character from the connection, and print it out. Unfortunately
> if I test it, by running it, and starting up "telnet [machine] 15151"
> somewhere else, and then type some random text, EG "foo[RETURN]", it does
> not work. It looks as if the problem is that VServer.hs issues the
> command
> hSetBuffering handle (BlockBuffering (Just 4096))
> on the connection, because when I change it to
> hSetBuffering handle NoBuffering
> the program works.
>
> However this is not what I want to do!! Because setting NoBuffering
> on the
> handle is going to mean that when the Server *outputs* something, it will
> potentially be done very expensively character by character. How do I
> get block buffering on the Server's output, but not have input to the
> server held up?
>
> The same thing seems to happen with client Handles by the way.
>
>------------------------------------------------------------------------
>
>-- Test program for server using GHC Socket library.
>module Main(main) where
>
>import IO
>import Network
>
>main =
> do
> socket <- listenOn (PortNumber 15151)
> (handle,hostName,_) <- accept socket
> hSetBuffering handle (BlockBuffering (Just 4096))
> putStr ("Accepted: "++hostName++"\n")
> c <- hGetChar handle
> putStrLn (show c)
>
>
>