config

cfgRole MASTER
cfgHostName localhost

Remoting.hs

{-
One process starts the master process
Other start do-nothing process
master distributes the work among the other processes
-}

module Main where

import Remote
import Control.Monad

main :: IO ()
main = remoteInit (Just "config") [] initialProcess

{-
the argument defines the role. All nodes run from the same executable, the config defines which 
role the node should assume and then this function branches off depending on the role.
-}
initialProcess :: String -> ProcessM ()
initialProcess "MASTER" = masterProcess
initialProcess "SLAVE" = slaveProcess
initialProcess role = error $ "Unknown role " ++ role

masterProcess :: ProcessM ()
masterProcess = do
  peers <- getPeers
  let slaves = findPeerByRole peers "SLAVE"
  myPid <- getSelfPid
  forM_ slaves (receiveMessage myPid)

receiveMessage :: ProcessId -> NodeId -> ProcessM ()
receiveMessage myPid node = do
  Just pid <- nameQuery node "main"
  send pid myPid
  msg <- expect
  say $ "message: " ++ msg

slaveProcess :: ProcessM ()
slaveProcess = do 
  nameSet "main"
  pid <- expect
  send pid "PONG"