hello.py

import sys
print "HELLO WORLD !!!"
 
for line in sys.stdin:
     print line

process.py

#!/usr/bin/env python

# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

from twisted.internet import protocol
from twisted.internet import reactor

class MyPP(protocol.ProcessProtocol):
    def connectionMade(self):
        print "connectionMade!"
        '''
        for i in range(self.verses):
            self.transport.write("Aleph-null bottles of beer on the wall,\n" +
                                 "Aleph-null bottles of beer,\n" +
                                 "Take one down and pass it around,\n" +
                                 "Aleph-null bottles of beer on the wall.\n")
        self.transport.closeStdin() # tell them we're done
        '''
        #pass
    def outReceived(self, data):
        print "outReceived! with %d bytes!" % len(data)
        print data
        self.transport.write("SAME TO YOU")
        self.transport.closeStdin() # tell them we're done

    def errReceived(self, data):
        print "errReceived! with %d bytes!" % len(data)
    def inConnectionLost(self):
        print "inConnectionLost! stdin is closed! (we probably did it)"
    def outConnectionLost(self):
        print "outConnectionLost! The child closed their stdout!"

    def errConnectionLost(self):
        print "errConnectionLost! The child closed their stderr."
    def processExited(self, reason):
        print "processExited, status %d" % (reason.value.exitCode,)
    def processEnded(self, reason):
        print "processEnded, status %d" % (reason.value.exitCode,)
        print "quitting"
        reactor.stop()

pp = MyPP()
reactor.spawnProcess(pp, "python", ["python", "-u", "hello.py"], {})
reactor.run()