How do I use subprocess.Popen to connect multiple processes by pipes?

echo "input data" | awk -f script.awk | sort > outfile.txt

p_awk = subprocess.Popen(["awk","-f","script.awk"],
                          stdin=subprocess.PIPE,
                          stdout=file("outfile.txt", "w"))
p_awk.communicate( "input data" )

import subprocess

awk_sort = subprocess.Popen( ["-c", "awk -f script.awk | sort > outfile.txt" ],
    stdin= subprocess.PIPE, shell=True )
awk_sort.communicate( "input datan" )
awk_sort.wait()