Communication between two programs on unix

[morden]

I want to connect the standard output of the tkinter app to the stdin of 
the motif app to return results and connect stdout of motif app to the
input of the tkinter app. Is that doable? I suppose this is what 
os.popen will do. Right?

Scenario #1: I run my tkinter program with no flags and it
	popens motif app it should communicate with

Scenario #2: I connect to a remote system using 'cu' from uucp package
	and run a unix app there communicating to my tkinter app spawned
	with ~+ sequence in cu (that's what you use to run rz/sz over cu 
session, right?)

Scenario #3: I use ssh to get into a remote system and run a unix app 
there. I have the following question about this scenario: How would I 
connect input of the tkinter program to the output
of the motif app and vice versa in this case? Is there any way to tell 
ssh client to do this or I would have to modify my apps to have support 
for ssl/tls?