What are the possibilities in ruby for passing information from one 
process to another? Specifically, I'm thinking of messaging between a 
parent process and its forked child.

Right now I can think of some messaging primitives:
- TCPServer/TCPSocket
- UNIXServer/UNIXSocket (unstable?)
- IO.pipe (doesn't need port#)
- Process.kill (impossible to send data)

And some messaging libraries:
- DRb (standard)
- eventmachine (efficient?)

...what else? And, if anyone has the experience, what are the 
advantages/disadvantages of each in terms of speed, reliability, system 
resources?

Thanks,
Daniel