Best way to send JSON request/get a response from controller?

Hello Friends,

What is the best way to send json from your controller, and await for a
response? Ajax? Ruby’s net/http?

The JSON server that I am sending the request to only accept POST
and sends a POST back. If I use Ajax, is it possible to get the POST
response? Is there a scriptaculous or YUI function that handles this

Thank you for your help -