In order for a Rails backend app to notify a SproutCore front-end app about changes to the database, we'll need some sort of comet, long-poll, websocket style communication infrastructure.

There don't seem to be any projects which implement this directly in rails... it seems all have taken the path of having rails push messages to a 3rd-party comet server which then pushes those messages out to whoever is listening and interested.

There are quite a few comet servers available:

• CometD
  • CometD is built upon jetty, so it should be fairly stable and fairly fast. Writing our own customized channel handlers and services would be done in Java and looks pretty easy and straightforward. No examples for integrating with rails.
• Orbited
  • Written in python. Has examples for integrating with Rails.
• Faye
  • We're already using a customized version of Faye. Merging in the current work on Faye may be difficult.

There are some others listed here: http://cometdaily.com/maturity.html