Now, whenever we need to pass a message to the XMPP server from the webapp, we stick it into a special Redis list. The proxy-component is now connected to the XMPP server and also connected to Redis. Using Redis’ BLPOP feature, the proxy-component ‘listens’ to the list, and forwards any new messages to the XMPP server. BLPOP is especially suited for this setup since it blocks the redis connection till a new item shows up in the list, making it quite zippy (otherwise you’d have to poll the list every few seconds, not as great or fast).
Why not using Redis Pub/Sub?
Original title and link: Rails to XMPP with Redis (NoSQL databases © myNoSQL)