Streaming, Daemons, Cron, the basics?

Hey there,

I’ve finally had a second to look into streaming, daemons, and cron
tasks and all the neat gems built around them! But I’m not clear on
how/when to use these things.

I have a few questions on how/what they are used for that maybe you
could shed some light on:

  1. If I wanted to have a website that stayed constantly updated,
    realtime, with my Facebook friends’ activity feeds, and my Twitter feed,
    would I just create some custom streaming implementation using the
    Daemon gem, the ruby-yali gem for streaming the content, and the
    Whenever gem for every 10 seconds checking the websites to see if
    anything has changed? Is that how it would work? Or is it
    typically/preferably done differently?

  2. If I wanted any sort of live/real-time content updating, so that my
    site had up-to-the-minute Amazon book reviews on my favorite books for
    instance, would I use that Daemon/ruby-yali/Whenever combo or something
    like it?

  3. Are 1 and 2 too processor intensive? Is there a better way you do
    it, a better way for live content streaming? I’m thinking about just
    sending a request every 30 seconds or so, getting the json/xml result,
    using nokogiri to remove the stuff I don’t need, and then just going
    through the small list of comments/books/posts/etc., and somehow sending
    that to a View.

I guess it all boils down to the question:

How does real-time streaming of the latest content of some website work?
…so if someone is on my site, they can see in real time the new
message or new book that just came out?

Thanks for helping me out, I really appreciate it.