How to show continuous real time updates like facebook ticker, meetup.com home page does?
You could use a poll, long-poll or if you want a push system. Easiest would be a poll. However, all solutions require client side coding.
Performance impact depends on your solution. Easiest to implement would be a poll. A poll with short frequency does effectively a request every, say 100ms ot simulate real time. A long-poll would be of less impact, but it would keep open a lot of request during a more or less time.
How to show continuous real time updates in browser like facebook ticker, meetup.com home page does? In python, PHP, node.js and what would be the performance impact at the server side ?
Also how could we achieve the same update thing if the page is cached by an CDN like akamai?