Posting Comments (Security)

Hi, how do Facebook posts (status updates) / comments work in terms of security…

I was surprised to see that Facebook allowed me to post 3 status updates one after the other and then also allow me to post 20 comments on a status update all within 5 seconds

I have a comment feature on my website and i need a way of preventing users from spamming with comments (without use a captcha)

Users must be logged in to post a comment… so when a comments is being posted, should i just check to see if the same $ user_id posted a comment within the last 20 seconds… or can someone think of a more suitable method…

Thanks in advance for your help…

You can develop your code as to give restriction to not post same users post within 1 hour or more?

Well, youd have a file, script or class to handle posting comments. In there, set a session variable with the timestamp of the last comment.
Check the timestamp when posting new comments, control how much time has passed, if not enough time has passed, refuse to post the comment.

Should get you started.