M facebook sex chat
One of the things I like most about working at Facebook is the ability to launch products that are (almost) immediately used by millions of people.
They'll get the message when they're back online.All they have to do to chat back is type a message to you in their chat window.Some people like to have a sound play every time they get a new message on Facebook Chat or any other IM or email program for that matter.When your contact replied their message will be displayed (more or less) instantly.Although the Facebook Chat app is easy to use, it is pretty basic.Click on the name of someone who has a green dot next to their name. Just type your message into the box, hit enter, and you've started a chat.
Send messages to your Facebook friends even if they're not online.
The next Facebook Chat tool is notifications which will let you know if you have any new Facebook notifications right from the tool.
The third tool in Facebook Chat is the actual chat tool.
The naive implementation of sending a notification to all friends whenever a user comes online or goes offline has a worst case cost of O(average friendlist size * peak users * churn rate) messages/second, where churn rate is the frequency with which users come online and go offline, in events/second.
This is wildly inefficient to the point of being untenable, given that the average number of friends per user is measured in the hundreds, and the number of concurrent users during peak site usage is on the order of several millions.
Just go to your Facebook page and you can start to chat on Facebook right away.