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.Browse Listeners 7 Cups therapists offer therapy services that are convenient and affordable.You can select a therapist that best suits your need and chat with them one-on-one in a confidential setting.This isn't by any means a new technique: it's a variation of Comet, specifically XHR long polling, and/or BOSH.
Each Facebook Chat user now needs to be notified whenever one of his/her friends (a) takes an action such as sending a chat message or loads a Facebook page (if tracking idleness via a last-active timestamp) or (b) transitions between idleness states (if representing idleness as a state machine with states like "idle-for-1-minute", "idle-for-2-minutes", "idle-for-5-minutes", "idle-for-10-minutes", etc.).Note that approach (a) changes the sending a chat message / loading a Facebook page from a one-to-one communication into a multicast to all online friends, while approach (b) ensures that users who are neither chatting nor browsing Facebook are nonetheless generating server load.Another challenge is ensuring the timely delivery of the messages themselves.Take your first step now Online therapy is mental health counseling provided via the Internet. We can talk everything that we can't talk to people around us. This has helped me get better and the people here could easily relate to your problems. If you need to get something out, but can't talk to your friends/family & don't want to see a therapist 7 cups is do you. Sometimes it is called e-therapy, distance therapy, telehealth, or Internet therapy. I really love this app and have better feeling after talk about my problems to someone in this app.