CODEWITHSUNDEEP
sessionchat
Michael Jones
Michael Jones

Reputation: 2282

How do live sessions work (with multiple users)?

This has been on my mind for a while now, and I guess I am asking it now. My question is how do live sessions work? For instance, a live chat session, or the live multi-user updater on JSfiddle.net. How do both items update instantly? In the case of the live chat, is it updating from AJAX to the server every second?

Sorry if my question is misunderstood, but my question is simply, how do live sessions work with multiple users?

EDIT

How does Stack Overflow do it? Every time something happens I get a notification, is that updating to the database every second to see if something happens, or is there a better (more efficient) way of going about doing this?

Upvotes: 0

Views: 92

Answers (1)

Glubus
Glubus

Reputation: 2855

There is a couple of ways of doing it.

The most common way people are nowadays doing it is through websockets. You can just google that term and learn about it. Basically the webserver notifies you through a socket whenever it decides to.

Another way is polling. People used to do it like this back in the day. Polling is pretty much the dumb way: constantly (or every other second or so) sending an ajax request to the webserver asking if there is any new content.

Another interesting way is sending a get request that stays open for a certain amount of time, even after it gets a response. It sort of functions like a stream that you opened to a file or connection, it stays open untill you close it (or untill some other condition). I'm not too familiar with this method, but I know Google Drive uses it for it's multi-user file editing. Just open two sessions to the same Google Drive document and inspect the page. You'll see in the console that every time you type a block of text it'll send a post, and you'll have at least 1 get request pending at all times. At one point it'll close, and right away a new one starts.

So in short: Websockets, Polling, and whatever you call that last method.

Upvotes: 1

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