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Alexander Nortung
Alexander Nortung
6,930 Points

Server sent events

Hello recently i have been building an application for My website that uses Ajax to run a script that will update a part of the page, the problem is i believe Ajax polling takes a lot for the server and network to use when i am updating it every 2 seconds, imagine if there was 1000 people requesting the same thing every 2 seconds, that's not what i want.

My question is: how can i make it run the script for example whenever the database is updated or a new row was added? I would like to make something similar to a chat. I have read about server sent events, long polling and websockets, but I don't know what to use or how to use it with the current courses in the Treehouse library.

2 Answers

David Bath
David Bath
25,940 Points

You might enjoy this (non-Treehouse) tutorial: http://socket.io/get-started/chat/

There are several ways to get updates pushed from the server instead of frequently polling from the client. Long polling is where you send a request just as you do now, but instead of getting a response and requesting again in 2 seconds, the server waits to respond until there is new data to send. You can read more about it here: https://www.pubnub.com/blog/2014-12-01-http-long-polling/.

For a more real time connection there are technologies like WebSockets (https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API) and server-sent events (https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events). I haven't used either of them, but I know codepen.io uses faye-websockets (https://www.npmjs.com/package/faye-websocket) for their Collab Mode and they have more than half a million users.

For a more exhaustive overview of all the options, check out the Wikipedia page on push technologies (https://en.wikipedia.org/wiki/Push_technology).

Hope this helps.