I’ve used a bit of AJAX with PHP for things like submitting forms and I’ve recently started looking into websockets. I followed this tutorial to understand the basics. From what I gather, websockets keep the connection open whereas AJAX opens and closes a request.
My question is do websockets provide any advantage over AJAX if you’re just submitting forms or simple tasks like auto_complete (which there’s a jQuery plugin for anyway)? Maybe the tutorial isn’t the greatest, but it seems like there’s a heck of a lot more code involved to get websockets to work(at least with PHP) than just a simple AJAX call (or using jQuery which bundles it). I’ve read in a few places that it’s a bit quicker, but if I’m working on something that isn’t receiving tons of requests, will it really make a difference? Correct me if I’m wrong, but not all browsers support websockets either, right?
Websockets have two advantages.
they have much less overhead, which results in a better network performance
they allow the server to send data which the client hasn’t explicitely requested.
The second one is the most important advantage.
In AJAX, everything the server sends must be the response to a previous request by the client, and every request can only be answered once. But in many applications, especially multi-user applications, events happen on the server and these events must be pushed to the clients immediately. There are workarounds for that in AJAX, like delaying the answer to a request until there is something to report (long-polling), but these are quite dirty. That’s why there are Websockets. With a websocket connection, the server can send messages to the clients when it wants and as often as it wants, without having to wait for a request from the client.
But unfortunately WebSockets also have disadvantages: