In the earlier chapters, we built an application that mixed the notion of a chat and a forum. If we use it, we'll face some problems for sure; indeed, when we post a new message or image, the other users that are connected won't be notified unless they refresh their whole page. This kind of workflow is a pain in terms of performance and user experience. As it requires several users' actions, and because all data has to be provided by the server (which will give the same stuff again and again); think about big images that are loaded each time the application is refreshed. All of this tells us that such a workflow is not optimal at all. How are we going to tackle this? First we will use the ancestral polling system.
Polling is a system asking the server (or a bunch of services) the same resources repeatedly, and, normally, at a high rate (the higher it is, the better user experience you should have). So, it's trivial that it'll consume a lot of power, and often wasted because...