There's a problem, in General, that a sensible answer I in these the Internet is not found.
And so to the point, for example I want to write a notification system for the site, for example on the website there is a cherished button husky and two user(say user_1 and user_2). So, user_2 like to post user_1, user_2 id is preserved in the database under the post user_1, then I need somehow to pull user_1 and to show that he liked.
Considering how the majority of sites, is it possible in any way to send the client the info that he liked without any interaction of the client with the backend? Or it is necessary to write a demon?
I do not understand anything, thanks in advance for your help, look forward to your answers!:)
The easiest way short of polling the respondents regularly APIs for new data.
A little more complicated - Long polling is the same, but the timeout is longer (usually about 20C, the gold standard)
Another sophisticate - websocket
Even more interesting - push notifications
On the server side in any case, it is necessary to generate any events or notifications, and to store for each user you want the client to receive them. There will be a table and the queue (message broker)