Working with a remote web service. How to do it right?

Question

PHP

Good afternoon!
Given: there is a service with data that can issue data through its API. The data is not static .
Challenge: We're building a third-party app that should show different collections to the user. Collections are displayed and updated in real time.
Do I understand correctly that in such a scheme we need to have a backend written in, say, PHP. And the user interface is written in JS.
Accordingly, the user chooses what he wants to receive, JS makes a request to our backend, the backend establishes an authorized connection to the data server and issues them to the client.

Questions: we will not "get" if we make a backend in PHP? There will be no problems with the scheme that I gave? With the requirement to support the connection.
Perhaps there are some errors in the diagram?
Thank you.

Answer 1

If everything is really as you described, then you will get there - you better get node.js here

Answer 2

In general, there is usually a limit on the number of requests per second, minute, day. I have not heard about the limit on the number of connections. So I think a permanent connection is not needed here.
Since there is a limit, the data received from api should be stored on your server. So that when you make repeated requests, do not ask the api for the same thing.