Dash to send two requests in parallel to the backen

Hi,

My dash app is just a front for a restful API. The backend analyses data. The data is stored in another restful api. Data is huge. The backend stores some parameters. Requesting the parameters is fast, instantaneous. But requesting data over long periods takes 10 seconds.

I have a dropdown to select a store to analyse. When I select, it sends a request to the backend to retrieve the parameters. The backend instantiates the store, with all its available tools of data fetching and analysis, then stores it in a cache, sends the parameters to the backend, with an id to the store instance.

I have a button to request the data for that store. But I would like the first callback (from the dropdown) to start a process to retrieve the data through another request and store it in the front server in a dcc.Store when the request is done. And in the meantime, the user can do some other stuff.

How can I preload that data without disturbing the user?