when the client server submit a request in the website, 
it triggers a python program in that website's server
that python program scrap data in the Internet, or do its other job.
and return the scrapped data to the user.
thanks
You need to write handler/controller functions to handle each request from the client (the view). The routers will route each request to a specific controller which invoke the code i.e. query the database (via the Model) and return data with the response to the client via that controller. Read more on MVC and frameworks like Flask/Django for more info.
how to trigger a python module in a linux website server when client submit data through website