why cookie is set in response but session in request?

Question

I know how session and cookies work. I am doing an online course on django where a function for setting language preference in session and cookie is written in views.py. I do not understand why cookie is set on response but session on request. The instructor mentioned it works the same in PHP or any other web framework.

but he did not explain why? can some one explain why?

Here is the function:

def language(request,language=“en-us”):
    response=HttpResonse(“setting language to %s” %language)

    response.set_cookie(‘lang’,language)
    request.session[‘lang’]=language

    return response

Answer 1

I will talk about Java but it shall be similar in django. Session attributes are accesible in servlets and jsp in similar way like request parameters. You can look at it like server side stored request parameters. Some frameworks like JSF even use request scope to store session variable. So basicly you can look at session as request decorator which puts value stored in web container.