Java Servlets - set or alter cookies in included servlet

Question

Given that we have two servlets A and B and servlet A includes servlet B using

request.getRequestDispatcher("/B").include(request,response);

Why can't I set or alter cookies in servlet B? I don't receive any errors but it seems like the changes on the cookies are being ignored. Can anyone explain this kind of behaviour?

Answer 1

According to RequestDispatcher.include documentation :

.....

The ServletResponse object has its path elements and parameters remain unchanged from the caller's. The included servlet cannot change the response status code or set headers ; any attempt to make a change is ignored .

.....

And since Cookies are part of the returned header (of the calling Servlet), that's why the changes are not taking effect (ignored).