Set Cookie Header

[Stefan Botzenhart]

At the moment I'm testing different caching mechanisms including Rack-
Cache. I ran into the following issue: while testing around with
varnish cache I recognized that the "Set-Cookie" header is set by
rails although it's empty which is a great problem with http caches.

Then I thought to test this with rack cache and I had to realize that
there's no "Set-Cookie" header and that's great. Then I set a flash
message manually and reload the page but no "Set-Cookie" header
appeared. No I am wondering if this is correct or not. In case this
behaviour is correct: Why? I do not understand it.

Thanks for helping me!

Regards,
Stefan