I just don't get it: I just use a normal SPDY server (node-spdy), I haven't defined any special headers like Content-Encoding
or such things and I don't compress my contents by hand.
My Question: When I want to compress my contents (not just the headers), do I have to compress everything on my own by hand? Or does SPDY gzip my contents automatically?
Yes, SPDY does not compress the payload data, just the headers. You have to compress the payload yourself.
See https://groups.google.com/d/topic/spdy-dev/HXkhL6TASN4/discussion for why SPDY data compression was removed.