That's correct. In fact, at the moment Einhorn only supports TCP sockets. (That being said, I might be mistaken, but I think that Unicorn can also bind TCP sockets.)
Thank you for the follow-up. Even though Unicorn does support TCP sockets, it is irrelevant for our JRuby apps as I believe (IIRC) it won't even install under JRuby due to being written in C only, with no native-Java or pure-Ruby alternatives available. So it's not a Web server that can be used for serving JRuby apps.
Now, since you've extracted the capabilities of Unicorn out into something that isn't coupled to a Web server (and it's written in pure Ruby, so is portable), we should be able to use it as a shim between nginx for managing Trinidad (Tomcat) instances. Very much looking forward to giving it a try - thanks for your efforts!
EDIT: Whoops, guess I spoke a bit too soon. I get this error:
NotImplementedError: fork is not available on this platform
I think a typical workaround on JRuby is to use the posix-spawn or spoon gems. If I have some time this next weekend maybe I could test this a bit more and maybe formulate a patch. Example posix-spawn usage [here][1].
