I wrote a very scalable HTTP event server in C++ and I would like to make it
work with nginx. My server is on port 9001, PHP-FPM is running on port 9000.

My server is set up to return a 504 error when an event is found, and the 504
error should trigger the PHP backend. I've been trying to figure out a way to make it work with nginx and it's
something so elementary, I think I'm just being really stupid.. so I need some
help.

This is basically a short rundown of what happens. A client hits something like myhost.com/event/, and hangs until there is an
event to server, expiring after 30 seconds by default (if it expires, my server
returns a "NO EVENT" reply, which works); however, if there IS an event, my
server is set up to kick off the client, triggering a 504. Somehow I want to
catch that 504, and redirect the client to a PHP backend (with the query
intact).

This is what I have so far. I haven't worked much with nginx so bear with me...

location /event/ { proxy_pass http://localhost:9001/callback.eve; proxy_intercept_errors on; error_page 504 = @fallback; #if I straight up put backend.php here,
the POST/GET variables disappear }

location @fallback { internal; fastcgi_param SCRIPT_FILENAME $document_root/backend.php; fastcgi_param QUERY_STRING $query_string; include fastcgi_params; fastcgi_pass 127.0.0.1:9000; }

I get some really strange results with the aforementioned config.. nginx doesn't
break, I don't get an error or anything. PHP doesn't break either. All I get is
a blank page (as in, totally blank) with a 200 OK code. I'm really confused
here, and I'm almost certain there has to be an easy way of doing this

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,36944,36944#msg-36944