Local processing return values from fastcgi_pass

[itpp2012]

For example I have one fastcgi_pass location block and I want to process the
return values of a request to use in a second fastcgi_pass, is this possible
?

location ... {
...
fastcgi_pass server1;
# server1 returns some values
# process these values and call another fastcgi_pass server
if (!$valuechecked) { return 404; }
fastcgi_pass server2;
}

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,252200,252200#msg-252200