fastcgi protocol

[Sad Clouds]

Hi, I'm trying to understand fastcgi protocol. I've been studying fastcgi 
specification:

http://www.fastcgi.com/drupal/node/6?q=node/22

However I'm still unsure about some of the details. I would really appreciate 
if some of the developers could answer my questions.

1. Fastcgi roles - Responder, Authorizer and Filter. I think Responder is 
supported by most web frameworks like php, perl, etc. Are there any frameworks 
that support Authorizer and Filter? How useful are these roles? How does a web 
server map different roles to fastcgi applications? Can a single fastcgi 
application support all 3 roles over a single TCP connections?

2. Multiplexing request sessions over a single TCP connection. A request 
session consists of one of more fastcgi records, that have the same request 
ID. Is this at all supported by nginx or another web frameworks?

Thanks very much