Tomcat 5.x thread model

[COURTAULT Francois]

Hello,
 
I want to know what is the model used by Tomcat between the socket and
the thread ?
 
Is it one socket - one thread ? For example the communication between
one entity and a Tomcat instance uses HTTP 1.1 is establish by invoking
servlet1, if the entity invokes again servlet1 (without any
communication close): is it the same thread which processes the servlet
? 
 
Is it configurable ?
 
Regards.