Second, you should not be using the single thread model anymore. It has been depreciated. (And in my opinion, was never very useful anyway - although some notable people in this forum usually disagree with me )
Lastly, the previous poster was correct. You can use the RequestDispatcher to forward the request onto another servler, or temporarily hand off control to another servlet via include.
“Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning.” - Rich Cook