This is an example server using protocol buffers inside of a rest endpoint in Lisp. We use the cl-protobufs lisp protocol buffer implemenation and the Hunchentoot lisp webserver.
The author makes no claim of optimality. Really one probably shouldn't use bare Hunchentoot but something like Caveman. Also, some work should be done to have better protocol buffer support in the client. This is left as an exercise to the reader.