Backend Protocol Examples?

I tried to do execute the following, but each time the program hangs
waiting on the ReceiveString.  Also, the new postgres process started
to handle the query has a really high CPU % as reported by top.

I'd love to see simple examples of conversing with the backend.  Also,
is there a nice summary of the protocol that offers more nitty-gritty
than the standard FE/BE discussion in the 7.4 docs?

Thanks!

        synchronized( pg_stream ) {
            try {
                pg_stream.SendChar('Q');
                pg_stream.Send( c.getEncoding().encode( "BEGIN" ));
                pg_stream.SendChar(0);
                pg_stream.flush();

                System.out.println("step1");
                str = pg_stream.ReceiveString( c.getEncoding() );
                System.out.println("step2");