class BlockingIoExample {

    /**
     * Listing 1.1 Blocking I/O example
     * */
    public void serve(int portNumber) throws IOException {<FILL_FUNCTION_BODY>}

    private String processRequest(String request){
        return "Processed";
    }
}

        ServerSocket serverSocket = new ServerSocket(portNumber);
        Socket clientSocket = serverSocket.accept();
        BufferedReader in = new BufferedReader(
                new InputStreamReader(clientSocket.getInputStream()));
        PrintWriter out =
                new PrintWriter(clientSocket.getOutputStream(), true);
        String request, response;
        while ((request = in.readLine()) != null) {
            if ("Done".equals(request)) {
                break;
            }
            response = processRequest(request);
            out.println(response);
        }
    
<no_super_class>