Exam success but probably a design failure

Hi,
I've successfully passed an exam, but I've scored only 7/40 on Network Server (and a lot better in other categories fortunately :-)). I'd like to share my design with you so maybe somebody can give me a hint about what is wrong with my networking.

In implementation I went for sockets and my server provided a data access interface (DBMain) over the network. And here is an excerption from my choices.txt about networking:

----

The *NetworkServer* class implements a network server functionality. It follows the pattern:

while (true) {
accept a connection ;
create a thread to deal with the client ;
end while

The *ServerWorker* class represents a thread that is spawned to serve a client. This thread uniquely identifies the client on the server.
The *WorkerManager* class manages creation of the threads, keeps the list of active threads and registers a callback in each thread. That callback is called when thread is about to die, to perform cleanup.
There is also the *AppSocket* class which uses a Socket to talk the application specific protocol (see below).
And finally there is the *NetworkProxy* class (to be used on the client side) which implements the InvocationHandler interface and is capable of transforming a method call into a corresponding network message. On the server side the *ServerWorker* reads the message and uses reflection to call an appropriate method on the target object (which is a database object).

The point is that *NetworkProxy* is capable of converting *any* method call into a network message/command and that *ServerWorker* is capable of calling the right method on the server side, which is very handy.
...

3.1 Protocol
A typical client server conversation in my application looks like this:

Server Client
| |
listen |
| connect
OkMessage -> | #handshake
| <- CommandMessage #request
ObjectMessage -> | #response
... <- CommandMessage #request
... ... ...
| disconnect
| |

There is also ErrorMessage class for comunicating business exceptions.

----

From the time perspective I think that this design is an overkill and too generic. The NetworkProxy class can act as a proxy for any interface (a DBMain in my case), it just marshalls any method call over the network. On the server-side a reflection is used (given the information send over the network) to call an appropriate method on a business object (DBMain implementation in my case). This looks a bit like a self-made RMI, but it was fun to design and implement it.

Is really overdesigning enough reason to substract 33 points?

Tomek

I'am sorry the protocol description ASCII art didn't get through the forum formatting, maybe this time:

...
3.1 Protocol
A typical client server conversation in my application looks like this: