Blocking client and NIO server (Write back to the client issue)

Hi everybody,

I have to develop a NIO server which can handle hundreds J2ME clients.
The clients has no NIO capabilities and use blocking reading/writing
methods.

I have no trouble to send msg from the client to the server
registering OP_READ :

Client :

OutputStream os = s.getOutputStream();
Writer writer = new OutputStreamWriter(os, "US-ASCII");
out = new PrintWriter(writer, true);
out.println("msg");

My problem is to write back data to the client from the server after
the "msg" receiving :

int numRead = socketChannel.read(this.readBuffer);

if (numRead == -1) {

   sk.channel().close();

}
else {

   this.output = msgProcessing.process(this.readBuffer);
   Socket socketClient = socketChannel.socket();

   // Get the input/output stream.
   OutputStream os = socketClient.getOutputStream();

   Writer writer = new OutputStreamWriter(os, "US-ASCII");
   PrintWriter out = new PrintWriter(writer, true);

   out.println(this.output);
   out.close();
}

this.readBuffer is OK and the output is fine too. When I try to send
the output, I get an Illegal Blocking mode exception. I tried to
configure the channel with the blocking mode at true or false but
apparently it doesn't matter in this case.

At the beginning, I also tried to write back information using the
ByteBuffer class instead of the output stream but nothing happens
either. though I didn't have Illegal Blocking mode exception but the
message never arrives to the client (it stays blocked on the reading
method).

On the client side, for reading data from the server, I did that :

InputStream is = s.getInputStream();
dis = new DataInputStream(is);
....
// Send the data to the server. (the ouput stream stuff)
// Wait for the output from the server.
....
dis.readUTF());

and

InputStream is = s.getInputStream();
in = new BufferedReader(new InputStreamReader(is));
....
// Send the data to the server. (the ouput stream stuff)
// Wait for the output from the server.
....
in.readLine();

These both techniques doesn't work for me. I'm a little stuck here so
If you have some information, I'd really appreciate ;)

Thank you, bye !