Building a simple J2ME chat client (for own J2SE-based server) Threading Qs

Question

Hi!
I am making my own simple chat / messenger service to use between a couple of friends over GPRS.
On the server side i have made a multi threaded TCP server that opens a new thread for each connecting client and stores these socket connections in a hashtable for access to send data between each thread.
So when a client logs on to the server, the server sends a printwriter message to all other clients informing them of what client connected, and the clients can put the username in its out-database. then the clients can send messages to each others using a simple, self build protocol.
All connection between clients/server happens over a simple printwriter on in/out streams.
Problem is: it works perfectly most of the time.... However, sometimes a message is mysteriously lost when transferred from the server to a client. Transfer from client to server works flawlessly. I am thinking that it might have something to do with the client side threading, or slow network transfer casuing a TCP read error.
Client structure is as following:
start-> Midlet class -> (press connect to server) -> new Client class (impl runnable) -> new thread(this) -> void run() sets up all connections and writers, waits in a while loop for messages from server and takes action according to message type. -> Button(send) uses output stream to send a message to server.
Do anyone have any suggestions on what I must consider when making a client that will simultaniously be able to listen for data from server as well as send data to server over 1 socket and slow mobile connection without causing any trouble?
More info can be provided if necessary.
Thank you!

Answer 1

Building a simple J2ME chat client (for own J2SE-based server)a. i would like to say that this is a bl00dy brilliant idea. i mean ~ its been done before but building one yourself is quite thrilling.
b. are u using java 4 or java 5. ?
sometimes a message is mysteriously lost when transferred from the server to a client. Transfer from client to server works flawlessly.are you using push registry to recieve incoming connections.
i recommend using a StreamConnectionNotifier connection instead of just a socket connection. you could send your data (xml/plain text) just like a stream (tcp ofcourse). if you want to know how to use a StreamConnectionNotifier connection, here's how
try{
// listen at local port 789
StreamConnectionNotifier notify = (StreamConnectionNotifier) Connector.open(“http://:789”);
// infinite loop to get incoming connections
for(;;)
StreamConnection stream = notify.acceptandOpen();  // return a stream connection when a connection is made
InputStrean mystream = stream.openInputStream();
while(mystream!=-1)
mystream.read();
....cheers