Creating Point-to-Multipoint connection using Bluetooth

Question

Hi,
I have a problem with my application. It's supposed to be a part of a Bluetooth multiplayer game responsible for data exchange between devices. I created it based on the code from
[http://www.forum.nokia.com/info/sw.nokia.com/id/2b17fb6f-b9a4-4cd8-80fd-94b8251a048e/Games_Over_Bluetooth_v1_0_en.zip.html]
The part of the code responsible for detecting devices and connecting with them works just fine both on the emulator and real devices. The data exchange works perfectly on my Netbeans 6.5.1 and WTK 2.5.2 in the default emulator, but the problems arise when try to run it on SE C905, Nokia N73 and Nokia 5530 XpressMusic (it doesn't work even between any two devices).
The data exchange should look like this:
1. Send data from clients to the server -> 2. server receives the data -> 3.Server sends combined data from all clients to each client-> 4. clients receive the combnied data -> go back to 1.
The problem on the real devices is that the connection is opened but data is not exchanged. The first piece of data is sent from the client and received by the server, but after that nothing gets received.
It gets lost somewhere... The data is exchanged in DataExchange inner class
I would be very grateful for any help
Here's my code:
Client:
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.bluetooth.*;
import javax.microedition.io.*;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
* @author Zawada
public class MultiClient extends MIDlet implements CommandListener {
    private Display display;
    private Form clientForm;
    private Command exitCommand;
    private LocalDevice local_device;
    private DiscoveryAgent disc_agent;
    private String service_UUID;
    private String player_name;
    private String url;
    private StreamConnectionNotifier notifier;
    private StreamConnection con;
    private InputStream is;
    private OutputStream os;
    private boolean isConnectionActive = false;
    private String message = "5678";
    private Thread dataExchange;
    public MultiClient() {
        display = Display.getDisplay(this);
        clientForm = new Form("Bluetooth Client");
        clientForm.append("Application started\n\n");
        exitCommand = new Command("Exit", Command.EXIT, 1);
        clientForm.addCommand(exitCommand);
        clientForm.setCommandListener(this);
    public void startApp() {
        display.setCurrent(clientForm);
        try {
            setUpClient();
        } catch (IOException ex) {
            ex.printStackTrace();
    public void pauseApp() {
    public void destroyApp(boolean unconditional) {
        isConnectionActive = false;
        if (is != null & os != null & con != null) {
            try {
                // Multiplayer session is stopped: Disconnect the devices
// close input stream
                is.close();
// close output stream
                os.close();
// Close connection
                con.close();
            } catch (IOException ex) {
                ex.printStackTrace();
        notifyDestroyed();
    public void commandAction(Command c, Displayable d) {
        if (c == exitCommand) {
            destroyApp(true);
    private void setUpClient() throws IOException {
        try {
            // Obtain local device object
            local_device = LocalDevice.getLocalDevice();
// Obtain discovery agent object
            disc_agent = local_device.getDiscoveryAgent();
// Set device into limited access mode. Inquiry scan
// will listen only to LIAC.
            local_device.setDiscoverable(DiscoveryAgent.GIAC);
// Do the service search on all found devices.
// Note: don’t use this UUID in your own MIDlets.
// You have to create an own UUID for each MIDlet that you write:
            service_UUID = "F0E0D0C0B0A000908070605040302010";
// Retrieve players name
// This could be a name that user has modified and stored to
// non-volatile memory. As default (when game is first started)
// the local friendly name could be chosen.
            player_name = "Ziom";//local_device.getFriendlyName();
// Open connection, note: name is attribute ID 0x0100
            url = "btspp://localhost:" + service_UUID + ";name=" + player_name;
            notifier = (StreamConnectionNotifier) Connector.open(url);
// Wait on someone to connect (note: you can cancel this wait
// only if you call notifier.close() from another thread.
// This is important if you want to offer a UI for the user
// to cancel connections setup.)
            con = (StreamConnection) notifier.acceptAndOpen();
// open input stream
            is = con.openInputStream();
// open output stream
            os = con.openOutputStream();
            clientForm.append("Connection opened\n");
// Devices are connected now:
// Run the game / exchange data ...
            dataExchange = new DataExchange();
            dataExchange.start();
        } catch (BluetoothStateException ex) {
            ex.printStackTrace();
    private class DataExchange extends Thread {
        private byte[] sentData;
        private byte[] receivedData;
        public DataExchange() {
            isConnectionActive = true;
        public void run() {
            int j = 0;
            while (isConnectionActive == true) {
                try {
                    sentData = message.getBytes();
                    os.write(sentData);
                    System.out.println("data written: " + new String(sentData));
//                        clientForm.append("Data sent\n");
                    int lengthavai = 0;
                    //wait till having received data from the server
                    while ((lengthavai = is.available()) <= 0) {
//                        clientForm.append("Waiting for data\n");
                    receivedData = new byte[lengthavai];
                    int length = is.read(receivedData);
                    System.out.println("data read: " + new String(receivedData));
                    clientForm.append(new String(receivedData));
                } catch (IOException ex) {
                    clientForm.append("IO ex\n");
                    ex.printStackTrace();
                j++;
}

Answer 1

Server:
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Enumeration;
import java.util.Vector;
import javax.bluetooth.*;
import javax.microedition.io.Connector;
import javax.microedition.io.StreamConnection;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
* @author Zawada
public class MultiServer extends MIDlet implements CommandListener {
    private Display display;
    private Form serverForm;
    private Command exitCommand;
    private LocalDevice local_device;
    private String url;
    private StreamConnection[] con;
    private InputStream[] is;
    private OutputStream[] os;
    private String message = "1234";
    private boolean isConnectionActive = false;
    private UUID[] u;
    private int numberOfClients;
    private Thread dataExchange;
    public MultiServer() {
        display = Display.getDisplay(this);
        serverForm = new Form("Bluetooth Server");
        serverForm.append("Application started\n\n");
        exitCommand = new Command("Exit", Command.EXIT, 1);
        serverForm.addCommand(exitCommand);
        serverForm.setCommandListener(this);
    public void startApp() {
        display.setCurrent(serverForm);
        System.out.println("5678".getBytes().length);
        try {
            setUpServer();
        } catch (BluetoothStateException ex) {
            serverForm.append("BT ex\n");
            ex.printStackTrace();
        } catch (InterruptedException ex) {
            serverForm.append("Interr ex\n");
            ex.printStackTrace();
        } catch (IOException ex) {
            serverForm.append("IO ex\n");
            ex.printStackTrace();
    public void pauseApp() {
    public void destroyApp(boolean unconditional) {
        isConnectionActive = false;
// Multiplayer session is stopped: Disconnect the devices
        for (int i = 0; i < numberOfClients; i++) {
            try {
                if (is != null & os != null & con != null) {
// close input stream
                    is.close();
// close output stream
os[i].close();
// Close connection
con[i].close();
} catch (IOException ex) {
ex.printStackTrace();
notifyDestroyed();
public void commandAction(Command c, Displayable d) {
if (c == exitCommand) {
destroyApp(true);
private void setUpServer() throws BluetoothStateException, InterruptedException, IOException {
// Obtain local device object
local_device = LocalDevice.getLocalDevice();
// Obtain discovery agent object
DiscoveryAgent disc_agent = local_device.getDiscoveryAgent();
// Disable page scan and inquiry scan
local_device.setDiscoverable(DiscoveryAgent.NOT_DISCOVERABLE);
// create inquiry listener object
InquiryListener inq_listener = new InquiryListener();
synchronized (inq_listener) {
// start a limited access inquiry and install inquiry listener
disc_agent.startInquiry(DiscoveryAgent.GIAC, inq_listener);
serverForm.append("Inquiry started\n");
// Wait
inq_listener.wait();
serverForm.append("Inquiry ended\n");
// Do the service search on all found devices
u = new UUID[1];
// Note: don’t use this UUID in your own MIDlets.
// You have to create an own UUID for each MIDlet that you write:
u[0] = new UUID("F0E0D0C0B0A000908070605040302010", false);
int attrbs[] = {0x0100};
// Retrieved service record should include player
// name (service name)
Enumeration devices = inq_listener.cached_devices.elements();
serverForm.append("Number of devices found: " + inq_listener.cached_devices.size() + "\n");
ServiceListener serv_listener = new ServiceListener();
while (devices.hasMoreElements()) {
synchronized (serv_listener) {
// on each device do a service search
disc_agent.searchServices(attrbs, u, (RemoteDevice) devices.nextElement(), serv_listener);
serverForm.append("Service inquiry started\n");
// Wait
serv_listener.wait();
serverForm.append("Service inquiry ended\n");
// Now all devices which offer the requested service (game)
// can be found in the serv_listener.FoundServiceRecord list.
// This list would now be presented to the user and user can filter
// this list/ select one or more devices to connect to.
// Or in other words: remove all devices from FoundServiceRecords
// list that you don't want to connect to.
// Here we just print all the (remote) player names
numberOfClients = serv_listener.FoundServiceRecords.size();
serverForm.append("Number of clients: " + numberOfClients +"\n");
String player_name;
for (int i = 0; i < numberOfClients; i++) {
// Retrieve player name which is contained as service name
// (0x0100) in the service record
player_name = (String) ((ServiceRecord) serv_listener.FoundServiceRecords.elementAt(i)).getAttributeValue(
0x0100).getValue();
// print name
System.out.println(player_name);
// After filtering these devices will be connected:
con = new StreamConnection[numberOfClients];
is = new InputStream[numberOfClients];
os = new OutputStream[numberOfClients];
for (int i = 0; i < numberOfClients; i++) {
// Retrieve url for one device/service
url = ((ServiceRecord) serv_listener.FoundServiceRecords.elementAt(i)).getConnectionURL(ServiceRecord.AUTHENTICATE_ENCRYPT, false);
// Open connection
con[i] = (StreamConnection) Connector.open(url);
// open input stream
is[i] = con[i].openInputStream();
// open output stream
os[i] = con[i].openOutputStream();
serverForm.append("Connection " + i + " opened\n");
// Devices are connected now:
// Run the game / exchange data ...
dataExchange = new DataExchange();
dataExchange.start();