Listening for TCP and UDP requests on the same port
- by user339328
I am writing a Client/Server set of programs
Depending on the operation requested by the client, I use make TCP or UDP request.
Implementing the client side is straight-forward, since I can easily open connection with any protocol and send the request to the server-side.
On the servers-side, on the other hand, I would like to listen both for UDP and TCP connections on the same port. Moreover, I like the the server to open new thread for each connection request.
I have adopted the approach explained in: link text
I have extended this code sample by creating new threads for each TCP/UDP request.
This works correctly if I use TCP only, but it fails when I attempt to make UDP bindings.
Please give me any suggestion how can I correct this.
tnx
Here is the Server Code:
public class Server {
public static void main(String args[]) {
try {
int port = 4444;
if (args.length > 0)
port = Integer.parseInt(args[0]);
SocketAddress localport = new InetSocketAddress(port);
// Create and bind a tcp channel to listen for connections on.
ServerSocketChannel tcpserver = ServerSocketChannel.open();
tcpserver.socket().bind(localport);
// Also create and bind a DatagramChannel to listen on.
DatagramChannel udpserver = DatagramChannel.open();
udpserver.socket().bind(localport);
// Specify non-blocking mode for both channels, since our
// Selector object will be doing the blocking for us.
tcpserver.configureBlocking(false);
udpserver.configureBlocking(false);
// The Selector object is what allows us to block while waiting
// for activity on either of the two channels.
Selector selector = Selector.open();
tcpserver.register(selector, SelectionKey.OP_ACCEPT);
udpserver.register(selector, SelectionKey.OP_READ);
System.out.println("Server Sterted on port: " + port + "!");
//Load Map
Utils.LoadMap("mapa");
System.out.println("Server map ... LOADED!");
// Now loop forever, processing client connections
while(true) {
try {
selector.select();
Set<SelectionKey> keys = selector.selectedKeys();
// Iterate through the Set of keys.
for (Iterator<SelectionKey> i = keys.iterator(); i.hasNext();) {
SelectionKey key = i.next();
i.remove();
Channel c = key.channel();
if (key.isAcceptable() && c == tcpserver) {
new TCPThread(tcpserver.accept().socket()).start();
} else if (key.isReadable() && c == udpserver) {
new UDPThread(udpserver.socket()).start();
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
} catch (Exception e) {
e.printStackTrace();
System.err.println(e);
System.exit(1);
}
}
}
The UDPThread code:
public class UDPThread extends Thread {
private DatagramSocket socket = null;
public UDPThread(DatagramSocket socket) {
super("UDPThread");
this.socket = socket;
}
@Override
public void run() {
byte[] buffer = new byte[2048];
try {
DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
socket.receive(packet);
String inputLine = new String(buffer);
String outputLine = Utils.processCommand(inputLine.trim());
DatagramPacket reply = new DatagramPacket(outputLine.getBytes(), outputLine.getBytes().length,
packet.getAddress(), packet.getPort());
socket.send(reply);
} catch (IOException e) {
e.printStackTrace();
}
socket.close();
}
}
I receive:
Exception in thread "UDPThread" java.nio.channels.IllegalBlockingModeException
at sun.nio.ch.DatagramSocketAdaptor.receive(Unknown Source)
at server.UDPThread.run(UDPThread.java:25)
10x
