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Chat server and client Implementation

I want to Implement a Chat Server and Client using java like gTalk, what Type of connection should i work on(XAMPP or Socket Connection), please guide me, i want to implement this for my final sem project.It will be a kind of Instant Messaging like gTalk and skype.
Please give me some idea/outlines or links where i can read some stuff, so that i can study some and start implementing those.
try {
Socket skt = new Socket("localhost", 1234);
BufferedReader in = new BufferedReader(new
InputStreamReader(skt.getInputStream()));
System.out.print("Received string: '");
while (!in.ready()) {}
System.out.println(in.readLine()); // Read one line and output it
System.out.print("'\n");
in.close();
}
catch(Exception e) {
System.out.print("Whoops! It didn't work!\n");
}
Thanks

XAMPP is mostly a package of software mainly Apache webserver, MySQL, Perl and PHP.
Since you want to code in java, the chat server would be based on Socket Programming.
As per the code snippet you have posted is a simple java server, which can listen to request and print on screen what's been send to it.
On doing some google search found a simple step by step explanation of creating chat application in java.
http://pirate.shu.edu/~wachsmut/Teaching/CSAS2214/Virtual/Lectures/chat-client-server.html

Why my chat application that does not work behind a router?

I developed a chat application Java/Socket(TCP), it works perfectly on my local network,however when i put it behind a router it does not work...
I have already tested the open ports on my router at:
http://www.yougetsignal.com/tools/open-ports/
the result is as follows
80 (HTTP)is open
21 (FTP)is open
22 (SSH)22 is open
23 (TELNET)is open
25 (SMTP)25 is open
.
.
.
I started my server with this list of ports(java -jar server.jar 23) :
int port=Integer.parseInt(args[0]);
ServerSocket serverSocket = null;
serverSocket = new ServerSocket(port);
System.out.println("server started at " + port);
Socket clientSocket = null ;
// repeatedly wait for connections, and process
while (true) {
try {
clientSocket = serverSocket.accept();
} catch (IOException ex) {
System.out.Println("error");
}
System.err.println("new client connected!");
in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream())),true);
String s;
while ((s = in.readLine()) != null) {
out.println("from server: "+s);
}
// colse all
out.close();
in.close();
clientSocket.close();
then Then with a simple client I tried to connect => anything received....
where does the problem? so how Skype,Msn and others chat application works fine?
there is a solution to do that ?
PS:I put a simple code(echo server) that represents my real server so you understand my code quickly :).
My regards .

This is just a guess, did you go into your router's configuration utility and set it up to proxy (usually called port forwarding) telnet requests to the client? Your router may be listening on 23, but unless you're running the chat client on the router's firmware, I doubt it knows what to do with that traffic. Maybe I misunderstood your question though.

Just having a server running behind a router is not enough for an outside client to establish a connection. Whatever port the server is listening on, the router needs to have a Port Forwarding rule configured on it that forwards inbound traffic for that port to the machine the server is running on. The client then needs to connect to the port on the router's public IP so the router can then forward that traffic to the server.

Sockets in Java...?

I need to build an application which can receive data from over a network and use this data to do some unrelevant things with.
Here's a piece of code to make clear what I'm doing.
On the server side:
static Socket client = null;
static ServerSocket ss = null;
if (ss != null) {
ss.close();
}
ss = new ServerSocket(5513);
isrunning = true;
System.out.println("Waiting for client...");
client = ss.accept();
System.out.println("Client accepted.");
BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
And the client side:
Socket client = null;
PrintWriter out = null;
try {
client = new Socket("hostname", 5513);
out = new PrintWriter(client.getOutputStream(), true);
}
Please note that this is just a piece of the code. There are no errors in the code.
After running the server-sided piece of code, it correctly waits for the client to connect.
Now here comes the problem. As soon as I try to connect from the client side, I'm getting a "connection refused"-error.
HOWEVER, I found something on the internet whoch told me to try telnetting from the client side. For example, let the server-sided IP be 192.168.1.1. So, after using this command:
telnet 192.168.1.1 5513
I actually get a connection with the server. The command will launch an empty screen, and everything I manually type in the command line will be sent to the server-side after pressing enter (checked with debugging).
So, I can manually connect to the server-side and send some data, but my code refuses to connect.
Anyone who knows what I am doing wrong?

Is this the code you're actually using?
client = new Socket("hostname", 5513);
Try changing it to:
client = new Socket("192.168.1.1", 5513);

client = new Socket("hostname", 5513);
Hostname needs to represent the IP Address you're connecting to. If you're trying to connect to yourself, it would be "localhost"
Also, the server is not listening for the client AT ALL TIMES, there must be a while loop so the server listens and accepts connections.
while (true) {
client = ss.accept();
out = new PrintWriter(client.getOutputStream(), true);
//You should probably assign it to a seperate thread to handle stuff for this client
}
And I should explain on why you're getting that particular error. When something says that the connection is refused, it usually means that the IP Address you want to connect to knows your sending a connection and is blocking it because it was not listening for that connection. Basically, when the server closed, you stopped listening for the client, so anything that came in on that port would be blocked. Of course, the other case could be that Java was blocked on your firewall and an exception should be made for it. Although this is rarely the case if what you're trying to accomplish is over a LAN.

You're not actually using "hostname" in your Socket object in the client are you?
It should the 192.168.1.1.

Are you on Windows? and If so have you added java.exe and javaw.exe to Firewall with inbound and outbound enabled? and have you added a rule for 5513 to your Firewall?
If yes Windows but no Firewall settings, that's your answer, open up your Firewall.

Android check if remote server is online

I am new to Android programming and I have been facing problems that didn't exist in native Java. When I run this code in my computer, it runs correctly. But, when I run it in my device.I get nothing, I even tried to post the message to UI and there's no logcat for this. I am not sure what is wrong.
try{
Socket socket = new Socket(serverAddr, SERVER_PORT);
Log.i("TAG","Socket connected");
}catch(IOException e){
Log.i("TAG","Socket not connected");
}
Update 1: I just changed the code..nothing much and realized that after 2 minutes or so it does what it was supposed to do?? Is is anything to do with keep alive flags? Or is there anyway that I can run the code just for a second or two and stop it. Please understand that the code below the socket creation line executes only after 2 minutes if the server is dead. Here below is my code:
try{
InetAddress serverAddr = InetAddress.getByName(serverIP);
//Line below executes with no delay
postToUI("Trying to connect to standalone server" + "\n\n");
socket = new Socket(serverAddr, SERVER_PORT);
//Line below executes after 2 minutes
postToUI("Successfully connected to standalone server" + "\n\n");
}catch(ConnectException e){
postToUI("Socket not connected");
}catch(IOException e){
postToUI("Socket not connected");
}

I have done very few Andrioid development so don't bite me smiley.
Possible reasons why the host might not communicate with the client
Host has firewall which might be closing the connection (unlikely)
Host might have unexpectly shutdown e.g power failure (unlikely)
Host might not properly port forwared (possibly)
Your andriod app doesn't have the proper manifest that allows the use of sockets.
Your andrioid device you are testing on might have its internet disabled which can enabled easily.
Host's address could have changed if it is dynamic.
For logcat, I think that logcat only displays log messages for the main thread. But I am unsure.

Java Socket Returns True

I hope you can help. Im fairly new to progamming and Im playing around with java Sockets.
The problem is the code below. for some reason commSocket = new Socket(hostName, portNumber); is returning true even when it has not connected with the server (server not implemented yet!). Any ideas regarding this situation?
For hostName Im passing my local machine IP and for port a manually selected port.
public void networkConnect(String hostName, int portNumber){
try {
networkConnected = false;
netMessage = "Attempting Connection";
NetworkMessage networkMessage = new NetworkMessage(networkConnected, netMessage);
commSocket = new Socket(hostName, portNumber);
// this returns true!!
System.out.println(commSocket.isConnected());
networkConnected = true;
netMessage = "Connected: ";
System.out.println("hellooo");
} catch (UnknownHostException e){
System.out.println(e.getMessage());
} catch (IOException e){
System.out.println(e.getMessage());
}
}
Many thanks.
EDIT: new Socket(.., ..); is blocking isnt it? i thought in that case if that was processed without exceptions then we have a true connection?
EDIT: I played around with anti virus and now it is working!

Had that exact same situation a few days ago on a corporate computer, and searched for it for hours.
Check your antivirus, some antivirus (like E*** N**32) use live TCP scanning that make a connection succeed even if nothing is listening on the target port but will reset it later when you try to read/write from the socket.
Add this to your code:
commSocket.getOutputStream().write(0);
commSocket.getInputStream().read();
If you get a SocketException now, you should really consider to change your antivirus.
Alternatively, set a breakpoint in your application right after creating the socket, and then use netstat -ano (on Windows) to check which process id is associated with the other endpoint of your socket (which should be on your machine if you connect to localhost).
I would suggest you to disable your antivirus, but in some cases even that does not help to unload their broken live TCP scanning driver...

The Socket constructor connects right away and will throw an IOException if it doesn't succeed. So apparently you have connected successfully to a server (this could be one you didn't make yourself).