HOW TO MAKE A CHAT APPLICATION

This project shows you how to make a chat application step by step in Microsoft Visual C#. This project uses UDP (User Datagram Protocol) Socket connection between two chat applications. This chat application will be worked within the same network or inter network. However, in this project, I shall be focusing on how to communicate asynchronously with two chat applications. Asynchronous Communication system is a way of communication where both side can communicate simultaneously with each other. For example, a telephone call is an example of asynchronous communication system. I am going to show you step by step skipping no step. Step 1: First make a project, go to Microsoft Visual C# then create a project like following: Image Step 2: Design the Chat Application form with textbox, label, button and group boxes as follows. Image Give the form objects name as follows: Your IP textbox name = textLocalIp, Your Port textbox name = textLocalPort, Friend’s IP textbox name = textFriendsIp Friend’s Port textbox name = textFriendsPort Listbox Message name = listMessage, Textbox for Message sending name = textMessage, Start Button name = buttonStart, Send Button name = buttonSend Step 3: Add 2 namespaces in the project. 1 2 using System.Net; using System.Net.Sockets; Step 4 : Add the following code under form load, double click on the form then write the following code. 1 2 3 4 5 6 7 // set up socket sck = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); sck.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress,true); // get own IP textLocalIp.Text = GetLocalIP(); textFriendsIp.Text = GetLocalIP(); Then add a method GetLocalIP() as follows. This method will return Local IP address to the text boxes. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 // Return your own IP private string GetLocalIP() { IPHostEntry host; host = Dns.GetHostEntry(Dns.GetHostName()); foreach (IPAddress ip in host.AddressList) { if (ip.AddressFamily == AddressFamily.InterNetwork) { return ip.ToString(); } } return "127.0.0.1"; } Step 5: Add this following code under Start Button click event. try { // binding socket epLocal = new IPEndPoint(IPAddress.Parse(textLocalIp.Text), Convert.ToInt32(textLocalPort.Text)); sck.Bind(epLocal); // connect to remote IP and port epRemote = new IPEndPoint(IPAddress.Parse(textFriendsIp.Text), Convert.ToInt32(textFriendsPort.Text)); sck.Connect(epRemote); // starts to listen to an specific port buffer = new byte[1500]; sck.BeginReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref epRemote, new AsyncCallback(MessageCallBack), buffer); // release button to send message buttonSend.Enabled =true; buttonStart.Text = "Connected"; buttonStart.Enabled =false; textMessage.Focus(); } catch (Exception ex) { MessageBox.Show(ex.ToString()); } Now, you need to add a callback function MessageCallBack. Just add the following code. try { int size = sck.EndReceiveFrom(aResult, ref epRemote); // check if theres actually information if (size > 0) { // used to help us on getting the data byte[] receivedData = new byte[1464]; // getting the message data receivedData = (byte[])aResult.AsyncState; // converts message data byte array to string ASCIIEncoding eEncoding = new ASCIIEncoding(); string receivedMessage = eEncoding.GetString(receivedData); // adding Message to the listbox listMessage.Items.Add("Friend: " + receivedMessage); } // starts to listen the socket again buffer = new byte[1500]; sck.BeginReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref epRemote, new AsyncCallback(MessageCallBack), buffer); } catch (Exception exp) { MessageBox.Show(exp.ToString()); } Step 6: In this step you need to add the following code under send button click event. try { // converts from string to byte[] System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding(); byte[] msg = new byte[1500]; msg = enc.GetBytes(textMessage.Text); // sending the message sck.Send(msg); // add to listbox listMessage.Items.Add("You: " + textMessage.Text); // clear txtMessage textMessage.Clear(); } catch (Exception ex) { MessageBox.Show(ex.ToString()); } Step 7: Now build the project by clicking Build menu then Build Solution sub menu. And now go to the project folder and go inside the project folder to bin then bin debug. In the debug folder you will the ChatApps.exe file. Open two instance for testing purpose in your computer then give different Port number as you are listening in the same IP. Then connect both Application and start sending message. Hope you will enjoy this project. If you want to chat with your friends or colleague in the LAN or Same network then give them a copy of ChattApps.exe and now you will be able to chat from different Computer.