UDP Date Time Client/Server

By: Saurabh Nandu - Monday, August 20, 2001 Add Comment

<div align="center"> <table width="90%" class="outline"> <tr> <td width="50%" class="outline">Download</td> <td width="50%" class="outline">SDK</td> </tr> <tr> <td width="50%" class="outline"> <a class="wbox" href="../../file/udpdatetime.zip">udpdatetime.zip</a> (8kb)</td> <td width="50%" class="outline">Beta2</td> </tr> </table> </div> Introduction There have been a lot of requests lately to create a networking client/server example that uses the UDP protocol for data transfer. So finally I have put together an example for you people. Making nothing very fancy this is a simple client/server example, where multiple clients can connect to the server and request the current Date and Time. The multi-threaded server waits for each client and responds to them with the current date and time. UDP Protocol As many of you might be knowing that the UDP protocol is very different from the TCP protocol. In the TCP protocol the server and the client have a flowing constant connection between them and they communicate in the form for byte streams. The TCP protocol is a bit more robust and guarantees that your message will be delivered to the other end. UDP protocol is different from this, here there is no connection between the two endpoints and the communication takes place in the form of packets of data called Datagram. Also UDP does not guarantee the delivery of your message to the endpoint (so think carefully before you use this protocol). Since there is no connection between the two end points, its very difficult for the server to know from where the Datagram came,  hence you have to explicitly tell the server the address of the client so that it can send its response at the client mentioned address (IP Address and Port Number). Screen Shots <table width="100%" class="outline"> <tr> <td width="50%" class="outline" align="center">UDP Date Time Server</td> <td width="50%" class="outline" align="center">UDP Date Time Client</td> </tr> <tr> <td width="50%" class="outline" align="center"> <img border="0" src="../../img/udpdatetimeserver.gif" width="300" height="300"></td> <td width="50%" class="outline" align="center"> <img border="0" src="../../img/udpdatetimeclient.gif" width="300" height="300"></td> </tr> </table> Code 1) udpServer.cs - The UDP Date Time Server<table width="100%" class="code"> <tr> <td width="100%"><pre>using System; using System.Net; using System.Net.Sockets; using System.Threading; using System.Windows.Forms; using System.ComponentModel; namespace MasterCSharp.WebSite.Saurabh.Networking { public class UdpDateTimeServer:Form { private UdpClient server; private IPEndPoint receivePoint; private int port = 6767; //Port for the Server to use private int ip = 127001;//IP Address 127.0.0.1 private TextBox logBox; [STAThread] public static void Main() { Application.Run(new UdpDateTimeServer()); } public override void Dispose() { base.Dispose(); } //Method called when the Windows Form is Closed public void UdpDateTimeServer_Closed(object sender, EventArgs e) { //Close the Socket - Never forget this or your //Server will remain in memory even if the //Application is terminated server.Close(); } //Constructor public UdpDateTimeServer() { //TextBox settings logBox = new TextBox(); logBox.Multiline = true; logBox.ScrollBars = ScrollBars.Vertical; logBox.ReadOnly=true; logBox.Dock = DockStyle.Fill; this.Controls.Add(logBox); this.Text ="Udp Date/Time Server"; //Wire-up the EventHandler this.Closed+=new System.EventHandler(UdpDateTimeServer_Closed); //Create the UdpClient server = new UdpClient(port); //Define a Receive point receivePoint = new IPEndPoint(new IPAddress(ip),port); //Declare a Thread Thread startServer = new Thread(new ThreadStart(start_server)); //Start the Thread startServer.Start(); } public void start_server() { logBox.Text+="Server Started \r\n"; //Infinite loop while(true) { //Receive DataGram byte[] recData = server.Receive(ref receivePoint); logBox.Text+="Packet Received!!\r\n"; System.Text.ASCIIEncoding encode = new System.Text.ASCIIEncoding(); //Split it up string[] temp = encode.GetString(recData).Split(new Char[] {'@'}); logBox.Text+="From :"+temp[0]; logBox.Text+="\r\nPort :"+temp[1]; logBox.Text+="\r\nContent :"+temp[2]; //Re-send the DataGram byte[] sendData =encode.GetBytes(System.DateTime.Now.ToString()); logBox.Text+="\r\nSending current Date Time...\r\n"; //We use the IP and Port sent by the user to send the DataGram back server.Send(sendData,sendData.Length,temp[0],Int32.Parse(temp[1])); } } } }</pre></td> </tr> </table>  2) udpClient.cs - The UDP Date Time Client<table border="0" style="border-collapse: collapse" bordercolor="#111111" width="100%" class="code"> <tr> <td width="100%"><pre>using System; using System.Net; using System.Net.Sockets; using System.Threading; using System.Windows.Forms; namespace MasterCSharp.WebSite.Saurabh.Networking { public class UdpDateTimeClient:Form { private UdpClient client; private IPEndPoint receivePoint; private int port = 6060; //Port for the Client to use private int ip = 127001;//IP Address 127.0.0.1 private TextBox logBox; [STAThread] public static void Main() { Application.Run(new UdpDateTimeClient()); } public UdpDateTimeClient() { //TextBox Properties logBox = new TextBox(); logBox.Multiline = true; logBox.ScrollBars = ScrollBars.Vertical; logBox.ReadOnly=true; logBox.Dock = DockStyle.Fill; this.Controls.Add(logBox); this.Text ="Udp Date/Time Client"; //Create the UdpClient client = new UdpClient(port); receivePoint = new IPEndPoint(new IPAddress(ip),port); Thread startClient = new Thread(new ThreadStart(start_client)); //Start the Thread startClient.Start(); } public override void Dispose() { base.Dispose(); } public void start_client() { logBox.Text+="Connecting to Server\r\n"; //Loop Flag bool continueLoop =true; while(continueLoop) { //Send DataGram //Format: Hostname@Post@Message System.Text.ASCIIEncoding encode = new System.Text.ASCIIEncoding(); string sendString="localhost@"+port.ToString()+"@Send Date Time"; byte[] sendData =encode.GetBytes(sendString); logBox.Text+="\r\nRetriving current Date Time..."; //Send to Server client.Send(sendData,sendData.Length,"localhost",6767); //Receive DataGram from Server byte[] recData = client.Receive(ref receivePoint); logBox.Text+="Packet Received!!\r\n"; logBox.Text+="DateTime :"+encode.GetString(recData); //Close Connection client.Close(); logBox.Text+="\r\nConnection Closed!!" ; //End Loop continueLoop=false; } } } }</pre></td> </tr> </table> Conclusion Programming using UDP is a bit different then programming using TCP, but then there are scenario's where you just don't care if the data has been received or not; This is where UDP comes into picture. Another notable gain is that since a constant connection is not maintained a lot of bandwidth and overhead is saved!

UDP Date Time Client/Server

Comments