Display Number of Online Users in ASP.NET

All of us have seen many Websites displaying the number of online users. In this Article, We will learn how to Display Number of Online Users in ASP.NET Web Application / WebSite.

Let's Begin:
1) Go to File -> New -> Website -> Select ASP.NET Empty Web Site
2) Right Click on Website Project (in Solution Explorer) -> Add -> Click on Add New Item
3) Select Global Application Class (Global.asax) -> Click on Add Button.

You will see various events of Global.asax file like Application_Start, Application_End etc. Application_Start event called once when application starts. Session_Start event called every time when a new session is start. Session_End event called when a user session ends. In Application_Start Event, We will initialize our Application state variable.

Global.asax Code:

<%@ Application Language="C#" %> <script runat="server">     void Application_Start(object sender, EventArgs e)     {         // Code that runs on application startup         Application["TotalOnlineUsers"] = 0;     }         void Application_End(object sender, EventArgs e)     {         //  Code that runs on application shutdown     }             void Application_Error(object sender, EventArgs e)     {         // Code that runs when an unhandled error occurs     }     void Session_Start(object sender, EventArgs e)     {         // Code that runs when a new session is started         Application.Lock();         Application["TotalOnlineUsers"] = (int)Application["TotalOnlineUsers"] + 1;         Application.UnLock();     }     void Session_End(object sender, EventArgs e)     {         // Code that runs when a session ends.         // Note: The Session_End event is raised only when the sessionstate mode         // is set to InProc in the Web.config file. If session mode is set to StateServer         // or SQLServer, the event is not raised.         Application.Lock();         Application["TotalOnlineUsers"] = (int)Application["TotalOnlineUsers"] - 1;         Application.UnLock();     }        </script>

In Web.config file, Add SessionState within system.web element. By Default Session uses Cookies (cookieless="false") and Default timeout period is of 20 minutes.

<system.web> <sessionState mode="InProc" cookieless="false" timeout="20"></sessionState> </system.web>

4) Add a Webform and drop a label control from the Toolbox.

Default.aspx Code:

<form id="form1" runat="server">     <div>     <p>No. of Online Users:<asp:Label ID="Label1" runat="server" Text="Label" ForeColor="#CC0000"></asp:Label></p>     </div> </form>

Default.aspx.cs:

protected void Page_Load(object sender, EventArgs e) {         Label1.Text = Application["TotalOnlineUsers"].ToString(); }

Run the Application (ctrl+ F5). For checking, copy the url and paste it in the new instance of different browser. When a visitor visit your website, a new session is started for him and Application["TotalOnlineUsers"] variable increased by 1. When user session expires than Application["TotalOnlineUsers"] variable decreased by 1.
Preview:

We can also use Cookieless session by setting cookieless property to true.

<sessionState mode="InProc" cookieless="true" timeout="20"></sessionState>

On running the application, you will see Session ID in URL which is different for all users, sessions, for the new instance of different browser. The session ID is embedded in the URL in the format shown below.

http://yourserver/(session ID here)/default.aspx

Preview:

Hope you like it. Thanks. 

[Download Source Code via Google Drive]

Video: