How can I determine the number of users on an ASP.NET site (IIS)? And their info?

Question

Is there a way to determine the number of users that have active sessions in an ASP.NET application? I have an admin/tools page in a particular application, and I would like to display info regarding all open sessions, such as the number of sessions, and perhaps the requesting machines' addresses, or other credential information for each user.

Answer 1

The way I've seen this done in the past is adding extra code to the Session_OnStart event in the Global.asax file to store the information in a session agnostic way, e.g. a database or the HttpApplicationState object. Depending upon your needs you could also use Session_OnEnd to remove this information.

You may want to initialise and clean up some of this information using the Application_Start and Application_End events.

The administration page can then read this information and display statistics etc.

This is explained in more depth at http://msdn.microsoft.com/en-us/library/ms178594.aspx and http://msdn.microsoft.com/en-us/library/ms178581.aspx.

Answer 2

ASP.NET Performance Counters like State Server Sessions Active (The number of active user sessions) should help you out. Then you can just read and display the performance counters from your admin page..

Answer 3

In global.aspx

void Application_Start(object sender, EventArgs e)
{
    // Code that runs on application startup
    Application["OnlineUsers"] = 0;
}

void Session_Start(object sender, EventArgs e)
{
    // Code that runs when a new session is started
    Application.Lock();
    Application["OnlineUsers"] = (int)Application["OnlineUsers"] + 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["OnlineUsers"] = (int)Application["OnlineUsers"] - 1;
    Application.UnLock();
}

Note: The Application.Lock and Application.Unlock methods are used to prevent multiple threads from changing this variable at the same time.

In Web.config

Verify that the SessionState is "InProc" for this to work

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

In your .aspx file

Visitors online: <%= Application["OnlineUsers"].ToString() %>

Note: Code was originally copied from http://www.aspdotnetfaq.com/Faq/How-to-show-number-of-online-users-visitors-for-ASP-NET-website.aspx

Answer 4

If you are using .net Membership you could use

Membership.GetNumberOfUsersOnline()

More about it: http://msdn.microsoft.com/en-us/library/system.web.security.membership.getnumberofusersonline.aspx

Answer 5

If you'd like to implement the same mechanism by yourself, you can define like a CurrentUserManager class and implement the singleton pattern here. This singleton object of class CurrentUserManager would be unique in the AppDomain. In this class you will create its self instance once, and you will prohibit the others from creating new instances of this class by hiding its constructor. Whenever a request comes to this object, that single instance will give the response. So, if you implement a list that keeps the records of every user (when a user comes in, you add him to the list; when he goes out, you remove him from the list). And lastly, if you want the current user count you could just ask the list count to this singleton object.