List all active ASP.NET Sessions

Question

How can I list (and iterate through) all current ASP.NET sessions?

Answer 1

You can collect data about sessions in global.asax events Session_Start and Session_End (only in in-proc settings):

private static readonly List<string> _sessions = new List<string>();
private static readonly object padlock = new object();

 public static List<string> Sessions
 {
       get
       {
            return _sessions;
       }
  }

  protected void Session_Start(object sender, EventArgs e)
  {
      lock (padlock)
      {
          _sessions.Add(Session.SessionID);
      }
  }
  protected void Session_End(object sender, EventArgs e)
  {
      lock (padlock)
      {
          _sessions.Remove(Session.SessionID);
      }
  }

You should consider use some of concurrent collections to lower the synchronization overhead. ConcurrentBag or ConcurrentDictionary. Or ImmutableList

https://msdn.microsoft.com/en-us/library/dd997373(v=vs.110).aspx

https://msdn.microsoft.com/en-us/library/dn467185.aspx

Answer 2

Here's a WebForms/Identity example that gets a list of the logged on users active within the last 30 minutes.

The answer below works for a single web server, and the cache will be lost if the application restarts. If you want to persist the data and share it between servers in a web farm, this answer might be of interest.

In Global.asa.cs:

public static ActiveUsersCache ActiveUsersCache { get; } = new ActiveUsersCache();

and

protected void Application_PreRequestHandlerExecute(object sender, EventArgs e)
{
    if (User != null && User.Identity.IsAuthenticated)
    {
        // Only update when the request is for an .aspx page
        if (Context.Handler is System.Web.UI.Page)
        {
            ActiveUsersCache.AddOrUpdate(User.Identity.Name);
        }
    }
}

The add these couple of classes:

public class ActiveUsersCache
{
    private readonly object padlock = new object();
    private readonly Dictionary<string, DateTime> cache = new Dictionary<string, DateTime>();
    private DateTime lastCleanedAt;

    public int ActivePeriodInMinutes { get; } = 30;
    private const int MinutesBetweenCacheClean = 30;

    public List<ActiveUser> GetActiveUsers()
    {
        CleanCache();

        var result = new List<ActiveUser>();
        lock (padlock)
        {
            result.AddRange(cache.Select(activeUser => new ActiveUser {Name = activeUser.Key, LastActive = activeUser.Value}));
        }
        return result;
    }

    private void CleanCache()
    {
        lastCleanedAt = DateTime.Now;
        var cutoffTime = DateTime.Now - TimeSpan.FromMinutes(ActivePeriodInMinutes);
        lock (padlock)
        {
            var expiredNames = cache.Where(au => au.Value < cutoffTime).Select(au => au.Key).ToList();
            foreach (var name in expiredNames)
            {
                cache.Remove(name);
            }
        }
    }

    public void AddOrUpdate(string userName)
    {
        lock (padlock)
        {
            cache[userName] = DateTime.Now;
        }

        if (IsTimeForCacheCleaup())
        {
            CleanCache();
        }
    }

    private bool IsTimeForCacheCleaup()
    {
        return lastCleanedAt < DateTime.Now - TimeSpan.FromMinutes(MinutesBetweenCacheClean);
    }
}

public class ActiveUser
{
    public string Name { get; set; }

    public DateTime LastActive { get; set; }

    public string LastActiveDescription
    {
        get
        {
            var timeSpan = DateTime.Now - LastActive;
            if (timeSpan.Minutes == 0 && timeSpan.Seconds == 0)
                return "Just now";
            if (timeSpan.Minutes == 0)
                return timeSpan.Seconds + "s ago";
            return $"{timeSpan.Minutes}m  {timeSpan.Seconds}s ago";
        }
    }
}

Finally, in the page where you want to display the active users, display the results:

UserRepeater.DataSource = Global
    .ActiveUsersCache.GetActiveUsers().OrderByDescending(u => u.LastActive);
UserRepeater.DataBind();

Answer 3

I've been looking around for an equivalent of @ajitdh's answer for later versions of ASP.net - couldn't find anything, so thought I'd update this thread with solution for v4.6.2... Haven't tested with later versions of .net, but it doesn't work with v4.5. I am guessing it will be compatible with v4.6.1 onward.

Cache cache = HttpRuntime.Cache;
MethodInfo method = typeof( System.Web.Caching.Cache ).GetMethod( "GetInternalCache", BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.FlattenHierarchy );

object objx = method.Invoke( cache, new object[] { false } );

FieldInfo field = objx.GetType().GetField( "_cacheInternal", BindingFlags.NonPublic | BindingFlags.FlattenHierarchy | BindingFlags.Instance );
objx = field.GetValue( objx );

field = objx.GetType().GetField( "_cachesRefs", BindingFlags.NonPublic | BindingFlags.FlattenHierarchy | BindingFlags.Instance );
objx = field.GetValue( objx );

IList cacherefs = ( (IList)objx );
foreach( object cacheref in cacherefs )
{
    PropertyInfo prop = cacheref.GetType().GetProperty( "Target", BindingFlags.FlattenHierarchy | BindingFlags.Public | BindingFlags.Instance );

    object y = prop.GetValue( cacheref );

    field = y.GetType().GetField( "_entries", BindingFlags.NonPublic | BindingFlags.FlattenHierarchy | BindingFlags.Instance );

    Hashtable c2 = (Hashtable)field.GetValue( y );
    foreach( DictionaryEntry entry in c2 )
    {
        object o1 = entry.Value.GetType().GetProperty( "Value", BindingFlags.NonPublic | BindingFlags.Instance ).GetValue( entry.Value, null );

        if( o1.GetType().ToString() == "System.Web.SessionState.InProcSessionState" )
        {
            SessionStateItemCollection sess = (SessionStateItemCollection)o1.GetType().GetField( "_sessionItems", BindingFlags.NonPublic | BindingFlags.Instance ).GetValue( o1 );

            if( sess != null )
            {
                // Do your stuff with the session!
            }
        }
    }
}

Answer 4

you can also try this as something basic, this is only so you can understand the concept

protected void Page_Load(object sender, EventArgs e)
    {
        if (Convert.ToInt32(Session["islogged"]) == 0)
        {
            Label1.Text = "you are not logged";
        }

    }

    protected void logged(object sender, EventArgs e)

/* add it to a button so the looged in button when it is clicked this will appear*/ {

            Label1.Text = "you are  Logged in "; 


    }

Answer 5

To the best of my knowledge, with standard in-memory sessions you cannot. This is something I was grappling with last week and I came to the determination that it isn't possible unless you are using a session state server. Seems rather odd from a design standpoint if you ask me. :/

Answer 6

Try the following code

 for (int i = 0; i < Session.Keys.Count - 1; i++)
        {
            Label1.Text += Session.Keys.Get(i) + " - " + Session[i].ToString()+"<br/>";
        }