Public Class utente
    Public Property Nome As String = ""
    Public Property Indirizzo As String = ""
    Public Property DataConnessione As DateTime = Nothing

End Class


Public Class Utenti : Inherits Dictionary(Of String, utente)

End Class



Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs)
  Application.Lock()
  Application.Remove("utenti_collegati")
  Application.Add("utenti_collegati", New Utenti())
  Application.UnLock()
End Sub


Sub Application_End(ByVal sender As Object, ByVal e As EventArgs)
  Application.Lock()
  Application.Remove("utenti_collegati")
  Application.UnLock()
End Sub

Sub Session_Start(ByVal sender As Object, ByVal e As EventArgs)
  If System.Web.HttpContext.Current.User.Identity.IsAuthenticated Then
    Application.Lock()

    Dim utente As New utente()
    utente.Nome = System.Web.HttpContext.Current.User.Identity.Name
    utente.Indirizzo = Me.Request.UserHostAddress 'Me.Request.ServerVariables("remote_addr")
    utente.DataConnessione = DateTime.Now

    Dim utenti As Utenti = TryCast(Application("utenti_collegati"), Utenti)
    If utenti IsNot Nothing Then
      utenti.Add(Session.SessionID, utente)
    End If

    Application.UnLock()
  End If
End Sub

Sub Session_End(ByVal sender As Object, ByVal e As EventArgs)
  Application.Lock()
  Dim utenti As Utenti = TryCast(Application("utenti_collegati"), Utenti)
  utenti.Remove(Session.SessionID)

  Application.UnLock()
End Sub