SqlMembershipProvider.GetNumberOfUsersOnline returns the number of users for the current Membership.ApplicationName where the last-activity date is greater than the current time less the Membership.UserIsOnlineTimeWindow. The last-activity date/time stamp is updated to the current date and time when user credentials are validated by way of the Membership.ValidateUser(string, string) or Membership.UpdateUser(MembershipUser) method or when a call to a Membership.GetUser overload that takes no parameters or one that uses the userIsOnline parameter to specify that the date/time stamp should be updated.

Namespace: System.Web.Security
Assembly: System.Web (in System.Web.dll)
Assembly Versions: 2.0.0.0
Since: .NET 2.0