private void CloseHosts()
{
networkModel.SaveNetworkModel();
if (hosts == null || hosts.Count == 0)
{
throw new Exception("Network Model Services can not be closed because it is not initialized.");
}
foreach (ServiceHost host in hosts)
{
host.Close();
}
string message = "The Network Model Service is gracefully closed.";
Logger.LogInfo(message);
Console.WriteLine("\n\n{0}", message);
}