/// <summary>
/// Shutdown all sessions.
/// </summary>
public async static Task SessionShutdownAsync()
{
try
{
while (OpcSessions.Count > 0)
{
OpcSession opcSession = null;
try
{
await OpcSessionsListSemaphore.WaitAsync();
opcSession = OpcSessions.ElementAt(0);
OpcSessions.RemoveAt(0);
}
finally
{
OpcSessionsListSemaphore.Release();
}
await opcSession?.ShutdownAsync();
}
}
catch (Exception e)
{
Logger.Fatal(e, "Failed to shutdown all sessions.");
}
// Wait and continue after a while.
uint maxTries = ShutdownWaitPeriod;
while (true)
{
int sessionCount = OpcSessions.Count;
if (sessionCount == 0)
{
return;
}
if (maxTries-- == 0)
{
Logger.Information($"There are still {sessionCount} sessions alive. Ignore and continue shutdown.");
return;
}
Logger.Information($"{ProgramName} is shutting down. Wait {SessionConnectWaitSec} seconds, since there are stil {sessionCount} sessions alive...");
await Task.Delay(SessionConnectWaitSec * 1000);
}
}
/// <summary>
/// Create the data structures to manage OPC sessions and actions.
/// </summary>
/// <returns></returns>
public static async Task <bool> CreateOpcActionDataAsync()
{
try
{
await OpcActionListSemaphore.WaitAsync();
await OpcSessionsListSemaphore.WaitAsync();
// create actions out of the configuration
var uniqueEndpointUrls = _actionConfiguration.Select(n => n.EndpointUrl).Distinct();
foreach (var endpointUrl in uniqueEndpointUrls)
{
// create new session info.
OpcSession opcSession = new OpcSession(endpointUrl, _actionConfiguration.Where(n => n.EndpointUrl == endpointUrl).First().UseSecurity, OpcSessionCreationTimeout);
// add all actions to the session
List <OpcAction> actionsOnEndpoint = new List <OpcAction>();
var endpointConfigs = _actionConfiguration.Where(c => c.EndpointUrl == endpointUrl);
foreach (var config in endpointConfigs)
{
config?.Read.ForEach(r => opcSession.OpcActions.Add(new OpcReadAction(r)));
config?.Write.ForEach(w => opcSession.OpcActions.Add(new OpcWriteAction(w)));
}
// add session.
OpcSessions.Add(opcSession);
}
}
catch (Exception e)
{
Logger.Fatal(e, "Creation of the internal OPC management structures failed. Exiting...");
return(false);
}
finally
{
OpcSessionsListSemaphore.Release();
OpcActionListSemaphore.Release();
}
return(true);
}