Develop Reference

C# - error while sending email from outlook

I have a C# exe which sends email from Outlook, it works fine if run manually.
I am trying to run it through Task scheduler but it gives following error:
System.Runtime.InteropServices.COMException (0x80080005): Retrieving the COM class factory for component with CLSID {0006F03A-0000-0000-C000-000000000046} failed due to the following error: 80080005 Server execution failed (Exception from HRESULT: 0x80080005 (CO_E_SERVER_EXEC_FAILURE)).
at sendMail.Program.Main(String[] args) in D:\Recovered\Root\Projects\sendMail\sendMail\Program.cs:line 20

I have found a hack. I could fix the exception but it was sending emails as Microsoft does not allow COM objects to operate through a service (in my case Task Scheduler).
I created a script and triggered command from it every few hours as needed, since it was running as a program and not a service, it works fine, the only disadvantage being sleep calls invoked from my script.

Microsoft's manual provides this:
Cause: If many COM+ applications run under different user accounts
that are specified in the This User property, the computer cannot
allocate memory to create a new desktop heap for the new user.
Therefore, the process cannot start.
WORKAROUND: To work around this problem, modify the value of the
following registry subkey:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session
Manager\SubSystems\Windows

Outlook is a singleton - COM system will refuse to marshal calls between two processes running in different security contexts.

Unit testing Microsoft Band

Trying to do unit testing using MSTest in VS2015 with the Microsoft Band nuGet package and running into the following error
"Microsoft.Band.BandIOException: An error occurred while attempting to acquire the Bluetooth device service.
This error can occur if the paired device is unreachable or has become unpaired from the current host.
System.InvalidOperationException: A method was called at an unexpected time. (Exception from HRESULT: 0x8000000E)".
Code runs fine when run inside the application. It fails on the line to call BandClientManager.Instance.ConnectAsync.

The exception and error message are not helpful here, but you must establish Bluetooth connections on a UI thread. This is because the app might prompt the user and ask if they want to allow access to the Bluetooth device.
For example, in a UWP app, you can do the following to ensure UI thread execution:
await Windows.ApplicationModel.Core.CoreApplication.MainView.Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, async () =>
{
IBandClient client = await BandClientManager.Instance.ConnectAsync(...);
...
});
Alternatively, if you have access to a UI control, you can use its Dispatcher directly.
Any code that ultimately calls BluetoothLEDevice.FromBluetoothAddressAsync must do it on a UI thread. The Bluetooth access prompt will happen whenever the app package manifest (.appxmanifest) changes.
I can't imagine this fix being dependable for unit tests since there's no UI. I'm not sure what the intended fix is besides mocking the client interfaces and just avoiding Bluetooth altogether.

How to make window service to restart on error

I am having MSMQ on windows 2008. Messages are available in private queue. I have one WCF subscriber (written in C#) which is installed as windows service. Now problem is that sometimes the WCF subscriber stops picking messages from Queue. If I restart service again it works fine. Now I attached IError Handler to log the reason and exception.
Now to Handle this issue what I wanted to do is, I will set the recovery property to restart service on first failure and now problem is how to throw the error from HandleError() method of IErrorHandler class?
Please tell me best way to throw an exception in a window service so it can be restarted.

While it is probably better to address the underlying cause of your exceptions, it is certainly valid in certain scenarios to implement a fail fast methodology. Indeed, this ability to kill processes which have become "flawed" in some manner is critical to the concept of fault tolerance.
So, to make a windows service commit suicide:
void KillSelf()
{
try
{
// Code to close open connections/dispose
// of unmanaged resources etc
...
}
finally
{
Environment.Exit(1);
}
}
Service recovery options should be set to restart automatically. This will ensure your service comes straight back up again.

As far as I know one cannot throw an exception to restart a windows service.
I usually encapsulate a try catch (with logging) to prevent any exceptions crashing the service, which is the opposite to what you are suggesting.
It may be that you can catch an error and stop the service (not sure) and configure the service to restart if it stops?

Error while stopping windows service

I am working on Windows Service. It works fine. When i am trying to stop the service from services.msc, it throws the following error:
Windows could not stop the xxx service on Local Computer.
The service did not return an error. This could be an internal Windows error or an internal service error.
If the problem persists, contact your system administrator.
If I try to stop it again, it takes lots of time and then throws the error as below:
Windows could not stop the xxx service on Local Computer.
Error 1061: The service cannot accept control messages at this time.
At this point, the service has stopped. But if I try to reinstall the service, it throws another error:
Windows could not stop the xxx service on Local Computer.
Error 1001: The specified service is marked for deletion.
After closing services.msc, it lets me reinstall the service and again things start working fine.
In OnStop(), I am doing some lengthy operations and it takes time to complete.
Any idea how I can make the whole thing go smoothly?
--Edit--
This is what my OnStop method looks like:
protected override void OnStop()
{
base.OnStop();
//Some lengthy operation
}

The windows service have a default timeout in onstart and onstop events. Normally if you are doing time consuming operations in any of these events start a new thread and let the operation to perform in background.
Usually the OnStart as well as OnStop events within the windows service are used to initiate a process and the time consuming process will carryout it's execution within a child thread.
Hope this will solve your issue..

There is a registry entry that controls how much time windows gives services to shut down before giving up: http://support.microsoft.com/kb/146092
Trivially, increasing this time would fix the issue, assuming that your service is actually shutting down after that long operation.

My EventWaitHandle says "Access to the path is denied", but its not

Quick summary with what I now know
I've got an EventWaitHandle that I created and then closed. When I try to re-create it with this ctor, an "Access to the path ... is denied" exception is thrown. This exception is rare, most of the times it just re-creates the EventWaitHandle just fine. With the answer posted below (by me), I'm able to successfully call EventWaitHandle.OpenExisting and continue on in the case that an exception was thrown, however, the ctor for EventWaitHandle should have done this for me, right? Isn't that what the out parameter, createdNew is for?
Initial question
I've got the following architecture, a windows service and a web service on the same server. The web service tells the windows service that it has to do work by opening and setting the wait handle that the windows service is waiting on.
Normally everything is flawless and I'm able to start / stop the windows service without any issue popping up. However, some times when I stop the web service and then start it up again, it will be completely unable to create the wait handle, breaking the whole architecture.
I specifically need to find out what is breaking the event wait handle and stop it. When the wait handle "breaks", I have to reboot windows before it will function properly again and thats obviously not ideal.
UPDATE: Exception thrown & Log of Issue
I rebooted the windows service while the web service was doing work in hopes of causing the issue and it did! Some of the class names have been censored for corporate anonymity
12:00:41,250 [7] - Stopping execution due to a ThreadAbortException
System.Threading.ThreadAbortException: Thread was being aborted.
at System.Threading.Thread.SleepInternal(Int32 millisecondsTimeout)
at OurCompany.OurProduct.MyClass.MyClassCore.MonitorRequests()
12:00:41,328 [7] - Closing Event Wait Handle
12:00:41,328 [7] - Finally block reached
12:00:42,781 [6] - Application Start
12:00:43,031 [6] - Creating EventWaitHandle: Global\OurCompany.OurProduct.MyClass.EventWaitHandle
12:00:43,031 [6] - Creating EventWaitHandle with the security entity name of : Everyone
12:00:43,078 [6] - Unhandled Exception
System.UnauthorizedAccessException: Access to the path 'Global\OurCompany.OurProduct.MyClass.EventWaitHandle' is denied.
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.Threading.EventWaitHandle..ctor(Boolean initialState, EventResetMode mode, String name, Boolean& createdNew, EventWaitHandleSecurity eventSecurity)
at OurCompany.OurProduct.MyClassLibrary.EventWaitHandleFactory.GetNewWaitHandle(String handleName, String securityEntityName, Boolean& created)
at OurCompany.OurProduct.MyClassLibrary.EventWaitHandleFactory.GetNewEventWaitHandle()
at OurCompany.OurProduct.MyClass.MyClassCore..ctor()
Rough timeline:
11:53:09,937: The last thread on the web service to open that existing wait handle, COMPLETED its work (as in terminated connection with the client)
12:00:30,234: The web service gets a new connection, not yet using the wait handle. The thread ID for this connection is the same as the thread ID for the last connection at 11:53
12:00:41,250: The windows service stops
12:00:42,781: The windows service starts up
12:00:43,078: The windows service finished crashing
12:00:50,234: The web service was actually able to open the wait handle call Set() on it without any exception thrown etc.
12:02:00,000: I tried rebooting the windows service, same exception
12:36:57,328: After arbitrarily waiting 36 minutes, I was able to start the windows service up without a full system reboot.
Windows Service Code
Initialization:
// I ran into security issues so I open the global EWH
// and grant access to Everyone
var ewhSecurity = new EventWaitHandleSecurity();
ewhSecurity.AddAccessRule(
new EventWaitHandleAccessRule(
"Everyone",
EventWaitHandleRights.Synchronize | EventWaitHandleRights.Modify,
AccessControlType.Allow));
this.ewh = new EventWaitHandle(
false,
EventResetMode.AutoReset,
#"Global\OurCompany.OurProduct.MyClass.EventWaitHandle",
out created,
ewhSecurity);
// the variable "created" is logged
Utilization:
// wait until the web service tells us to loop again
this.ewh.WaitOne();
Disposal / closing:
try
{
while (true)
{
// entire service logic here
}
}
catch (Exception e)
{
// should this be in a finally, instead?
if (this.ewh != null)
{
this.ewh.Close();
}
}
Web Service Code
Initialization:
// NOTE: the wait handle is a member variable on the web service
this.existing_ewh = EventWaitHandle.OpenExisting(
#"Global\OurCompany.OurProduct.MyClass.EventWaitHandle");
Utilization:
// wake up the windows service
this.existing_ewh.Set();
Since the EventWaitHandle is a member variable on the web service, I don't have any code that specifically closes it. Actually, the only code that interacts with the EventWaitHandle on the web service is posted above.
Looking back, I should probably have put the Close() that is in the catch block, in a finally block instead. I probably should have done the same for the web service but I didn't think that it was needed.
At any rate, can anyone see if I'm doing anything specifically wrong? Is it crucially important to put the close statements within a finally block? Do I need to manually control the Close() of the existing_ewh on the web service?
Also, I know this is a slightly complex issue so let me know if you need any additional info, I'll be monitoring it closely and add any needed information or explanations.
Reference material
EventWaitHandleSecurity Class
EventWaitHandleAccessRule Class
EventWaitHandle Class

In the code that creates the wait handle on the windows service, if it fails (as in access denied), you could try to "open an existing wait handle" via
EventWaitHandle.OpenExisting(
#"Global\OurCompany.OurProduct.MyClass.EventWaitHandle",
EventWaitHandleRights.Synchronize | EventWaitHandleRights.Modify);
Though, I'm not entirely sure if the behaviour would stay the same at that point.
Note: I'd appreciate feedback. Its a potential answer so I'm answering my own question, again, plenty of comments are quite welcome!
Note 2: Amazingly, applying EventWaitHandleRights.FullControl instead of the above flags (Synchronize + Modify) doesn't work well. You must use the sample above.

MSDN says:
UnauthorizedAccessException - The named event exists and has access control security, but the user does not have EventWaitHandleRights.FullControl.
and
The caller has full control over the newly created EventWaitHandle object even if eventSecurity denies or fails to grant some access rights to the current user.
Your service has no rights to get the existing event via EventWaitHandle constructor. (EventWaitHandleRights.FullControl is not specified. And your named event exists while it has opened handles on it.) You can open the existing event using EventWaitHandle.OpenExisting.