Am I Running as a Service

What works for me:

• The class doing the actual service work is running in a separate thread.
• This thread is started from within the OnStart() method, and stopped from OnStop().
• The decision between service and console mode depends on Environment.UserInteractive

Sample code:

class MyService : ServiceBase
{
    private static void Main()
    {
        if (Environment.UserInteractive)
        {
            startWorkerThread();
            Console.WriteLine ("======  Press ENTER to stop threads  ======");
            Console.ReadLine();
            stopWorkerThread() ;
            Console.WriteLine ("======  Press ENTER to quit  ======");
            Console.ReadLine();
        }
        else
        {
            Run (this) ;
        }
    }

    protected override void OnStart(string[] args)
    {
        startWorkerThread();
    }

    protected override void OnStop()
    {
        stopWorkerThread() ;
    }
}

I usually flag my Windows service as a console application which takes a command line parameter of "-console" to run using a console, otherwise it runs as a service. To debug you just set the command line parameters in the project options to "-console" and you're off!

This makes debugging nice and easy and means that the app functions as a service by default, which is what you'll want.

Another workaround.. so can run as WinForm or as windows service

var backend = new Backend();

if (Environment.UserInteractive)
{
     backend.OnStart();
     Application.EnableVisualStyles();
     Application.SetCompatibleTextRenderingDefault(false);
     Application.Run(new Fronend(backend));
     backend.OnStop();
}
else
{
     var ServicesToRun = new ServiceBase[] {backend};
     ServiceBase.Run(ServicesToRun);
}

Like Ash, I write all actual processing code in a separate class library assembly, which was then referenced by the windows service executable, as well as a console app.

However, there are occasions when it is useful to know if the class library is running in the context of the service executable or the console app. The way I do this is to reflect on the base class of the hosting app. (Sorry for the VB, but I imagine that the following could be c#-ified fairly easily):

Public Class ExecutionContext
    ''' <summary>
    ''' Gets a value indicating whether the application is a windows service.
    ''' </summary>
    ''' <value>
    ''' <c>true</c> if this instance is service; otherwise, <c>false</c>.
    ''' </value>
    Public Shared ReadOnly Property IsService() As Boolean
        Get
            ' Determining whether or not the host application is a service is
            ' an expensive operation (it uses reflection), so we cache the
            ' result of the first call to this method so that we don't have to
            ' recalculate it every call.

            ' If we have not already determined whether or not the application
            ' is running as a service...
            If IsNothing(_isService) Then

                ' Get details of the host assembly.
                Dim entryAssembly As Reflection.Assembly = Reflection.Assembly.GetEntryAssembly

                ' Get the method that was called to enter the host assembly.
                Dim entryPoint As System.Reflection.MethodInfo = entryAssembly.EntryPoint

                ' If the base type of the host assembly inherits from the
                ' "ServiceBase" class, it must be a windows service. We store
                ' the result ready for the next caller of this method.
                _isService = (entryPoint.ReflectedType.BaseType.FullName = "System.ServiceProcess.ServiceBase")

            End If

            ' Return the cached result.
            Return CBool(_isService)
        End Get
    End Property

    Private Shared _isService As Nullable(Of Boolean) = Nothing
#End Region
End Class