Windows Service Applications

1. Windows Service Applications • A Windows Service application consists of two parts: • The application executable. • The services derived from the ServiceBase class. • In the application executable, you implement the Main method to control the applications services. • To create any Windows Service application, you must have a class derived from the ServiceBase class. • The ServiceBase class implements virtual methods for functionality required by the Service Control Manager (SCM).

2. Windows Service Applications • A Windows Service application has the following characteristics: • Does not have a UI. • It is designed to run for a very long time. • The execution of the Windows Service application is separate from the services execution and functionality.

3. Windows Service Applications • You start and stop the Windows Service application executable independently of starting and stopping the service. • A Windows Service application can run without a user being logged on to the machine. • Typically, a Windows Service application runs under the System Account, but a specific account can be provided.

4. Windows Service Applications • Although the executable may always be running, the service can be stopped, started, paused, or continued. • The SCM uses the ServiceBase class’s OnStop, OnStart, OnPause, OnContinue, and OnShutdown (of the machine) methods to control the service’s behavior. • The service can also set property values like CanStop, CanPauseAndContinue, and CanShutdown to inform the SCM which methods are supported.

5. Windows Service Applications • Once a Windows Service application is installed, the Service Control Manager (SCM) executes the application and the Main method is run. • The Main method performs any application initialization code and then creates the services within the executable.

6. Computer Management Console with SCM Selected

7. Debugging Windows Services Applications • Debugging is a process of finding the cause of errors in a program, locating the lines of code that are causing those errors, and fixing those errors. • Visual Studio provides a number of tools that provide a streamlined approach to debugging all kind of applications such as Windows Forms, Windows Services ,and Console Applications.

8. Common Debugging Mechanisms • Breakpoint • Quick Watch Window • Watch Window • Output Window • Immediate Window • Locals Window • Call Stack Window • Threads Window • Memory Window

9. Debugging a Window Service Application • A Windows Service application is always executing with one or more services running internally. • To debug, you must first attach to the Windows Services application: then you will have the standard Visual Studio debugging tools available. • The Attach Process is the procedure used by Visual Studio to monitor an already running executable and allow debugging.

10. Attach to Process Editor

11. Summary • You learned how to create a Windows Form event, some of the common Windows Form events, and how to handle a Raised event. • You learned how to create a WPF event, the differences among bubbled, tunneled, and direct WPF events, and how to handle a Raised event throughout the control hierarchy. • You learned about the Windows Services application, the ServiceBase class, and how to override the ServiceBase class default methods. • You learned how to debug Windows Services applications using the Attach Process Editor and the common debugging windows.