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Windows Services are very powerful. Using the abstractions that Delphi provides, you can also create an application that, reading a parameter on the command line, can act as a normal GUI application or as a Windows Service.

In the respective recipe folder, there is another recipe folder called 20_WindowsServiceOrGUI.

This application can be used as a normal Windows Service using the normal command-line switches used so far, but if launched with /GUI, it acts as a GUI application and can use the same application code (not TService). In our example, the GUI version uses the same worker thread as the service version. This can be very useful for debugging purposes also.

Run the application with the following command:

C:\<ExeProjectPath>\WindowsServiceOrGUI.exe /GUI  

You will get a GUI version of the service, as shown here: