Interactive Services

An interactive service is a service that can interact with the application desktop. Other desktops do not receive user input. For more information, see Window Stations and Desktops.

An interactive service must run in the context of the LocalSystem account and be configured to run interactively. Services are configured to run interactively when the dwServiceType parameter in a CreateService call is set to include the SERVICE_INTERACTIVE_PROCESS flag. However, the following registry key contains a value, NoInteractiveServices, that controls the effect of the SERVICE_INTERACTIVE_PROCESS flag:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Windows

The NoInteractiveServices value defaults to 0, which means that services marked with the SERVICE_INTERACTIVE_PROCESS flag will be allowed to run interactively. When the NoInteractiveServices value is set to a nonzero value, no service started thereafter, regardless of whether it has been configured with SERVICE_INTERACTIVE_PROCESS, will be allowed to run interactively.

Note It is possible to display a message box from a service, even if it is not running in the LocalSystem account or not configured to run interactively. Simply call the MessageBox function using the MB_SERVICE_NOTIFICATION flag. Do not call MessageBox during service initialization or from the Handler routine, unless you call it from a separate thread, so that you return to the SCM in a timely manner.

It is also possible to interact with the desktop from a non-interactive service by modifying the DACLs on the interface window station and desktop or by impersonating the logged-on user and opening the interactive window station and desktop directly. For more information, see Interacting with the User by a Win32 Service.

Software for developers

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More information resources

MegaDetailed.Net
Unix Manual Pages
Delphi Examples