What can Services do under Windows?

Question

Does anyone have a good guide to capabilities of Windows Services under XP? In particular, I am trying to find out what happens when a program being run as a service tries t

Answer 1

Generally, services should be designed to not have any visible UI. The entire point of a service is to run in the background, without UI, unattended. (Think SQL Server, IIS, etc.)

In most scenarios, a separate application controls the service's operation, should a GUI be needed. (Continuing the samples I just mentioned, SQL Server Management Studio, IIS Manager, etc.) These separate applications configure and manipulate the service (and occasionally, if needed, bounce said service).

If your service requires occasional UI, and said UI can't be isolated to a control app, then you probably should reconsider the fact that you're using a service to begin with. Perhaps a UI application which resides in the system notification area is the right pattern to use? (E.G., Windows Live Communicator.)