I want to make an application that runs as a service. The application has no user interface. I want to create an MMC snap-in to set and change variables within this application. I might also want to create other applications that can link to that same instance of the "service" application to set and manipulate variables.

How could this be done? ActiveX.exe's or normal .exe with .dll?
How then would i specify in another app, that it must connect to that instance of the service, and not create a new one.