Windows service and return value?

[Passero]

I've written a windows service and it runs but now there is a thing i
want to do and i'm not sure it is possible.
I now want to write an application that uses that service. It has to
give a parameter to the service and it wants a return value. Is it
possible and if yes, how can i do so?

It can not be a webservice because of security reasons and so on