I want to ask how alarm applications work on mobile. As it doesn't drain battery, and i think in my problem (below) i can use same approach. And i don't know how to use background service, that it executes the main application with given period. I have to calculate something each time period which user inputs. And if the result is the same as user wants (user inputs it too) i need to show him about result. How i must make application: two apart applications (timer/calculator and input/output) or one application ? and if i write two apart applications, the 1st timer/calculator must be like console application?
And my main question: how to set "something" to given period, that with it i know that my calculator will calculate something with given period? P.S. Sorry for my English. And sorry for my mistakes if there are any