Other Is there possable to create a service app on windows ?

You can pack jar as exe file with launch4j (jre needed) : https://www.b4x.com/android/forum/threads/35863/#content

Then the .exe file can be started by win7 tasker.

Commons-daemon procrun may be another option (not tested)
http://commons.apache.org/proper/commons-daemon/procrun.html