As the documentation says, OS provides you with merely 25 sec to complete your work on PeriodicTask launch.
I have a long list of commands to be sent to the server in the background. So how do i make sure to save back the unsent stuff back to IsolatedStorage before my 25 sec gets over. Do i get terminating/finishing or some similar notification?

And while searching for this i came across this. Which says if NotifyComplete() is not called in the OnInvoke() i may face problems for subsequent PeriodicTask launches. So how do i make sure to call NotifyComplete() every time.