title: Retry Post request when device is back online
body: <p>i have a small android app that makes some POST request to a server the problem is that i want that my app would be capable,when the request fails, of retrying the Post some time after checking the avaibility of the network on the device. How this can be done? is necessary to implement a service and a database to persist the data that i'm sending? i have read something about alarmmanager but i don't know how to implement this with my activity.</p>