Windows Phone 7.1 (Mango) OData uses a different approach for tombstoning the Data Service State of an application. In this tutorial, we take a WP 7.0 application and convert it to WP 7.1.
In Mango OData, methods have been added to the DataServiceState class that improves performance and functionality when storing client state. You can now serialize nested binding collections as well as any media resource streams that have not yet been sent to the data service.
The conversion of the WP 7.0 application to WP 7.1 involves targeting the application to WP 7.1, revising the client data classes to support serialization, and modifying the App.xaml’s Application_Deactivated and Application_Activated events to use the new DataServiceState’s Serialize and Deserialize methods.