Window phone 8 introduction
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The document discusses the architecture and app model of Windows Phone 8. It describes the core application architecture including the app container and core OS services. It covers the different app types, lifecycle events, transitions between foreground and background, tombstoning, fast resume state, and normal termination. It also discusses the page model for navigation and maintaining state across pages.
Window phone 8 introduction
- 1. Windows Phone 8 Architecture App Model and Navigation http://www.paxcel.net Contributors : - Pallavi Vasishta - pallavi.vasishta@paxcel.net Ranjan Baryal - ranjan.baryal@paxcel.net Paxcel technologies. www.paxcel.net This is the exclusive property of Paxcel Technologies. This may not be reproduced or given to third parties without their consent.
- 2. Windows Phone Architecture Note : Although Win32/COM APIs are only shown in the Core Application box , they are actually callable by managed apps, as well, as long as they are wrapped in a custom WinPRT component. Paxcel technologies. www.paxcel.net This is the exclusive property of Paxcel Technologies. This may not be reproduced or given to third parties without their consent.
- 3. App Types Paxcel technologies. www.paxcel.net This is the exclusive property of Paxcel Technologies. This may not be reproduced or given to third parties without their consent.
- 4. App’s Lifetime Management Events Paxcel technologies. www.paxcel.net This is the exclusive property of Paxcel Technologies. This may not be reproduced or given to third parties without their consent.
- 5. Transitions from Foreground App to Back stack The Closing case This is when an app terminates and receives the Closing event. This is unambiguous and simple to handle: it happens when a user presses the hardware Back button from the first page in the app, which kills the app instance and the process itself. The Deactivated case This is when an app is moved to the background and receives the Deactivated event. It happens when the user leaves your app in the back stack. The app must save sufficient transient state to recreate its current UI in case the user returns to the app instance, even if the process has been terminated in the meantime. – Tombstoning The app is deactivated and the process is killed, but the app instance is maintained. There’s nothing actively running or even sitting in memory, but the system remembers the app’s critical details and can bring it back to life if needed. – Fast app resume The app is deactivated and then immediately reactivated, without being tombstoned in between. Paxcel technologies. www.paxcel.net This is the exclusive property of Paxcel Technologies. This may not be reproduced or given to third parties without their consent.
- 6. Normal Termination Paxcel technologies. www.paxcel.net This is the exclusive property of Paxcel Technologies. This may not be reproduced or given to third parties without their consent.
- 7. Fast Resume State Paxcel technologies. www.paxcel.net This is the exclusive property of Paxcel Technologies. This may not be reproduced or given to third parties without their consent.
- 8. Tombstone State Paxcel technologies. www.paxcel.net This is the exclusive property of Paxcel Technologies. This may not be reproduced or given to third parties without their consent.
- 9. Some Fact About Deactivating App • In the fast app resume scenario, the IsApplicationInstancePreserved property is true on Application.Activated, whereas in the tombstone scenario, the IsApplicationInstancePreserved property is false on Application.Activated. • The system retains only five apps on the backstack, including the one that is currently active. As soon the user launches the sixth app, the app at the beginning of the backstack (that is, the one that was used least recently) is discarded completely. • If memory pressure increases to the point at which the system needs to reclaim memory from deactivated apps, it will first start tombstoning apps from the end of the back-stack. Paxcel technologies. www.paxcel.net This is the exclusive property of Paxcel Technologies. This may not be reproduced or given to third parties without their consent.
- 10. Resource Management During Deactivation of Apps • When App is Deactivate especially hardware resources such as sensors, and camera etc. , which can only be used by one app at a time can be deactivated using standard OnNavigatedFrom and Deactivated events. However, if you do not proactively release resources, the framework will do the job for you. It’s best to keep control of this yourself so that you can track which resources you were used and reinstate them as needed, if the app is later reactivated. Paxcel technologies. www.paxcel.net This is the exclusive property of Paxcel Technologies. This may not be reproduced or given to third parties without their consent.
- 11. Resuming The App • When an app is reactivated from the deactivated state, the framework resumes timers and threads, and reattaches some (but not all) resources that it previously detached. The developer is responsible for reconnecting/resuming media playback, HTTP requests, sockets, and the camera. Paxcel technologies. www.paxcel.net This is the exclusive property of Paxcel Technologies. This may not be reproduced or given to third parties without their consent.
- 12. Obscured And Cancelling Navigation Events • Some external operations Lock Button Pressed merely result in the app becoming temporarily obscured. In this scenario, there is no NavigatedFrom or Deactivated event. Instead, the system raises an Obscured event. • The system’s normal assumption is that if an app is running and the lock screen engages, it is reasonable to deactivate the app. • By disabling ApplicationIdleDetectionMode, the app can continue to run under screen lock. Then if you want to reduce battery consumption you will have to removes un necessary Resources yourself. • The Obscured event does not imply that the entire app UI is obscured. In many cases like for an incoming phone call, the UI is only partially obscured (at least until the call is accepted). the app does actually continue running, executing whatever operations it was performing when it was interrupted. • If you want to handle the Obscured and Unobscured events, you attach event handlers to the RootFrame object. • Cancelling Navigation Event - Navigations that are initiated by the user by interacting with your app UI can generally be cancelled,whereas navigations initiated by the user interacting with hardware buttons or initiated by the system generally cannot be cancelled. This can be accessed from NavigatingCancelEventArgs in NavigatedFrom Event. Paxcel technologies. www.paxcel.net This is the exclusive property of Paxcel Technologies. This may not be reproduced or given to third parties without their consent.
- 13. The Page Model • All the inter-app and intra-app instances are stored in a back stack as a collection of pages. • The inter-app backstack of app instances is limited to five apps but there is no hard limit to the number of intra-app pages that can be kept in the page backstack. • The app platform keeps track of which page (in a multipage app) the user was on when he navigated away. • The Creation order of pages might not be same as in original App. • One consequence of this is that the app should not rely on a hierarchical relationship between pages in terms of object lifetime. • Instead, all pages should be responsible for maintaining their own private state, and any state that is used across multiple pages should be held in the Viewmodel Paxcel technologies. www.paxcel.net This is the exclusive property of Paxcel Technologies. This may not be reproduced or given to third parties without their consent.
- 14. Thank You ! Paxcel technologies. www.paxcel.net This is the exclusive property of Paxcel Technologies. This may not be reproduced or given to third parties without their consent.