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Windows 8 programming with html and java script

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A few slides to get people familiar with Windows 8 applications in JavaScript - WinJS, app lifecycle, app container, and more

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Windows 8 programming with html and java script

  1. 1. Chad McCallum ASP.NET/IIS MVP iQmetrix Software http://www.rtigger.com@ChadEmm / chadm@iqmetrix.com
  2. 2. Windows RT API Windows Runtime is implemented at a low-level and then “projected” into C++, C#, VB, and JavaScript APIs Allows the APIs to present the same functionality in a way that’s familiar to developers of that language
  3. 3. Native App in HTML? Apps are run in an Internet Explorer 10 shell This means:  Can include other JS libraries  HTML5 and CSS3 support for user interface  Can do (almost) anything you’d do with a web application
  4. 4. What are these apps called? Windows Store apps  Acquired, installed, and updated via the Windows Store app  Packaged into an “.appx” file when submitted  Contains a manifest file that describes the app, the resources it uses (camera, network, etc.), and lists OS integrations (background tasks, file associations, etc.)
  5. 5. Windows Library for JavaScript aka WinJS Wrapper for Windows Runtime API Provides:  Access to system-level resources  HTML implementation of WinRT controls, complete with CSS styling and events  CSS3-based animation framework  Helpers for common coding patterns
  6. 6. Not Quite a Web Page Some DOM API calls are modified or unavailable, like alert or window.open There are some methods, properties, and CSS queries that are specific to a Windows Store app Allowed to make cross-domain requests, load resources from remote sources
  7. 7. Not Quite a Web Page Not allowed to reference scripts remotely IFrames are run in “web context” without access to WinRT Some DOM-based calls are modified or removed (document.write, innerHTML)
  8. 8. App Container Run within a dedicated environment that can’t access other applications and the system directly Have unrestricted read/write access to their own appdata folders Access to any other files or hardware goes through a broker, which can deny access
  9. 9. App Lifecycle 4-ish states  Starting: shows splash screen image, does all the app initialization behind the scenes  Running: active application on user’s device  Suspending: app has lost focus, 5 seconds to save state  Resuming: app has regained focus  Suspended: still in memory, but not allocated any CPU time  Terminated: removed from memory, effectively closed. OS triggers this at will, app is not informed
  10. 10. App State When being “suspended”, Windows 8 gives your app approximately 5 seconds to save its state Can save data as Temp, Local, and Roaming  Save as a file and/or key-value pairs  Always app-specific, as they’re saved relative to your app’s directory  Roaming settings are uploaded to user’s Microsoft Account and are accessible across devices
  11. 11. Code Time!

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