Windows 8 Application Deployment: AppX

Today we’re going to take a look at how applications on Windows 8 will be deployed. Microsoft has been tight lipped about this, but its certain that Windows 8 will have a built-in application store. Applications found in there will be deployed using the AppX format.

Windows 8 will ship with a built-in PDF reader, deployed using AppX, and even though the application doesn’t work in the latest build, the application files shed some light on how application deployment will work on Windows 8.

1: AppX Overview

The core part of the AppX application is a XAML file which described the application, similar to Windows Phone 7. Unlike WP7, there will be much more information in this XAML file. This’ll probably be used by the Application Store, and other applications able to interact with that application. Long Zheng has taken a look at this in April, highlighting several of the possible attributes found in the file.

  • Application identity – name, publisher, version
  • Application architecture – processor architecture, type of application, framework required, operating system version
  • Dependencies – name, publisher and minimum version of other required applications
  • Capabilities – networking, file system and profile capabilities requested by the application
  • OS extensions – associated filetypes and protocols, AutoPlay, “Charms”, notifications, splash screen
  • Tile customization – logo, name, description and colors for the tile-based user interface

2: The Windows Store

Microsoft has been thinking about a store for a very long time. Back in June 2010, a lengthy Windows 8 powerpoint leaked and revealed concept images for a Windows 8 store. Note that the Windows Chrome isn’t present, and they might’ve started working on the Immersive UI by then.

A tile linking to the store, with an icon resembling the Wii Shop Channel, is present on the D9 build, though they didn’t show it during the demo (and the tile was probably locked). This does raise several questions:

  1. Will the Store be the only location to download specific Windows 8 Immersive software?
  2. Can you install legacy applications on the new interface, or will you be switched to the regular desktop when running a setup file.
  3. Will you be able to install an Immersive application trough the legacy desktop?
  4. Will the Store also feature content for Windows Phone 7?
  5. Will the Store feature classic Windows applications meant for the regular desktop?
  6. How will application submission work?
  7. How will the payment options work? Zune Pass or Microsoft Cards anyone?
3: AppX in Build 7989
The PDF reader, even though it doesn’t work is deployed by AppX. You can find the application under \Program Files\Microsoft\Windows.glcnd\. In here you can see some XAML files for the UI and also the manifest file AppxManifest as discussed above. You’ll also find a command script file, which uses the InstallAppX command to install a package. The process is simple, and similar to Ubuntu’s apt-get terminal command: open the command prompt and write InstallAppX *path to application folder*. This is probably the thing that the Marketplace application will do in the background, (albeit with additional parameters)
Many questions like the specifics of this new application model, the future of Silverligth/WPF and the use of new IDE’s remains unanswered, at least for now, Microsoft hopes to address this at their upcoming //BUILD conference in September.
On a side note: The PDF reader is called “Modern Reader” in the XAML file, a metro folder image and XAML markup files for a Save Menu, Command Bar and Summary Pane can be found in the application folder…. Perhaps this modern reader is just a little more than a normal PDF reader?
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