The developers who submit their .xap files for validation towards the persons who certify if an app is good to be used on the Marketplace or not, can experience two situations: their app to be approved, or not, because of a wrong .xap file. But what is this .xap file? According to dotnetspider.com, this is a compressed output file for Silverlight. The Silverlight application contains many resources, some of them being referred by the apps created by the Microsoft developers. Other files included by the .xap file are .dll files and appmanifest.xaml. The type of compression used by a .xap file is a .zip compression algorithm.
The .xap should be validated, so that the process to continue. If the file is not validated, you will receive a notification and you will know why the app was not approved. If the .xap file is validated, the app will be ready to download on the Marketplace or it will not be ready. This depends on your settings. You can set that the app or game to become available for users immediately after it receives the certificate or you can set the app to be ready for download after a certain period of time.
The .xap file is repackaged and it is sent to a mobile phone for testing. Of course, the phone runs on the operating system created by Microsoft for the mobile devices. The certification means that the app must pass the manual and also automatic testing. If the application is valid and passes all the tests, it is signed with your signature and it is ready for download. if the .xap file is validated, but the app fails to perform positively a requirement, you will get a failure report, where it will be explained why the application will not be published. If you update the app, your app is going to go through the same stages as a new application, so don’t be surprised if the period will be the same the next time when you will transmit an updated app to the Marketplace for download.11
