When an application or set of data is captured into a Virtual Software Package, everything that is captured is contained in a layer. The layer represents all the files and registry settings that make up the virtualized application or data.
Typically, one layer is created for one application. However, one layer can contain multiple applications. Each layer is managed as a single entity.
The files and settings that were captured in a layer are stored in the SWV redirection area on the computer's hard drive. However, when a layer is active, all files and settings appear in the system just as they would if the application or data was installed on the computer. The way these files and settings appear to the user is accomplished through redirection, using the SWV File System Filter Driver.
There are two components or sublayers in a layer:
Contains all captured files and settings. The xpf packages that contain applications provide the read-only sublayer.
Contains any files or settings that the user of a layer adds or changes.
For example, you create a layer for Firefox. As a person uses Firefox, they may make some changes to the program. They may select a unique home page, add bookmarks, or change the original security settings. They may also install a browser plug-in. Those user changes are stored in the Writeable sublayer. The original files and settings are maintained in the Read-only sublayer.
Having these distinct sublayers is useful in being able to reset a layer. When a layer is reset, any data that was added by a user is deleted, and the layer is returned to its original configuration. Example: If a user's Firefox application ever becomes damaged, you can reset the layer to restore it to the way it was first deployed. The application does not have to be uninstalled or reinstalled.
Resetting layers also maintains specific versions and configurations of applications across your network. You can control how the applications are installed and configured on client computers.