Windows 7 / Getting Started

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Device Containers

Because of the growing popularity of multifunction devices, such as printer/copier/fax /scanners, the PnP architecture has been enhanced in Windows 7 to support the detecting and grouping together of the different functions that a device supports. This new feature is called device container, a new PnP device property that groups device functions together into a single container representing the physical device. Device containers preserve the existing devnode model of Windows while providing users with a more natural representation of a physical device. (A devnode is an internal structure that represents a device on a system. It contains the device stack and information about whether the device has been started and which drivers have registered for notification on the device. Each device on a computer has a devnode, and these devnodes are organized into a hierarchical device tree. The Plug and Play Manager creates a devnode for a device when the device is configured.)

By using device containers, a multifunction device such as a printer/copier/fax/scanner can be presented to the user as a single device icon in the Devices And Printers folder (and also in the Device Stage interface if this is supported by the device). Device containers are identified by a container ID, which is a globally unique identifier (GUID) that is individual to each physical device. The container ID for a device is generated automatically by PnP. All devnodes belonging to the device container on a given bus share the same container ID.