Interfaces for Applications

This section describes interfaces used or implemented by applications using the Windows Media Device Manager SDK to communicate with devices. The term "application" used here means any executable, plug-in, or COM object that exists on a desktop computer and needs high-level communication with a connected portable device. This can include a media player application, a Windows Media Player plug-in (if it needs direct access to a portable device), or a play-count metering COM object.

Some of these interfaces are implemented by the application, while others are called by the application. The documentation for each interface indicates whether it is implemented or called (and if implemented, whether it is optional or required).

The following interfaces or classes are used by applications.

Interface or class	Description
CSecureChannelClient Class	A helper class that enables applications to authenticate themselves, encrypt and decrypt data, and create MACs.
IWMDeviceManager	The top level Windows Media Device Manager interface for applications.
IWMDeviceManager2	Extends IWMDeviceManager by providing advanced enumeration methods and other methods.
IWMDeviceManager3	Extends the IWMDeviceManager2 interface by providing a method that sets the device enumeration preference.
IWMDMDevice	Provides methods to examine and explore a single portable device.
IWMDMDevice2	Extends IWMDMDevice by making it possible to get the video formats supported by a device, find a storage by name, and use property pages.
IWMDMDevice3	Extends IWMDMDevice2 by providing methods to query a device for properties, send device I/O controle codes, and also providing upgraded methods to search for storages and retrieve device format capabilities.
IWMDMDeviceControl	Provides methods for controlling devices.
IWMDMDeviceSession	Improves the efficiency of device operations by bundling multiple operations into one session
IWMDMEnumDevice	Enumerates portable devices attached to a computer.
IWMDMEnumStorage	Enumerates storages on a device.
IWMDMMetaData	Sets and retrieves metadata properties (such as artist, album, genre, and so on) of a storage.
IWMDMObjectInfo	Gets and sets information that controls how playable files on device are handled by the IWMDMDeviceControl interface
IWMDMRevoked	Retrieves the URL from which updated components can be downloaded, if a transfer fails with a revocation error.
IWMDMStorage	Provides methods to examine and explore a storage (file, folder, playlist) on a device.
IWMDMStorage2	Extends IWMDMStorage by making it possible to get a child storage by name, and to get and set extended attributes.
IWMDMStorage3	Extends IWMDMStorage2 by exposing metadata.
IWMDMStorage4	Extends IWMDMStorage3 by providing methods for retrieving a subset of available metadata for a storage, and for setting and retrieving a list of references to other storages.
IWMDMStorageControl	Used to insert, delete, or move files within a device, or between a device and the computer.
IWMDMStorageControl2	Extends IWMDMStorageControl by making it possible to set the name of the destination file when inserting content into a storage.
IWMDMStorageControl3	Extends IWMDMStorageControl2 by making it possible to pass in an IWMDMMetaData interface pointer.
IWMDMStorageGlobals	Provides methods for retrieving global information about a storage medium (such as a flash ROM card) on a device.
IWMDRMDeviceApp	Enables an application to perform metering, license synchronization, and update of a device's DRM components.
IWMDRMDeviceApp2	Extends IWMDRMDeviceApp by providing a new version of the QueryDeviceStatus method.

Callback Interfaces

The following optional interfaces are implemented by an application in order to track the progress of an asynchronous request, such as a read or write request.

Interface	Description
IWMDMNotification	Allows applications and service providers to receive notifications when devices or memory storages (such as RAM cards) are connected or disconnected from the computer.
IWMDMOperation2	Extends IWMDMOperation by providing methods to get and set extended attributes.
IWMDMOperation3	Extends IWMDMOperation by providing a new method for transferring data unencrypted for added efficiency.
IWMDMOperation	Allows an application to control how data is read from or written to the computer during a file transfer.
IWMDMProgress2	Extends the IWMDMProgress::End method by providing a status indicator.
IWMDMProgress3	Extends IWMDMProgress2 by providing additional input parameters to specify the event ID and context-specific information.
IWMDMProgress	Allows an application to track the progress of operations, such as formatting media or file transfers.

The following diagram shows how most of the important application interfaces are acquired from the root IWMDeviceManager interface. An application gets this root interface by cocreating the MediaDevMgr object, requesting the IComponentAuthenticate interface, authenticating the component, and then requesting the IWMDeviceManager (these steps are described in Authenticating the Application). Once this root interface has been acquired, IWMDeviceManager::EnumDevices is called to create an object that implements IWMDMEnumDevice. Other interfaces are obtained by calling methods on interfaces in the order shown. Derived interfaces such as IWMDMDevice2 are obtained by calling QueryInterface on the base interface.

In the following diagram, derived interfaces are labeled by slash marks, so "IWMDMStorage/2/3" would indicate IWMDMStorage, IWMDMStorage2, and IWMDMStorage3.

See Also

• Programming Reference