Windows Live Photo Gallery Publishing Plug-in Architecture
The publishing plug-in platform communicates with a plug-in through the IPublishPlugin interface, which the plug-in must implement. Each selected photo or video file is passed to the plug-in as a stream; metadata can be read through the IPublishProperties interface. Publishing progress can be displayed to the user through the IPublishProgressCallback interface.
When a publishing plug-in is activated, the hosting Windows Live application makes several calls to the plug-in through the IPublishPlugin interface.
ConceptsCommunicating with the Windows Live Photo Gallery Publishing Plug-in Platform
Windows Live Photo Gallery Publishing Plug-in Registry Settings