Property System
In Windows Vista, metadata takes center stage as a method of organizing items such as your files, e-mail, or contacts. In order to enable a system where items can be searched based on their metadata and where users can read or write that metadata, Windows Vista introduces a new property system. Metadata in this system is represented by an extensible set of properties implemented as name/value pairs.
Windows Vista includes an extensive set of properties that cover the specifics of items such as photos, music, documents, messages, contacts, and files. Independent software vendors (ISVs) can introduce their own properties to the platform if no existing property meets their needs.
In this set of topics, we often use the generic term items. We do this because Microsoft Windows presents different storage systems such as file systems, MAPI stores for e-mail, and File Transfer Protocol (FTP) servers through an abstraction layer. Items that you see in a Windows Explorer window or as the result of a search can be true files in the file system or may be coming from a database such as a MAPI store.
In this set of topics we restrict our discussion to file in the file system and describe how you can create a handler that reads and writes properties to and from a file stream. These handlers are called property handlers and each is associated with a given file types, identified by the file name extension. Windows Vista includes property handlers for some common file types including OLEDOC files such as .doc and .ppt; image files such as .jpg and .tiff; and audio/video files such as .mp3, .wma, and .wmv.
The following topics discuss the requirements and strategies involved in defining your properties and property handlers.