File Watcher notifies you when interesting things happen in the file system. What kinds of things? File and folder creation, deletion, moving, and renaming. (If we can find any more activities we'll add those, but that's all HFS supports at this time.)
File Watcher comes in several pieces: an extension (which includes necessary patches), a faceless background app, and a demo app (with freely reusable source code). In development are additional apps that use File Watcher's capabilities to provide system administrators with useful information.
The extension and FBA are ready-to-run, simply drop them in the Sytem Folder.
File Watcher supports two notification mechanisms which you can use in your products. The callback interface requires that you register a callback function with the FBA. The Apple Event interface requires that you register handlers with the Apple Event Manager. Both mechanisms support unregistering (an important action to take!)