File System driver creates a virtual device with application-provided file system and emulates a physical storage.
The driver works on the system level and turns a storage into a "real" disk device with it's own file system. The "real disk device" is accessible in read-only and/or read-write mode by any application which uses system file management API.

The driver lets you make the mounted disk visible to the user or hide it from the user.
Unlike CallbackDisk, the driver of Callback File System provides a functionality to create not just your virtual disks, but your own file systems. The driver provides a callback mechanism, which lets you keep your files and file systems wherever you want (i.e. on remote computer, in memory or database tables etc.).

User-mode API is simple and introduces about ten functions, specific to driver management and storage mounting operations. Also the API includes about 20 callback functions (events) which your application must handle to effectively represent a full-featured file system.
The API is needed only for driver and storage manipulation. All file operations can be performed using system file management API or framework-specific classes.

User-mode API is provided as a .NET component for .NET Framework development, a static library with one class for use in C++ and a VCL component for use in Delphi.

Major security Features

1. Expose the virtual disk to the user by assigning it a drive letter/ you can keep the virtual disk hidden from user's eye (when no drive letter is assigned).
2. Callback File System lets you control what applications or users access the data.
3. You can support NTFS security functions for files and directories stored within Callback File System.