No Internet-wide directory has been made, yet the twenty-first century could use one. The ability to determine reputation, address, trustworthiness, identity, and permissions for the hordes of folk demanding user attention would manage access to data stores and greatly ease transaction completion. Perhaps the best place to begin such an endeavor is creating a corporate identity management architecture. A virtual directory would permit applications to extract data from multiple servers, combining records from various systems and sharing user data between applications. Applications for such directories would be broad, to say the least. Anti-spam appliances could check inbound messages against approved users and reject messages sent to nonexistent addresses. Compliance applications could reference data from e-mail directories and human resources systems to determine authentication levels and message policies. Several such products exist as of 2005. Octet String Inc.'s Java-based Virtual Directory Engine can cross-examine RDBMS, Active Directory, LDAP, or Windows NT servers and apply the results to other applications based on these platforms. Maxware offers virtual directory, metadirectory, synchronization, and identity management products. The Identity Management division of Persistent Systems uses over 30 full-time engineers to provide systems integration work and custom development.