Legato & API usage

depened on what exactly you mean

exchange:
For traditional backups, the primary operation Microsoft Exchange
Server supports is a database backup. A database backup uses the
Exchange Backup API to save the database files and manage the
transaction log files. The NetWorker Module provides the
mechanism that integrates the Exchange database backup technology
with NetWorker software features.

rsm:
The NetWorker software interacts with Removable Storage systems through an
application programming interface (API). Support for this API is installed as a
standard component during NetWorker server or storage node setup.
Use of Removable Storage is optional. You can disable Removable Storage, for
example, so that NetWorker software can have exclusive use of a library. If this is the
case, disregard this chapter and follow the procedures in Chapter 11, ”Device
Operations.”

SQL:
The NetWorker XBSA API translates the object names requested by the
NetWorker Module for Microsoft SQL Server into a format the NetWorker
software understands, and forwards them to the NetWorker server nsrd service.
After the media is mounted, the nsrmmd program sends the data through the
NetWorker XBSA API to nsrsqlrc, which recovers the data to the Microsoft SQL
Server directories.