As a primary data server, Microsoft SQL Server interacts with Replication Agent. The Replication Agent must be installed on Microsoft Windows and must have direct access to the Microsoft SQL database log.
The Replication Agent identifies and transfers information about data-changing operations or transactions from a Microsoft SQL Server primary database to a primary Replication Server.
The Replication Agent interacts with the primary Replication Server and with the RSSD of the primary Replication Server, if so configured.