Introduction to Replication Agents

A Replication Agent is an SAP Replication Server client that retrieves information from the transaction log for a primary database and formats it for the primary Replication Server. RepAgent is the Replication Agent component for SAP ASE.

Replication Agent detects changes to primary data and ignores changes to nonprimary data. Using Log Transfer Language (LTL), a subset of Replication Control Language (RCL), Replication Agent sends changes in primary data to the primary SAP Replication Server, which distributes the information to replicate databases.

The Replication Agent connections status is derived from the status of the Replication Agent thread in the SAP Replication Server, and the status of the Replication Agent process that is extracting data from the primary database. You can use SAP® Control Center for Replication to monitor the Replication Agent thread or the Replication Agent process and alert you if any Replication Agent has stopped running.

SAP provides Replication Agent components for other non-SAP ASE data servers, including IBM DB2 Universal Database, Microsoft SQL Server, and Oracle. See the Heterogeneous Replication Guide and the Replication Server Options documentation for the databases actively supported by SAP Replication Server.

Replication Agent for DB2 is the Replication Agent component for the z/OS-based DB2 Universal Database. SAP Replication Agent is the Replication Agent component for DB2 Universal Database (on UNIX and Windows platforms), Microsoft SQL Server, and Oracle.

RepAgent is an SAP ASE thread. Replication Agent for DB2 is a separate process that resides on the z/OS host. SAP Replication Agent is a separate application that resides on a UNIX or Windows host.

A Replication Agent:

Logs in to the SAP Replication Server.
Sends a connect source command to identify the session as a log transfer source and to specify the database for which transaction information will be transferred.
Gets the name of the maintenance user for the database from the SAP Replication Server. RepAgent filters out operations executed by the maintenance user, unless the send_maint_xacts_to_replicate or send_warm_standby_xacts configuration parameter is set to true.
Requests the secondary truncation point for the database from the SAP Replication Server. This returns a value, called the "origin queue ID", that RepAgent uses to find the location in the transaction log where it is to begin transferring transaction operations. The SAP Replication Server has already received operations up to this location.
Retrieves records from the transaction log, beginning at the record following the secondary truncation point, and formats the information into LTL commands.

Format of the Origin Queue ID
The origin queue ID is a unique 32-byte binary string that increases in value as each new log record is transferred. The value must increase, because Replication Server ignores records with an ID lower than the highest ID stored in the inbound queue.
Replication Agent Products
Replication Agent products extend the capabilities of SAP Replication Server by allowing non-SAP database servers to serve as primary database servers in an SAP replication system.
SAP Replication Server and LTL Compatibility
Replication Agents and SAP Replication Server negotiate the version of LTL to use for the session. This ensures that Replication Agents written for earlier versions of SAP Replication Server remain compatible with more recent and current versions.