Overview

Universal Connector commands are processed by calling appropriate BAPI functions in the SAP system. The BAPI function calls are issued over an RFC connection. Universal Connector provides fault tolerance at the RFC level. If an RFC call fails, the call is retried until it completes successfully or exceeds a user-definable retry limit.

If an RFC call fails, Universal Connector will close the current RFC connection and establish a new RFC connection in order to continue processing. The process of establishing and preparing an RFC connection is referred to here as the RFC logon process. The RFC logon process involves establishing an RFC connection, logging on to the XMI interface and setting the XMI audit level. If the RFC logon process fails, it will be retried until it completes successfully, or exceeds a user definable retry limit. When the new RFC connection is established successfully, Universal Connector will reissue the failed RFC call.

The entire process of establishing a new RFC session and reissuing the failed RFC call will be retried until either:

• RFC call completes successfully.
• User-definable RFC retry limit is exceeded.

Some BAPI functions should not be retried in an unknown state; they are points of failure within the Universal Connector fault tolerant solution.

Points of Failure, below, lists the points of failure and their relationship to Universal Connector commands.

Points of Failure

The points of failure within Universal Connector fault tolerant architecture are:

• Job Submission
• Job Modification
• Job Start

Some BAPI functions called in these processes cannot be restarted in an unknown state without possible negative consequences. If an RFC call fails issuing those BAPIs, Universal Connector will end unsuccessfully.

Network Fault Tolerance Configuration Parameters

The following set of Universal Connector configuration options can be used to fine-tune the fault tolerance support for a particular environment:

• LISTEN_INTERVAL (-rfc_listen_interval)
• LOGON_RETRY_COUNT (-rfc_logon_retry_count)
• LOGON_RETRY_INTERVAL (-rfc_logon_retry_interval)
• SECURE_CFT (-rfc_retry_count)
• RETRY_CALL_INTERVAL (-rfc_retry_interval)
• TIMEOUT_INTERVAL (-rfc_timeout)

See RFC (Remote Function Call) Options for details concerning the use of these parameters.