User exit classes

For inbound and outbound transactions on a publish channel, an enterprise service, or an invocation channel, a user exit class can have a preprocessor method and a postprocessor method. For inbound transactions, the user exit class can have an extra method that processes business objects just before they are committed to the database.

Preprocessing method for outbound transactions
The input to the first outbound user exit point is the XML that is generated by the object structure. If you have an ERP adapter processing class, you can use either the preprocessing method or postprocessing method to implement your custom logic, depending upon your requirement.
Postprocessing method for outbound transactions
In the postprocessing method of the user exit, the IR element from the object structure and the ER element from the XML output of the processing class are both available for processing.
Preprocessing method for inbound transactions
In the preprocessing method for inbound transactions, the input is the XML message that is delivered from the external system. If necessary, you can change data in the message to affect the processing logic in the processing class.
Postprocessing method for inbound transactions
In the postprocessing method for inbound transactions, both the IR records and ER records are available for processing.
Business object processing on inbound transactions
The user exit class on an enterprise service has an additional method, setUserMboIn, that enables custom processing at the point when the business objects are created from object structure XML, but are not yet saved to the database.