The early versions of R/3, SAP has been providing batch interfacing techniques. Among these techniques, Batch Data Communication (BDC) is the oldest one. BDC is not bi-directional; it is an integration tool in its typical form. It can only be used for uploading data into RJ3. BDC works through an ABAP program and works on the principle of simulating user input for transactional screen.
The purpose of the Batch Data Communication is to transfer data. The BDC can transfer data from one SAP System to another SAP System or can transfer data from non-SAP System to SAP System too. To transfer data BDC uses normal transaction codes. Two methods are provided to BDC to do this work.
SAP has provided two different types of methods for BDC to do its work. Among these, the first one is called the classical method or session method. Through this method the data can be read by the BDC program from a sequential dataset file. This sequential dataset file is stored in batch-input session. In order to .run the transaction in this session, what one needs is to execute the session. For this, follow these few steps: you can start and subsequently monitor the session firstly from – System à Services à Batch Input or have the session run in the background. In this method to generate the required session, you have to use the function module BDC _ NSERT and BDC _CLOSE.
In the second method the BDC has to use the ABAP statement CALL TRANSACTION USING statement to run a transaction. In the second method, unlike in the first type, you do not need BDC to create a session.