BDC (Batch Data Communication) is used to import large amounts of data into SAP systems. It works by simulating user input via an ABAP program to ensure data consistency. Data is entered into an internal table with fields for program, screen, cursor position, user commands, and input fields. This table can be created using transaction SHDB for recording. The data is then transferred using either call transaction or BDC sessions. Call transaction runs updates in real-time while BDC sessions allow batch processing of data at a later time.

1. What is BDC
BDC ( Batch Data Communication ) is used for uploading mass data into SAP system. In SAP system BDC also referred to batch input or
data tranfer.
Typical Uses
Typical uses of batch input include the one-time import of data from a legacy system into a newly installed R/3 System. Another typical
use is for periodic transfers of data from external systems or legacy systems that are still in use into SAP.
Background of BDC
To ensure data consistency in SAP system, we must not update SAP data directly from ABAP program. We must upload data through
similar program flow compared to manual input by user. SAP provide this by BDC. BDC works by simulating the user input from
transactional screen via an ABAP program. This means that you do not bypass any of the standard SAP consistency checks, authorisations,
update conjunction tables, etc.
How it works
Data input entered by user simulated in BDC by data packet. The transaction then started using this internal table as the input and
executed in the background.
Data packet is an internal table has a structure of BDCDATA, it has fields:
1. PROGRAM (program name)
2. DYNPRO (screen number)
3. DYNBEGIN (New screen start) X=new screen
4. FNAM (Field name)
5. FVAL (Field value)
Data packet contain of screen by screen packets. One screen packet contain:
1. Screen no
2. Cursor position
3. User command
4. Input fields
It implemented in internal table in this format:
PROGRAM DYNPRO DYNBEGIN FNAM FVAL
program1 screen1 X
BDC_CURSOR pos1

2. BDC_OKCODE comm1
fieldname1 fieldvalue1
fieldname2 fieldvalue2
program2 screen2 X
BDC_CURSOR pos1
BDC_OKCODE comm1
fieldname1 fieldvalue1
fieldname2 fieldvalue2
For example, we want to create a BDC to change ABAP program title.
Here is what we do manually: Go to screen SE38, enter program, select radiobutton "Attributes", then click "Change". After that, change
title then press "Save" button.
In BDC, we simulate this by following internal table:
PROGRAM DYNPRO DYNBEGIN FNAM FVAL
SAPLWBABAP 100 X
BDC_CURSOR RS38M-FUNC_HEAD
BDC_OKCODE =CHAP
RS38M-PROGRAMM ZAALTESTBDC
RS38M-FUNC_EDIT
RS38M-FUNC_HEAD X
SAPLSEDTATTR 200 X
BDC_CURSOR RS38M-REPTI
BDC_OKCODE =CONT
RS38M-REPTI Test change title BDC
TRDIR-SUBC 1
TRDIR-FIXPT X
SAPLWBABAP 100 X
BDC_CURSOR RS38M-PROGRAMM
BDC_OKCODE =BACK
RS38M-PROGRAMM ZAALTESTBDC
RS38M-FUNC_HEAD X
To accomodate you to build data packet, SAP provide BDC recording in tcode SHDB.
Do following action:
1. Go to tcode SHDB
2. click "New recording", enter recording name to identified your record, and TCode to be recorded.
3. You will enter recording mode of the transaction, simulate action you want to perform in this transaction
4. At the end it will result internal table ready to upload to data transfer methods (Call transaction or BDC sessions).
After internal table created then we pass this to data transfer methods. There are two alternatives of data transfer methods, using Call
Transaction or BDC session.
Call transaction performed by calling command ‘Call Transaction’. ABAP program must do the error handling based on returning table
from call transaction command. It is used for real-time interfaces and custom error handling & logging features. This is suitable when
processing sequential update, it means, next data will depend on previous data.
In BDC Sessions, the ABAP program creates a session with all the transactional data, and this session can be viewed, scheduled and
processed (using Transaction SM35) at a later time. The latter technique has a built-in error processing mechanism too.