SAP ABAP BDC AND LSMW COMPARISION

Batch Data Communication (BDC) is the oldest batch interfacing technique that SAP provided since the early versions of R/3. BDC is not a
typical integration tool, in the sense that, it can be only be used for uploading data into R/3 and so it is not bi-directional.
BDC works on the principle of simulating user input for transactional screen, via an ABAP program. Typically the input comes in the form
of a flat file. The ABAP program reads this file and formats the input data screen by screen into an internal table (BDCDATA). The
transaction is then started using this internal table as the input and executed in the background.

In Call Transaction・ the transactions are triggered at the time of processing itself and so the ABAP program must do the error handling.
It can also be used for real-time interfaces and custom error handling & logging features. Whereas in Batch Input 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.

Batch Input (BI) programs still use the classical BDC approach but doesnt require an ABAP program to be written to format the
BDCDATA. The user has to format the data using predefined structures and store it in a flat file. The BI program then reads this and
invokes the transaction mentioned in the header record of the file.

Direct Input (DI) programs work exactly similar to BI programs. But the only difference is, instead of processing screens they validate
fields and directly load the data into tables using standard function modules. For this reason, DI programs are much faster (RMDATIND - Material Master DI program works at least 5 times faster) than the BDC counterpart and so ideally suited for loading large volume data. DI programs are
not available for all application areas.


LSMW is an encapsulated data transfer tool. It can provide the same functionality as BDC infact much more but when coming to techinical perspective most the parameters are encapulated. To listout some of the differences :

LSMW is basicaly designed for a fuctional consultant who do not do much coding but need to explore the fuctionality while BDC is designed for a technical consultant.

LSMW offers different techinque for migrating data: Direct input ,BAPI,Idoc,Batch input recording. While bdc basically uses recording.

LSMW mapping is done by SAP while in BDC we have to do it explicitly .

LSMW is basically for standard SAP application while bdc basically for customized application.

Coding can be done flexibly in BDC when compared to LSMW.



BDC and LSMW are the two data migration techniques (from legacy to SAP) . BDC technique is usually done by ABAPers. It consists of three methods.
1) Call Dialog Method
2) Session Method
3) Call Transaction Method


In the case of Session Method , a BDC Session is created , which has the data and info to run it in batch mode. When the user runs this session, every transactions are run in batch mode and tables are updated.
WHile in call transaction, no session is created. Instead , a report prog is created , which takes input from the file and calls the transaction in Batch mode.

Call dialog method is similar to call transaction, except that updation is done by the calling program itself.This method is obsolete.


Advantages of Batch Input Method are
1)Can process large data volumes
2) data integrity is maintained


LSMW and BDC are vastly different.
BDC (Batch Data Communication) is a technology used for data transfer. it is meant for transferring data thru SAP transactions itself. when u use BDC for data transfer, the sequence of steps is the same as when u use standard sap transaction screens for data upload. the only difference is that u can use different options for foreground/backgrou nd processing.

LSMW on the other hand is a tool that helps migrate data from a legacy system (non-sap system ) to SAP system. it offers u various options to use either batch input, direct input, BAPIs or idocs. it involves a series of some 17-18 steps to migrate data.

BDC:
Batch Data Communication (BDC) is the process of transferring data from one SAP System to another SAP system or from a non-SAP system to SAP System.

Features :
BDC is an automatic procedure.
This method is used to transfer large amount of data that is available in electronic medium.
BDC can be used primarily when installing the SAP system and when transferring data from a legacy system (external system).
BDC uses normal transaction codes to transfer data.

Types of BDC :
CLASSICAL BATCH INPUT (Session Method)
CALL TRANSACTION

BATCH INPUT METHOD:
This method is also called as ‘CLASSICAL METHOD’.
Features:
Asynchronous processing.
Synchronous Processing in database update.
Transfer data for more than one transaction.
Batch input processing log will be generated.
During processing, no transaction is started until the previous transaction has been written to the database.

CALL TRANSACTION METHOD :
This is another method to transfer data from the legacy system.

Features:
Synchronous processing. The system performs a database commit immediately before and after the CALL TRANSACTION USING statement.
Updating the database can be either synchronous or asynchronous. The program specifies the update type.
Transfer data for a single transaction.
Transfers data for a sequence of dialog screens.
No batch input processing log is generated.

LSMW:

The LSM Workbench is an R/3-based tool that supports You when transferring data from non-SAP systems ("Legacy Systems") to R/3 once or periodically.
The tool supports conversion of data of the legacy system in a convenient way. The data can then be imported into the R/3 system via batch input, direct input, BAPIs or IDocs.
Furthermore, the LSM Workbench provides a recording function that allows to generate a "data migration object" in an entry or change transaction.

The main advantages of the LSM Workbench:
• Part of R/3 and thus independent of individual platforms
• A variety of technical possibilities of data conversion:
• Data consistency due to standard import techniques:
Batch input
Direct input
BAPIs (Business Application Programming Interfaces)
IDocs (Intermediate Documents)
The import technique to be used in an individual case depends on the business object.
• Generation of the conversion program on the basis of defined rules
• Clear interactive process guide
• Interface for data in spreadsheet format
• Creation of data migration objects on the basis of recorded transactions
• Charge-free for SAP customers and SAP partners