Bdc and lsmw

Question

Hi All,
I am presuming that both bdc's and lsmw are being used for data migration. if this is right then when would someone prefer bdc over lsmw or vice versa. if my assumption is wrong then tell me for what specifications we use lsmw and for what specs we use a bdc.

Answer 1

Hi,
"The Data Transfer Workbench (or DX Workbench, transaction SXDA) is an integrated SAP tool that supports data transfer and analysis. It
does not have the built-in features for mapping for source structures to target structures, but it will allow you to integrate Legacy System Migration Workbench (LSMW) objects as processing tasks within a run definition. The DX workbench has many features for creating
test data and performing data migrations - for example, logging of data migration runs.
However, if you need to map or convert data, you should use the LSMW. Or, you can integrate
your LSMW objects as task within a more user-friendly data migration run, in which the LSMW
project steps "Read data", "Convert data," and "Start IDoc processing" are automated
and use the features of both tools. If you donot need logging and automated data migration
runs, you can perform your data migration without the DX Workbench."
The following was taken at this site :
http://www.info-sun.com/docs/wp_sapinter.pdf
“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 doesn’t 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.
Remote Function Call (RFC) in SAP R/3 is based on UNIX’s Remote Procedure Call (RPC). RFC enables the real-time link between different R/3 instances and can connect SAP to Non-SAP systems. With Remote Function Call, both inbound (RFCServer) and outbound (RFCClient) interfaces are possible.
SAP also provides a toolkit called RFC API for non-SAP systems to interact with SAP’s Function modules remotely.
RFC is a very powerful tool for interfacing with SAP system in real time. Most other interfacing techniques like ALE, EDI, BAPI etc… are
inherently based on the RFC technology.
Electronic Data Interchange (EDI) is the industry standard format for exchanging Business data. SAP uses a neutral format called Intermediate Document
(IDoc) for communicating EDI & ALE messages.
The IDoc interface contains data structures and processing logic for each of the business transaction. These are grouped as Message
Types. The external EDI Server is responsible for receiving the EDI messages sent by the trading partners. These EDI messages are then
mapped onto the IDoc structure fields and stored in the IDoc interface layer by SAP.
EDI/IDoc supports both inbound and outbound interfaces. The IDocs received through the EDI Server can be configured to automatically get
processed, or can be stored in the IDoc interface layer for a future manual or scheduled processing. The IDoc interface layer also has a powerful error
handling, reporting, monitoring and reprocessingmechanism built into it (Transaction WEDI). IDoc is also tightly integrated with the WorkFlow system
of SAP for initiating other business tasks upon receiving/sending EDI messages.
The IDoc interface can be employed for non-SAP applications to load or extract data from SAP system. But typically, EDI / IDoc is engaged when
SAP system is to be integrated with any of its business partners (Customers, Suppliers and other partners) for carrying out standard business
transactions (like Create Sales orders, Sending Purchase orders to Suppliers, etc…).
Application Link Enabling (ALE) is a middleware tool, which is part of SAP’s Business framework Architecture (BFA). ALE can effectively be used
for loosely coupled Asynchronous communication between SAP systems and with non-SAP systems. ALE is based on the distributed processing
architecture and hence integrates applications with the local database rather than centralized one. ALE messages are based on the Intermediate
Document (IDoc) format, similar to the EDI counterpart. Though ALE can be used to interface with non-SAP systems, usually it is used to
distribute Master & Transactional data between SAP R/3 instances.
The ALE distribution can be based on,
• Business APIs
• IDoc Message Types"
Business API (BAPI) is the most important component of SAP Business Framework. BAPI enables SAP and third party applications to interact and integrate
with each other at the Business Object / Process level.