Monday, July 26, 2010

LSMW - Legacy System Migration Workbench

                      The Legacy system migration workbench ( LSMW ) is an R/3-based tool that supports single or periodic data transfer from your non-SAP system to R/3 .It is a component of the R/3 System and, therefore, is independent from the platform.

                      The data is loaded via the standard interfaces of the applications.This will include all checks that are run for online transactions. Invalid data will be rejected.

Core Functions of LSMW


Importing legacy data from PC spreadsheet tables or sequential files.
Converting data from its original ( legacy system ) format to the target (R\3) format.
Importing the data using standard interfaces of R\3 ( IDOC inbound processing , batch input , direct input )

Which data can be migrated using LSMW ?


  • By means of standard transfer programs: a wide range of master data (e.g G/L accounts , customer master , vendor master , material master) and transaction data (e.g financial documents , sales order )
  •     By means of recording of transactions: further data objects (if the transaction can be run in batch input mode)













    
The main advantages of the LSMW:

  • 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)

  • 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
Prior to using LSMW, it is recommended to perform some


conceptual tasks.


Process Flow:
 
 


The following should be taken into account:


  • Make sure that the R/3 Customizing has been completed.

  • Analyze the data that exists in your legacy system (LS) and which of it (from a business point of view) will be required in the future as well.
  •  Identify the transaction(s) in the R/3 System that you want to use to transfer the data to this system.
  • Process the respective transaction in R/3 manually using test data of the
  • legacy system and note which fields must be filled. Maybe there are required fields that do not correspond to a data field in the legacy system. In this case, assigning a fixed value or constant or setting up a field as an optional field perhaps is useful for the data transfer .
  • Carry out mapping on paper, that is, allocate the source fields and R/3 fields to each other. You can do this by using the object overview after you defined the object.
  • Determine the conversion rule according to which the field contents of the source fields are to be converted into R/3 fields.
  • Define the way in which the data is to be extracted from the non-SAP system. (The LSMW does not extract any data itself) .
  • Which format does the legacy data have? Decide which standard import technique you want to use, or if you should define an extra "object class” by means of recording.
  • In case only a part of your legacy system is to be replaced with the R/3 System, you have to determine the functions that are to be covered by the R/3 System and those to be covered by the legacy system. If necessary,a concept of the data flows and interface architecture has to be created.
Objects of LSMW

  • Project
  • Sub-project
  • Object
  • Structure Relationship
  • Field - Assignment
 Project

Definition

All the data of an application system that is to be transferred to the SAP R/3 System.

Use

In the LSMW, the project serves as an organizational unit used to combine mapping and field assignments.

Structure

The project consists of:

  • Sub project
  • Business object (object)
  • Structure relationships
  • Field assignments

Integration

A project can have any number of sub projects assigned to it.


Sub-Project

Definition


An organizational unit subordinated to the project.

Integration

A sub project can have any number of objects.

Example

Data migration in a company with several plants in which data is organized in different ways. In this case, the complete migration of data would be the project. The sub projects would comprise the data in the individual plants.

Object
 
Definition


                  An object is a unit combined from the business point of view, which is used to transfer the data of a project to the SAP R/3 System.

Structure

An object consists of the following elements:

  • Tables involved in the project and in the SAP R/3 System
  • Structure(s) for transfer of data
  •  Relationship between data at the table and field level
  • Field assignments for conversion of data.

Integration

                 An object is assigned to a sub project. For example, customer master,material master, or financial documents are objects.

Structure Relationship

Definition


Structure relationships are mappings between structured trees.

Use

                     The mappings between the trees have to make sense. This means, the structures of the data to be migrated (referred to as "source structures" ) have to be created within the hierarchy in a way that they can be allocated to the structures in the R/3 System (referred to as target structures" ).

Field Assignment :

Definition


                                     A collection of rules that define how the field contents are to be onverted during data migration from the legacy system to the SAP R/3 System.

Use

                                 The field assignments use placeholders and conversion rules in order to ensure both flexibility and consistency of data. In migration customizing, you assign values to the placeholders and select the processing types for the conversion rules.

Structure


The field assignments are distinguished by the different levels of reference:

  •         At the highest level, there is the domain, which is defined by the field type, field length, and value tables, or by means of fixed values.
  •        At the second level, there are the data elements, which are defined by the domain as well as by language-dependent texts.
  •      At the lowest level, there are the fields, which are defined by field names and data elements. The field-related rules refer to them.
                                  The placeholders and conversion rules defined by the field assignments are either linked to the target field directly or through the domain.

Example for Batch Upload :

Material master data transfer using LSMW for transaction mm01.

  • Enter the Name for the project, subproject and object and press create button.

                                 As soon as you have create the project, you have to record the transaction,
(ctrl + F2) in this case its going to be mm01.

                                           Once you are through with the recording, maintain the field properties, by double clicking on the 3rd column of any field. This needs to be done for all the fields for which you made an entry during recording. Then go to LSMW, press ctrl + f8 for the corresponding project.


When you are done with maintaining the Object attributes( you have to mention the

name of the recording in Batch Input Recording ), now the next step is to maintain source attributes.

Select No.2 Radio option and Press F8 and in the next screen you have to mention the source structure by clicking create button and then save it.

Go back and by default No.3 Radio option must have been selected, if not select No.3

Radio option “Maintain source field”. In the source field screen, create the field, by pressing ctrl + F3 for all the fields that you made an entry during recording.

Go back and select No.5, “Maintain Field Mapping and conversion rules” and press ctrl F8.
Click Assign Source Field for each field in a structure and map it to the Project structure.

Go back and select No: 7 Radio option “Specify files” , press CTRL F8 , then create entry for Legacy Data, specify the file name and then save it.

Go back and select No:8 radio option “Assign files” and press CTRL F8 , then go to No.9

“Read Data”, execute it and enter the value for no.of transaction(say 1-999999), execute it.

Then Select No:10 “Display read data” to check whether value from .txt file is properly

assigned to the corresponding fields in the structure.

Follow the previous procedure for Step 10-12. Create the Batch Input

Session and Run the Batch input session.


















  • The Legacy System Migration Workbench (LSMW) is a tool that supports data migration from non-SAP systems to the SAP R/3 System. It is a component of the R/3 System.


  • The LSMW supports a one-time transfer of data (initial data load) and also offers a restricted support of permanent interfaces. Thus, a periodic transfer of data is possible. The LSMW, however, does not include any functions for monitoring of permanent interfaces. The tool does not support any data export interfaces (outbound interfaces).

3 comments:

  1. As you can see, the business strategies you made in the present era are not the same as they were when you started your business. Your business requires modernization of the legacy system to save the time and cost of maintenance.
    Your blog post is very useful for my knowledge. Thanks for sharing.
    Legacy System Migration

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