Every SAP R/3 screen is called a dialog step which is represented by dynpro. A dynamic program is also called as dynpro, which consists of a screen and all the associated processing logic. A dialog step contains field definitions, screen layout, validation and processing logic…etc. A dialog step is controlled by a dynamic program. The dynamic program’s processing logic controls what has to be done before the screen is displayed (PBO – Process Before Output) and what has to be done after the user completes entering information into the screen fields (PAI – Process After Input).
We are navigating screen to screen in the SAP R/3 system means, actually we are making dialog steps within the R/3 system. A transaction includes a set of dialog steps.
Example: I will explain this by creating an user in the SAP R/3 system. The dialog steps are given below.
- Log-in to SAP R/3 System and enter the transaction code su01 in the command box and hit enter
- You will getUser ‘Maintenance initial screen’ where we have to enter the user name to be created within the SAP R/3 system – One dialog step
- Enter the user name which you planed to create and hit F8
- ‘Main user’ screen will be opened – This is second dialog step
- Enter the details about the user as per your requirement and click SAVE button or Ctrl+S
- You will get the confirmation screen with message of User was saved in the status bar which is located at bottom of the screen – This is Third Dialog step
LUWs – Logical Units of Work
A LUW (Logical Unit of Work) is an elementary processing step, it works as a locking mechanism to protect the integrity of a transaction. That means, there is no possibility of committing the database change simultaneously within the SAP R/3 system using LUW concept. A set of steps within a transaction is called Logical Unit of Work (LUW) and all of these steps must be completed correctly to go ahead with the transaction logic. The current LUW will be canceled, if there are any errors before the end of the transactions, but not the previous ones. There are three conceptually different types of transactions may be distinguished in the SAP R/3 system, They are listed below….
Database LUW: A database LUW is a database transaction is the period of time in which the operations requested must be performed as a unit. This is known in the database world as an all or nothing operation. At the end of the LUW, either the database changes are committed (performed) or they are rolled back (thrown away).
SAP LUW: SAP LUW is an update transaction is the equivalent to the database concept for the SAP systems. This means that as a logical unit, these SAP LUWs are either executed completely or not at all. A SAP LUW can have many database LUWs. The ‘COMMIT WORK’ is a special ABAP command will marks the end of a SAP LUW and the beginning of a new SAP LUW.
SAP transaction: A SAP or ABAP transaction is made up of a set of related tasks combined under one transaction code. This concept is related more to the programming environment, in which an ABAP or SAP transaction functions like a complex object containing screens, menus, programming logic, transaction code, and so forth.