SAP USER REQUEST WORKFLOW

USER REQUEST WORKFLOW:

1)      User request using SAP GUI to communicate with SAP Application Server.

The user request is carried by DIAG (Dynamic Information Action Gateway) protocol.

2)      Dispatcher on the Application Server receives the user request and keep them in queue (dispatcher wait queue)

3)      Based on the available free work process dispatcher allocates work process to handle the user requests on FIFO (first in first out)

4)      Work process has Task handler to process the user request.

5)      Task handler consist of 3 interpreters:

a)      Screen Interpreter: It is used to interpret the screen in the user request

b)      ABAP Interpreter: It is used to interpret ABAP code in the user request

                   c)  SQL Interpreter: It is used to interpret SQL code and SQL statements

6)      If the request is accessed earlier and the context is available in buffer. It is                          fetched from or the request is saved from buffers.

7)      If the content is accessed for the first time , it is converted OPEN SQL to NATIVE SQL of the database using DB client (DBSL library).

8)      The request goes to database and handover the task to database processes.

9)      Database process handles the request and sends the response back to the work process.

10)   R/3 work process checks, if the response is eligible for buffering & store a copy in R/3 buffer.

11)  The response is re-interpreted to sent it back to the user.

12)  Buffer sending the response it is stored in user context.

13)  User context is only accessed by the user (himself) and it is available till the user session. If user log off the user context is no more.

USER CONTEXT:

It is a memory area it contains user related information such as user authentication, authorizations, parameters, earlier access screens.

User context remains until user session. If the session is terminated or user logged off user context will no more available.

TASK SCENARIO:

1)      User request to display last week sales report.

2)      User request goes to dispatcher and sits in queue

3)      Dispatcher allocates work process based on FIFO and available work process.

4)      Work process roll-in user context into task handler

5)      Work process interprets the user request

6)      Checks whether the user request response is available in R/3 buffer.

7)      If available sends the response back to the user ( roll-out user context)

8)      If the context is not available convert the request to native sql request and communicate with database to process user request

9)      Database sends the response back; eligible content is stored in R/3 buffers.

10)  The response is send to the user before it roll-out to user context.

Roll-out:

     The process of rolling out (save in the user related information) user specific info into memory (user context) its termed as roll-out.

Roll-in:

          The process of copying the user related information into work process task handler (TSKH) is referred as roll-in.

OPEN SQL statement:

                                SAP uses OPEN SQL in ABAP programs.

This is ensuring that the programs are independent of database.

NATIVE SQL:  This is the language used by database

Ex: oracle user’s pl/sql, Microsoft uses T-sql

The usage of OPEN SQL has the following advantages:

1)      R/3 becomes database independent.

2)      Optimal utilization of R/3 buffers avoids complete  database times

3)      Using native sql increases performance for the first records where as open sql had bad response time initially but later considerably improved by using R/3 buffers.

4)      Open sql user R/3 locking mechanism to handle SAP transaction.