SAP_R3_ARCHITURE

 

SAP Architecture is defined as a technology framework of SAP system and it changes with time from software version to version.

SAP Architecture changes with new software like SAP ECC 6.0, the most recent one.

 

Database: collection of data in organized tables. With database can do

                                                                                   storage of data in tables.

                                                                                    creation of new tables

                                                                                    Accessed data

                                                                                    Modification of new tables/data

                                                                                    Delete of tables/data.

Application server: where all the logic of code resides.

 

Presentation layer: frontend for Application layer.

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Drawbacks:                                                                                                                                                   
There is No Q- mechanism.                                                                                               

R/3 Client/Server Architecture:                                                                                                           

               

                                                                                                     

                                                            Fig: Single Application server architecture.            

 Buffer:   it will store frequently access data and rarely modified data.

suppose based on the RAM( buffer) size in application server, it can  store 100 recent requests, say like RAM size is 8 GiB.

when the complete new request came from end user say 101 request, Buffers will automatically delete 1 st request in 100 requests and include this 101 request in to the 100 request back.So the buffer memory is filled with 100 requests again.

 

Dual stack Application architeuture:

 

Step 1) Once a user clicks on the SAP system from GUI, the user request is forwarded to Dispatcher.
Step 2) Request is stored in Request queues first. Dispatcher follows First in First out rule. It will find free work process and if available will be assigned.

Step 3) As per user request, particular work process is assigned to user. For example, when user login to the system then Dialog work process is assigned to the user. If user runs a report in background then background work process is assigned to the user.When some modifications are done at database level then update workprocess is assigned.So as per user's action work process is assigned.

 

Work processor: 16

dialog wp – 10
background work process – 3
spool workprocess – 1 – print

Update 1 – 1 – data base update
update 2 – 1 – statics of update wp 1 à like percentage the update work process1  done(ex:10---20 %)




Step 4) Once user is assigned the dialog workprocess then user authorizations, user's current setting are rolled in to work-process in shared memory to access user's data.  Once dialog step is executed then user's data is rolled out from workprocess. Thus shared memory will be cleaned and other user's data can be saved in shared memory area. Dialog step means the screen movements. In a transaction, when a users jumps from one screen to other the process is called a dialog step.

Step 5) First work process will find the data in the buffer. If it finds data in buffer then there is no need to retrieve data from database. Thus response time is improved and this process is called Buffer hit. If it does not find the data in buffer then it will find the data in database and this process is called miss. Hit ratio should be always higher than miss ratio. It improves the performance of system .

Step 6) Other requested data is queried from the database and once the process is complete,the result is sent back to GUI via dispatcher.

Step 7) At the end user's data is removed from shared memory so the memory will be available to other users.This process is called roll-out.

Message server functionality:

Message server – purpose of message server is to load balancer the user traffic.                

 

 

1 st request for 1 st application  - 10: 00 AM

2^nd request for 2^nd application

in case of 500 requests    – 250 requsts 1^st application server
                                            250 requsts 2^nd application server

 

SAP landscape:

DEV – DB               - laptop 1
DEV  - Applicatioon   - laptop 2
DEV – Presentation .

Quality – DB              - Laptop 3
Quality – Appplication – Laptop 4
Quality - presentation layer

Production – DB                - laptop 5
Production – Appplication   - laptop 6
production presentation layer

Good references:
https://www.guru99.com/learning-sap-architecture.html