Web AS ABAP Components


This post deals with SAP Web AS ABAP components (SAP Web Application Server). Apart from discussing configuration levels of SAP R/3 system, we have also discussed different types of SAP Work processes, SAP dispatcher and minimum number of work processes required in SAP. 


What are the different layers of SAP R/3 system ?

There are three layers of SAP R/3:
(1) Presentation Layer
(2) Application Layer
(3) Database layer


What are the different level of configurations of SAP R/3 system ?

Configurations are based on the number of hosts used. These levels are single-tier, two-tier, three-tier or multi-tier.

In single-tier configuration, all processes (i.e. presentation process, application process and database process) run on the same host.
In two-tier configuration, database and application processes run on one host where as front-end (i.e. presentation process) runs separately.
In three-tier configuration, presentation, application and database processes each run on separate hosts.
In multi-tier configuration, internet webserver is also used along with presentation, application and database servers.


Name the various work processes in Web AS ABAP ?

Work processes are:

(1) Dialog Work process
(2) Background Work process
(3) Spool Work process
(4) Update Work process
(5) Enqueue Work process


What is a dispatcher ?

Dispatcher is a process present on every application server in a SAP System. The responsibility of dispatcher is to assign user requests to a proper work process for its processing.

If the request is for execution of dialog steps then dialog work process is assigned.

If there is a request to execute a program or report in background, then a background work process is assigned.

Spool work process is needed when printing related tasks need to be performed.

Update work process is required to update entries in database tables and enqueue work process is responsible for administration of lock table.



Minimum number of work processes required in SAP ?

Minimum number of Work processes required:
(1) Dialog: 2 per instance
(2) Background: 2 per system
(3) Spool: 1 per system
(4) Enqueue: 1 per system (more than 1 may create trouble)
(5) Update 1 (V1): 1 per system
(6) Update 2 (V2): optional

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