work process

Dispatcher
The SAP dispatcher is the control program which manages the resources of the R/3 applications. It workslike a typical transaction monitor which receives screens and data from the presentation services and passes them to the corresponding work processes. 

The various work processes are described briefly below.
Dialog Work Process
Dialog work processes deal with requests from an active user to execute dialog steps.

Update Work Process
Update work processes execute database update requests. Update requests are part of an SAP LUW that bundle the database operations resulting from the dialog in a database LUW for processing in the background.

Background Work Process
Background work processes process programs that can be executed without user interaction (background jobs).

Enqueue Work Process
The enqueue work process administers a lock table in the shared memory area. The lock table contains the logical database locks for the R/3 System and is an important part of the SAP LUW concept. In an R/3 System, you may only have one lock table. You may therefore also only have one application server with enqueue work processes.

Spool Work Process

The spool work process passes sequential datasets to a printer or to optical archiving. Each application server may contain only one spool work process.