SAP R/3 Architecture
Real time 3 tier Architecture
Presentation Layer – Client System
Dispatcher - It is component which takes the request for client systems and stores the request in queue.
Queue – A place where request are stored temporarily.
Dialog Service – It is responsible for performing the I/O operations and also the calculation.
Enqueue Service – Used for placing the locks and releasing the locks on the object to maintain consistency of data.
Update Service – It is used for managing the statement like in INSERT UPDATE DELETE & SELECT.
BG Service – It is responsible for managing the background job, which does not require user interaction.
Special Services – Used for interacting with external devices like printer machine, fax, mail server etc.
Message Service – It is used for managing the communicator between two SAP servers or between SAP and Non-SAP server.
ABAP Workbench – It is a set of tools which contains an environment for developing the objects.