The dispatcher is a program which manages the resources of the R/3 applications. They are very similar to a police dispatcher who receives requests via 911 and routes it to available officers who are in the area.

What is a Dispatcher?

The dispatcher receives requests from the many users on the system and passes them along to the corresponding work processes which are free.  It also manages the information flow between the app server and the SAPGUI.

Each app server has only one dispatcher because it could get kind of difficult for two dispatchers to route requests to the work processes.

To summarize,

• Program which manages resources of the R/3 applications
• Receives requests from user and passes them to the corresponding work processes
• Only one dispatcher per application server

Tasks of Dispatcher

The dispatcher is responsible for balancing the workload between the work processes so that processes don’t sit idle. Memory management is also one of its duties.  The dispatcher must also organize the communication between the work processes and also between the SAPGUI and app server.

•     Balances the workload between the processes
•     Buffer management in main memory
•     Connection with the presentation level
•     Organization of the communication processes

Dispatcher is used to handle the user requests that are coming from SAP GUI using DIAG (Dynamic Information Action Gateway) protocol on port 3200 + Instance Number. Dispatcher manages all the work process and maintains a queue. Once the request is sent to dispatcher the dispatcher keeps the request in queue.