SAP Logon GUI process:

• Once a user clicks on the SAP system from GUI, the user request is forward to Dispatcher.

• Request is stored in Request queues first. Dispatcher follows First in First out rule. It will find free work process and if available, it will be assign.

• As per user request, particular work process is assign to user. For example, when user login to the system then Dialog work process is assign to the user. If user runs a report in background then background work process will be assign to the user. So as per user's action work process is assigned. Actually, the dispatcher makes contact with message server of the central instance so that it can announce available work processes to the user request and allocate the available work processes to it.

• Once user is assign the dialog work process then user authorizations, user's current setting are rolled in to work-process in shared memory to access user's data. Once dialog step executed then user's data rolled out from work process. Thus, memory be cleaned and other user's data can be saved in shared memory area.

• 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 improved and this process is called hit ratio. 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.

• Now, if it does not find the data in buffer then it will fetch data from database and send the data to GUI through dispatcher.

• As the user’s data removed from shared memory the available, free memory be used by some others user’s request. This is Roll-out