This is another random post which serves no purpose other than highlight another bit of interesting SAP related trivia. One fine friday afternoon with little work, I was navigating around SM51 in one of our internal test servers. In ‘Goto’->’Server Information’->’Queue Information’ I noticed a few queues, one for each process type. One of them was NOWP, the other process types neatly map on to the different work process types. What the heck could NOWP mean? The F1 help had me more confused –NOWP Queue for requests for which no work process is required, but which are processed or forwarded by the dispatcher itself.
Googling a bit led me to this excellent post in which SAP_Basis_Chap discusses the NOWP process type and gives a good overview on the kinds of requests which are handled by the dispatcher itself(and hence no work process is required) and why these kinds of requests vastly outnumber the others.
Quoting the knowledgeable SAP_Basis_Chap,
The dispatcher loops through the queues and sends the tasks to the various work processors for action. Now the dispatcher also needs to do its own tasks and other little jobs like for example the following :
A dispatcher sees a logon request in the NOWP queue and checks the users authorization and password to log on (SAPSYS in client 000).
It then adds a logon screen request to the DIA WP queue and when it loops around to the time to dispatch tasks to the DIA WP it will send the request off.
The WP then does what is required to process the request and sends the information for the gui into a memory area (WP_CA without checking) and adds a request into the NOWP queue that the info needs sending back to the user.
The dispatcher loops around to processing its NOWP queue and sends the data in the WP_CA area off to the GUI or whatever. You can appreciate that the dispatcher is rather busy in a system and if you look at the statistics in the NOWP queue in SM51 you will see it does a lot more work than anyone else.
Very interesting; trivia such as this are wonderful. To me they give an insight and an idea of the architecture of ABAP stack along with a greater appreciation towards the meticulous software engineering that went into its design.