I put together a diagram describing the inter-process communication in AWA v12.2, based on the Server Processes documentation page.
I'm not sure the diagonal line between the AWI and the JCP is correct. Does the AWI talk directly to the JCP?
In a comment, Robert Thullner confirmed that the AWI does communicate directly with the JCP for some functions:
[T]he AWI only uses the REST API partly, as not all functionality is available via the REST API yet. The communication between AWI and the backend is still mainly via the Java API.
I believe that each CP has communication to the AE DB directly
Yes, that is my understanding. I would have to run a trace with srvquery=1 in the AE ini to be sure but that is the only function I could see using something other than the MQ tables.
I now see that you have a bullet point for this and I think that is sufficient for not adding extra clutter to the diagram.
to my best knowledge:
Well, each UC4 Server Process has a connection to the database, regardless of the Server Process Type.
A CP will mainly work with MQ tables, however it uses other tables than MQ* as well. Think about the various settings in client 0, which needs to be read by a CP as well. I think the DIVDB tables is used as well by a CP, etc.