I don't know the internals of SAP. I really don't have to. For us, SAP is a collection of OLAP cubes that have a highly curated view of that part of the business that the SAP system manages.
And there's a clean API to this data since SAP supports the XML/A SOAP interface standard to those OLAP cubes. It is a very chatty API to extract the data from the cube - but it gets the job done. It allows us to leverage all of the business logic that goes into the cube schema, and the huge investment that the business makes in SAP. I could instead run extracts of the underlying source data but that would lack all of the business logic that goes into the cube definition. I do occasionally have to use their desktop UI to better understand the cube schemas. It is like a trip down memory lane to use the SAP user interface screens. Harks back to the 90s for sure.
Anyway, if anyone's interested in interfacing with SAP through a relatively clean programmatic interface, I highly recommend using the XML/A soap interface to the cubes. My client company's SAP team does a great job of building cubes that expose what is relevant to the business. The SAP data is merged with lots of other business data in our data warehouse and the business gets a modern web and Tableau reports. Problem solved.
