In the context of an SAP CRM landscape, Middleware refers to the R3 adapter, which is used to transfer data from the CRM to external systems such as R3, mobile client, Groupware and vice versa. The data are sent via qRFC (queued remote function calls). The Middleware is also used to transfer data internally from CRM Online to the CDB.
Types of Data Transfer/Loads using Middleware:
(i) Initial load (can be from R3 to CRM or CRM to R3).
(ii) Delta load (only from R3 to CRM)
(iii) Upload (only from CRM to R3)
(iv) Request (uses the same framework as the initial load)
Important Transactions for Analysing MW Issues:
R3AS: Start Initial load
R3AC1: Adapter Object Overview (Application Objects)
R3AC3: Adapter Object Overview (Customizing Objects)
R3AC5: Adapter Object Overview (Condition Objects)
768503 Documentation for CRM Administration
765236 FAQ: Queueing in CRM and R/3