following up from my prior thread https://answers.sap.com/questions/276665/analysis-options-required-customer-task-provider-f.html and with respect to Resmi's Blog https://archive.sap.com/documents/docs/DOC-53315:
I've created a basic and, by now, working configuration for the implementation of a Custom Task Provider on a Gateway System, ultimately for visualition within the standard App Fiori My Inbox 2.0. The backbone for that implementation is a facade class inheriting from /IWPGW/CL_TGW_TASK_FACADE_ABS, as per official Documentation. After doing a bit more research into which methods are what for, I've come around the topic "Backend Operation Proxy" (BOP). To be brief: The major recommendation seems to be, to use a BOP for third party (non-SAP) data providers which provide some kind of API via, let's say, a Webservice.
Now, there is a method CREATE_WS_BOP in the Facade-Class which makes sense to me according to my aforementioned research results. However, there also is a method CREATE_RFC_BOP, I assume, obviously, for RFCs.
What makes me wonder and what I haven't been able to find out yet is, whether there is any situation in which the usage of BOPs is sensible when retrieving data from another SAP System or, put differently, I don't (yet) see any difference between an RFC-BOP from SAP-System A to SAP-System B and a simple Remote CALL FUNCTION, except for X more wrappers around the BOP and the actual RFC-Call.
Deriving from my research results, so far, I would go for a simple CALL FUNCTION and leave the BOPs alone, unless somebody can explain to me that there are advantages to using a BOP instead of a direct RFC-Call that I currently don't know of or have not yet been able to figure out.