In ECC, whenever we needed to trigger some activities after an SD document has been saved (could be sales or billing document, for example), our options were pretty much limited to (a) a standalone program that would run in a background job and select new/updated documents; (b) an output with special function.
Are there any additional / better options for this in S/4 (specifically 2020)? I haven't heard of any but thought I'd check here if anyone has intel on this.
Bonus question: how would ABAP developers even find such information (new SD features in S/4 relevant to development)? It's not like we can subscribe to "SD news for ABAPers Weekly" magazine...
for Side-By-Side extensions you would have a look at the SAP S/4HANA Business Events on api.sap.com. In this case the Sales Order Events. But to consume them you need BTP Event Mesh and build an event driven architecture.
If you want to consume inside the S/4HANA system you might check the answer to BOR type and event for transaction ABF1. Then implement an Event Handler. An example for such a handler class is CL_SD_SLS_DRF_BOR_HANDLER. The Linkage from the Event to the Class / Method is defined in Transaction SWE2.Hope that helps.Best Regards