Here is a way of defining a service in SAP R3 in order to then generate a data list with SAP UI5. This way, the new SAP interface can be introduced evolutionarily with the R3 system. If you migrate to S/4 afterwards, the user interface remains the same.
With Netweaver 7.50 and SAP S/4HANA 1909, you can do the whole procedure in eclipse, this is descibed by a SAP Turial "Create an ABAP Core Data Services (CDS) View in SAP NetWeaver 7.5". Unfortunately not for non HANA systems
The older way begins with the data definition in Eclipse (the classic SFlight, an aggregation over the table SBOOK)
The @ OData.publish: true annotation turns the view into an oData service.
This action is not possible in the SE80, but must be carried out in Eclipse in any case.
Here, the view can be checked in advance even without the SAP gateway being set up.
It then continues in Netweaver with the transaction / IWFND / MAINT_SERVICE, the service is added to the service catalog and activated.
The successful activation of the service can also be tested with the browser. The metadata of the oData service is displayed.
Then the front end is created. I am using the Web-IDE Personal Edition and a template for this. The HANA Web-IDE or VS Code is also possible.
The oData connection can be called up immediately if the Netweaver host is set up correctly.
And the template can be tested.
The app appears in the launchpad
And can be called.
Look at the bcount column, that's the number of records I've grouped. The table contains a total of 1.3 million data records.
The application can now be adapted or expanded and then deployed into the test system.
I find it remarkable how quickly and easily such a service can be created and used.
In my opinion, however, the development skills are shifting significantly towards core data and services and front-end development with UI5 / Fiori.