This post serves to outline what you can build in the "Use CAP and SAP Cloud SDK to Extend S/4HANA" mission created for SAP TechEd 2019.
Update Feb 2021: This mission has now been retired as the details relating to the products and topics at hand have moved on; features have changed and improved over the last year and a half.
There are four missions that have been put together specifically for SAP TechEd 2019, covering Cloud Platform Portal, Cloud Platform ABAP Environment, HANA Advanced Analytics, and (my favourite) S/4HANA Extensions with CAP.
The S/4HANA Extensions with CAP mission consists of six tutorials, with some checkpoints in between.
Even after TechEd, the mission is available to you, and you can jump in right now here:
In essence, you use CAP to mock an S/4HANA API, which produces a nice OData v4 service, stick an OData v2 adapter proxy in front of it, try it out manually with the SAP Cloud SDK in the Node.js REPL, then go and build another OData service with CAP that has its own entities but also reaches out to consume the first service (the mocked S/4HANA API) too, using the SAP Cloud SDK in some custom service implementation logic. Finally you add some annotations to drive a simple Fiori elements based app.
To provide you with a map of sorts, for your journey, here's a diagram showing the essential parts of what you'll be building, and how they relate to each other.
Tutorials 1 and 2 concern themselves with the green components (in the middle), tutorials 3, 4 and 5 concern themselves with the blue components (on the left hand side), and tutorial 6 is where you drive the Fiori elements app shown at the bottom.
If you are attending SAP TechEd in Bangalore next week, come on down to the Developer Garage where you can follow this journey yourself on workstations set up for you all to complete the missions.
If you can't make it to SAP TechEd this year, no problem - you can complete this mission at home too!
Good luck, and don't forget to pack a flask of decent coffee before you set off on your journey!