OpenAPIs with S4/HANA and Callable

From SAP ECC 6.0 to S4/Hana

S4/HANA is SAP’s next-generation ERP platform built on SAP’s own in-memory technology SAP Hana. While there are many similarities to SAP’s “traditional” SAP ECC 6.0 ERP Suite, there are also new options for implementing business processes and extensions on S4/HANA.

S4/HANA Deployment options

There are 3 major deployment options for S4/HANA:

  • On-premises / Bring your own License
  • Public cloud vendor / Bring your own License
  • Managed Cloud by SAP

The operational model between these variants shifts depending on the chosen model. With on-premises, you are responsible for the infrastructure up to the application level. With public cloud, you manage the software environment and the application level, but not the infrastructure.

With the SAP Managed Cloud offering, you are just using the software and let SAP manage everything from the infrastructure up to the application level.

The major difference in both options is who is responsible for the operations of your S4/HANA Instance. Either you let SAP manage that (Managed Cloud) or you run S4/HANA in your data center or your virtual private cloud (e.g. AWS VPC) by yourself.

Extending S4/HANA On-premises

So what are the major differences to extending SAP ECC 6.0 to S4/HANA and how does Callable come into play?

Callable as a platform targets building Open APIs in a simple, quick and cost-effective way. These APIs can be used to connect external partners, systems of engagement hosted in your cloud VPC or any other integrated process.

While S4/HANA has some new internal techniques to implement business logic more close to SAP’s HANA core technology (Code Pushdown and CDS Views), technically S4/HANA on-premises still offers all the integration options as an SAP ECC 6.0 which are:

  • IDocs
  • BAPIs & RFCs
  • SOAP Services
  • Odata Services

As Callable’s foundation for an API layer are BAPIs / RFCs not much has changed technically to SAP ECC 6.0, let’s have a look at how the official recommended extension options work.

UI vs Service API

There has been a big effort on SAP’s side to provide more “standard” OData services with S4/HANA which is attributed also to its investment into backing Fiori UI Services.

SAP’s strategic extension option on the UI Layer is so-called “in-app extensibility” with its Fiori and Odata Stack. This addresses extensions of UI driven business logic.

SAP’s strategic extension option on the Business Logic / Service API layer is the so-called “side-by-side extensibility” for SAP’s own (java based) Cloud or by partners/other vendors (a good reading resource is “S4/HANA extensibility” released on SAP press) While SAP focuses here on their own S4/HANA SDK for these tasks, also any platform can connect side-by-side extensibility by that way.


Side by Side extensibility with Callable.

Callable makes this “side-by-side” extension option much more simple than building it up “from scratch” as Java app or with SAP’s own cloud.

You could provide widely understood Open APIs directly as a side by side extension for S4/HANA On-premises with the following advantages

  • Plug & Play into the existing BAPI/RFC layer for business application logic
  • No Java app development/deployment & maintenance needed
  • Pay per use model
  • Fully API control already included (throughput control, security & Logging)



As we see “not much” has changed how to provide secure and cost-effective APIs with Callable from SAP ECC 6.0 to S4/HANA on Premise or self-managed on your cloud provider like AWS.

From our experience cutting through SAP and many of its partners’ marketing noise is not easy for most day-day IT departments, decision makers or solution architects. We hope this blog can clear much of the fog what options exist.

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