To connect to a SAP instance for sending/receiving data you have various options:

• Remote Function Call (RFC)
• SOAP Webservice
• OData Interface (via SAP Netweaver Gateway)
• Own implemented Webservice via SICF handler class
• …

All of these options have advantages and disadvantages:

• RFC needs a binary library (librfc)
• SOAP Webservices have a huge overhead which I wanted to avoid
• OData was too slow for my use case
• I did not want to implement an own webservice handler class (focus on core aspects of the projects)

So there was no easy to use/fast interface for my actual project available. After some research I’ve sumbled accross the project JSON Adapter for ABAP Function Modules which is exactly what I need: a fast and easy to use interface to my Function Modules.

After I’ve impoerted the code (via SAPLINK), enabled the service in SICF, created the authorization object I was able to use the Function Module outside of the SAP server via HTTPS.

The project I am creating is written in Java and I used the great library Retrofit to consume the webservices. After just a few minutes I was able to consume the Function Module from our SAP server via Java without any overhead (librfc/SOAP generated classes).