When it comes to integration SAP with third party applications like Moodle, the most important aspect is start with is the SAP version in question. This is so because SAP comes in various flavors, each having its own technology stack and integration capabilities.
For example S4 has completely different architecture as compared to SAP Business One. SAP Business by Design is a SaaS based offering and has its own unique API structure.
If you are looking for some information on the above, you can refer to the SAP integration guide our here. This outlines the integration protocols as well as best practices that you need to keep in mind.
Hope this helps.