This section is a detailed guide to the RTA API, Toolkit Services and their gRPC APIs.
Have you read the Introduction?
Start there to review the archictecture and key concepts.
The RTA API is the external-facing API consumed by ATLAS. This is designed to be an interface on the edge of your data environment — so you can exploit ATLAS capabilities without copying your data or making big changes to your data pipeline.
The Toolkit Services provide implementations of the API, in either a single-process or microservices architecture. They expose GPRC APIs to read, write and manage their data stores — but these are specific to these services and not part of the RTA API Specification.
This means the services in the implementation toolkit are entirely optional, and a seamless integration should be achievable in any convenient framework by implementing only the necessary parts of the RTA API.