The gRPC protocol (https://grpc.io/) is used to support the transport layer between the Axxon One services. 

The gRPC API allows to simplify the large-scale systems configuration.

The gRPC protocol uses special proto-files to generate the code base.

The proto-files contain some strict syntax that defines the interface for the various program modules interaction.

You can call gRPC API methods using a POST request (see gRPC API method calls) or through direct gRPC requests (see 직접 gRPC 요청을 통해 Axxon One과 작업).