How to communicate between services — gRPC, REST, or something else?

The choice of communication method between services depends on requirements for performance, compatibility, and development convenience.

• REST — the most common approach, uses HTTP and JSON. Easy to implement and debug, suitable for public APIs and when compatibility with various clients is important.

• gRPC — based on HTTP/2 and Protocol Buffers, provides high performance and compact messages. Suitable for internal microservice interactions where speed and strict typing are crucial.

• Message Brokers (e.g., Kafka, RabbitMQ) — for asynchronous message exchange, when reliability and scalability are needed.

Example of using gRPC in Go:

// Service definition in proto
service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply);
}

// Server implementation
func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
  return &pb.HelloReply{Message: "Hello " + in.Name}, nil
}

The choice depends on specific tasks and the project infrastructure.