kratos-service-layer

Service Layer Role

Connects transport (gRPC/HTTP) to business logic:

Responsibilities:

• Handle gRPC/HTTP requests
• Map proto DTOs to business models (via mapper)
• Call use case methods
• Map results back to proto responses
• Convert business errors to gRPC status codes

Service Struct Pattern

type {Entity}Service struct {
	pb.Unimplemented{Entity}ServiceServer  // Embed unimplemented server
	uc biz.{Entity}UseCase                // Use case dependency
}

Handler Method Pattern

func (s *{Entity}Service) Create{Entity}(ctx context.Context, in *pb.Request) (*pb.Response, error) {
	// 1. Map request to business model
	entity := {Entity}FromRequest(in)

	// 2. Call use case
	result, err := s.uc.Create{Entity}(ctx, entity)
	if err != nil {
		return nil, toServiceError(err)  // Map business error to gRPC error
	}

	// 3. Map result to response
	return &pb.Response{Entity: toProto{Entity}(result)}, nil
}