// task 2 // 1. OpenAPI + gRPC // (YAML) // info: // title: Book API // version: .. // paths: // /books: // get: // responses: // "200"

OpenAPI is a specification for describing REST APIs, usually in YAML or JSON format. It describes paths (endpoints), HTTP methods, parameters, responses, etc.

gRPC is a framework for remote procedure calls (RPC), using Protocol Buffers for data serialization and HTTP/2 for transport.

Example of using OpenAPI to describe a REST API:

openapi: 3.0.0
info:
  title: Book API
  version: 1.0.0
paths:
  /books:
    get:
      summary: Get list of books
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: array
                items:
                  type: object
                  properties:
                    id:
                      type: integer
                    title:
                      type: string

For gRPC, a .proto file is used, for example:

syntax = "proto3";

service BookService {
  rpc GetBooks (Empty) returns (BooksResponse);
}

message Empty {}

message Book {
  int32 id = 1;
  string title = 2;
}

message BooksResponse {
  repeated Book books = 1;
}

Thus, OpenAPI and gRPC are different approaches to describing and implementing APIs: REST with OpenAPI and RPC with gRPC.