Defining Protocol Buffer Messages

message Product {
  string sku = 1;
  string name = 2;
  double price = 3;
  bool in_stock = 4;
}

message UpdateUserRequest {
  string id = 1;
  optional string email = 2;     // can distinguish "not set" from ""
  optional int32 age = 3;
}

message Cart {
  repeated string product_ids = 1;
  repeated LineItem items = 2;        // [packed=true] is default for scalars
}

message Order {
  message LineItem {
    string sku = 1;
    int32 qty = 2;
  }
  repeated LineItem items = 1;
}
// Referenced externally as Order.LineItem

enum OrderStatus {
  ORDER_STATUS_UNSPECIFIED = 0;   // MUST be 0
  ORDER_STATUS_PENDING = 1;
  ORDER_STATUS_PAID = 2;
  ORDER_STATUS_SHIPPED = 3;
  ORDER_STATUS_CANCELED = 4;
}

message User {
  reserved 2, 5, 9 to 11;
  reserved "legacy_token", "old_email";
  string id = 1;
  string email = 3;
}

message Request {
  map<string, string> headers = 1;
  map<int32, Product> products_by_id = 2;
}

message Notification {
  string user_id = 1;
  oneof channel {
    EmailPayload email = 2;
    SmsPayload sms = 3;
    PushPayload push = 4;
  }
}

syntax = "proto3";
package user.v1;

import "google/protobuf/timestamp.proto";
import "common/v1/address.proto";

message User {
  string id = 1;
  google.protobuf.Timestamp created_at = 2;
  common.v1.Address address = 3;
}