Vehicle.proto

package com.example;

/**
 * Represents a manufacturer of cars.
 */
message Manufacturer {
    /**
     * Manufacturer category. A manufacturer may be either inhouse or external.
     */
    enum Category {
       CATEGORY_INHOUSE = 0;  /** The manufacturer is inhouse. */
       CATEGORY_EXTERNAL = 1; /** The manufacturer is external. */
    }

    required int32 id = 1;          /** The unique manufacturer ID. */
    required string code = 2;       /** A manufacturer code, e.g. "DKL4P". */
    required Category category = 3; /** Manufacturer category. */
    optional string details = 4;    /** Manufacturer details (minimum orders et.c.). */
}

/**
 * Represents a vehicle model.
 */
message Model {
    required string id = 1;         /** The unique model ID. */
    required string model_code = 2; /** The car model code, e.g. "PZ003". */
    required string model_name = 3; /** The car model name, e.g. "Z3". */

    required sint32 daily_hire_rate_dollars = 4; /// Dollars per day.
    required sint32 daily_hire_rate_cents = 5;   /// Cents per day.
}

/**
 * Represents a vehicle that can be hired.
 */
message Vehicle {
    /**
     * Represents a vehicle category. E.g. "Sedan" or "Truck".
     */
    message Category {
        required string code = 1;        /// Category code. E.g. "S".
        required string description = 2; /// Category name. E.g. "Sedan".
    }

    required int32 id = 1;          /** Unique vehicle ID. */
    required Model model = 2;       /** Vehicle model. */
    required string reg_number = 3; /** Vehicle registration number. */
    optional sint32 mileage = 4;    /** Current vehicle mileage, if known. */
    optional Category category = 5; /** Vehicle category. */

    // Doc comments for fields can come before or
    // after the field definition. And just like
    // comments for messages / enums, they can be
    // multi-paragraph:

    /**
     * Dollars per day.
     *
     * Taken from model if unspecified.
     */
    optional sint32 daily_hire_rate_dollars = 6;

    /**
     * Cents per day.
     *
     * Taken from model if unspecified.
     */
    optional sint32 daily_hire_rate_cents = 7;
}