Microservices in C++: Architecture and Practice for High-Load Systems

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Introduction: Why C++ for Microservices?

Microservice architecture has firmly entered the world of development, but is traditionally associated with languages like Go, Java, or Python. However, C++ remains indispensable where performance, low latency, and efficient memory usage are critical. In this article, we will analyze how to build microservices in C++, which libraries to use, and how to organize the infrastructure.

Main advantages of C++ in microservices:

Maximum performance (natively compiled code)
Minimal memory consumption
Full control over resources
No garbage collector (predictable latency)

We will examine architecture, REST API implementation, gRPC, working with queues, and containerization using practical examples.

Microservice Architecture in C++

Basic Principles

A microservice in C++ should be:

Autonomous — each service works independently
Loosely coupled — minimal dependencies between services
Business-function oriented — one service solves one task
Fault-tolerant — graceful degradation

Typical Project Structure

my_microservice/├── CMakeLists.txt├── src/│   ├── main.cpp│   ├── server/│   │   ├── http_server.cpp│   │   └── http_server.h│   ├── service/│   │   ├── order_service.cpp│   │   └── order_service.h│   ├── repository/│   │   ├── order_repository.cpp│   │   └── order_repository.h│   └── config/│       ├── config.cpp│       └── config.h├── include/│   └── (public headers)├── tests/│   └── test_order_service.cpp└── Dockerfile

Practical Implementation: REST API Microservice

Choosing an HTTP Library

For C++, the best options are cpp-httplib (lightweight, header-only) and Drogon (full-featured framework). Let's look at an example with cpp-httplib.

Example: Order Management Service

// main.cpp#include <httplib.h>#include <nlohmann/json.hpp>#include <iostream>#include <memory>#include "order_service.h"

using json = nlohmann::json;

int main() {    httplib::Server svr;    auto orderService = std::make_shared<OrderService>();

    // POST /orders — create order    svr.Post("/orders", [orderService](const httplib::Request& req, httplib::Response& res) {        try {            auto data = json::parse(req.body);            auto order = orderService->createOrder(data);            res.set_content(order.dump(), "application/json");            res.status = 201;        } catch (const std::exception& e) {            res.set_content(json{{"error", e.what()}}.dump(), "application/json");            res.status = 400;        }    });

    // GET /orders/{id} — get order    svr.Get(R"(/orders/(\\d+))", [orderService](const httplib::Request& req, httplib::Response& res) {        int orderId = std::stoi(req.matches[1]);        auto order = orderService->getOrder(orderId);        if (order) {            res.set_content(order->dump(), "application/json");        } else {            res.status = 404;            res.set_content(json{{"error", "Order not found"}}.dump(), "application/json");        }    });

    std::cout << "Server started on port 8080" << std::endl;    svr.listen("0.0.0.0", 8080);    return 0;}

// order_service.cpp#include "order_service.h"#include <stdexcept>

using json = nlohmann::json;

json OrderService::createOrder(const json& data) {    if (!data.contains("product_id") || !data.contains("quantity")) {        throw std::invalid_argument("Missing required fields");    }

    Order or