Microservices in C++: Architecture, Practice, and Code Examples

Introduction to Microservices in C++

Microservice architecture (MSA) is one of the dominant approaches to building modern distributed systems. Despite the fact that C++ is less commonly associated with microservices than Go, Java or Python, it remains indispensable for scenarios where performance, low latency, and efficient memory usage are critical. In this article, we will examine how to build microservices in C++, which frameworks and libraries to use, and look at practical code examples.

Why C++ for Microservices?

The main advantages of C++ when developing microservices:

• Maximum performance — C++ allows achieving minimal response time (latency) and high throughput.
• Resource control — manual memory management and optimization at the hardware level.
• Mature libraries — Boost, Poco, cpp-httplib, gRPC, Crow.
• Integration with legacy systems — C++ is often used in the cores of high-load systems (finance, telecom, gaming).

Microservice Architecture in C++

Main Components

A typical microservice in C++ includes:

• HTTP/REST server — for receiving requests (for example, using cpp-httplib or Crow).
• Business logic — data processing modules.
• Client for inter-service communication — gRPC or HTTP client.
• Working with storage — connecting to PostgreSQL, Redis or Kafka via libraries (libpqxx, redis-plus-plus, librdkafka).

Communication Between Services

Two main protocols:

• gRPC — binary protocol based on Protobuf, provides strict typing and high speed.
• REST (JSON) — convenient for external APIs, but slower due to serialization.

Practice: Creating a Microservice in C++

1. Simple REST API using cpp-httplib

Let's look at a minimal service that accepts a GET request and returns JSON. The cpp-httplib library is header-only and easy to include.

// main.cpp#include <httplib.h>#include <nlohmann/json.hpp>

using json = nlohmann::json;

int main() {    httplib::Server svr;

    // GET /hello — returns JSON    svr.Get("/hello", [](const httplib::Request& req, httplib::Response& res) {        json response;        response["message"] = "Hello from C++ microservice!";        response["status"] = "ok";        res.set_content(response.dump(), "application/json");    });

    // POST /data — accepts JSON and processes it    svr.Post("/data", [](const httplib::Request& req, httplib::Response& res) {        try {            auto input = json::parse(req.body);            int value = input["value"];            json result;            result["squared"] = value * value;            res.set_content(result.dump(), "application/json");        } catch (const std::exception& e) {            res.status = 400;            res.set_content("{\\"error\\":\\"Invalid JSON\\"}", "application/json");        }    });

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

Build (requires nlohmann/json installed):

g++ -std=c++17 main.cpp -o microservice -lpthread./microservice

2. Microservice with gRPC

gRPC requires defining the service in a .proto file. Example:

// calculator.protosyntax = "proto3";

service Calculator {    rpc Add (AddRequest) returns (AddResponse);}

message AddRequest {    int32 a = 1;    int32 b = 2;}