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userver

userver is the modern open source asynchronous framework with a rich set of abstractions for fast and comfortable creation of C++ microservices, services and utilities.

documentation > Community

How It Works

The problem of efficient I/O interactions is solved transparently for the developers

πŸ™ userver 

std::size_t Ins(storages::postgres::Transaction& tr,
                std::string_view key) {
  auto res = tr.Execute("INSERT INTO keys VALUES ($1)", key);
  return res.RowsAffected();
}
Classic C++
template <class OnSuccess>
void Ins(storages::postgres::Transaction& tr,
         std::string_view key, OnSuccess&& on_success) {
  tr.Execute("INSERT INTO keys VALUES ($1)", key,
    [on_success = std::forward<OnSuccess>(on_success)]
    (const auto& res, const auto& error) {
      if (error) {
        report_error(error);
        return;
      }
      on_success(res.RowsAffected());
    }
  );
}

Values of userver

Technologies for debugging and memory profiling a running production service

Write your first toy C++ service, evolve it into a production ready service.

Efficient asynchronous drivers for databases (MongoDB, PostgreSQL, MySQL/MariaDB, Valkey, Redis, ClickHouse, YDB, SQLite ...) and data transfer protocols (HTTP, WebSockets, gRPC, TCP, AMQP-0.9.1, Apache Kafka, ...), tasks construction and cancellation.

Functionality to change the service configuration on-the-fly. Adjust options of the deadline propagation, timeouts, congestion-control without a restart.

Rich set of high-level components for caches, tasks, distributed locking, logging, tracing, statistics, metrics, JSON/YAML/BSON.

Comprehensive set of asynchronous low-level synchronization primitives and OS abstractions.

Service Example

Simple πŸ™ userver service that handles HTTP requests to "/kv" URL and responds with a key from database 


#include <userver/easy.hpp>
#include "schemas/key_value.hpp"

int main(int argc, char* argv[]) {
    using namespace userver;

    easy::HttpWith<easy::PgDep>(argc, argv)
        // Handles multiple HTTP requests to `/kv` URL concurrently
        .Get("/kv", [](formats::json::Value request_json, const easy::PgDep& dep) {
            // JSON parser and serializer are generated from JSON schema by userver
            auto key = request_json.As<schemas::KeyRequest>().key;

            // Asynchronous execution of the SQL query in transaction. Current thread
            // handles other requests while the response from the DB is being received:
            auto res = dep.pg().Execute(
                storages::postgres::ClusterHostType::kSlave,
                // Query is converted into a prepared statement. Subsequent requests
                // send only parameters in a binary form and meta information is
                // discarded on the DB side, significantly saving network bandwidth.
                "SELECT value FROM key_value_table WHERE key=$1", key
            );

            schemas::KeyValue response{key, res[0][0].As<std::string>()};
            return formats::json::ValueBuilder{response}.ExtractValue();
        });
}

Brands and companies using userver