Home » C++ » Boost.ASIO-based HTTP client library (like libcurl) [closed]

Boost.ASIO-based HTTP client library (like libcurl) [closed]

Posted by: admin November 30, 2017 Leave a comment

Questions:

I am looking for a modern C++ HTTP library because libcurl’s shortcomings are difficult to work around by C++ wrappers. Solutions based on Boost.ASIO, which has become the de-facto C++ TCP library, are preferred.

Answers:

The other day somebody recommended this on another thread:

http://cpp-netlib.github.com/

I think this is as high-level as you will find, but I’m not sure if it’s mature enough yet (I would say it probably is since they’ve proposed it for Boost inclusion).

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Better late than never, here’s a new answer to an old question. There’s this new open source library called Boost.Beast which offers both HTTP and WebSocket functionality using Boost.Asio. It emulates the familiar Asio interfaces as closely as possible, and its got plenty of documentation. It builds on clang, gcc, and Visual Studio using either bjam or CMake – your choice! Note, I am also the author of the library.

https://github.com/boostorg/beast/

Here’s a complete example program that retrieves a web page:

#include <boost/beast/core.hpp>
#include <boost/beast/http.hpp>
#include <boost/beast/version.hpp>
#include <boost/asio/connect.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <cstdlib>
#include <iostream>
#include <string>

using tcp = boost::asio::ip::tcp;       // from <boost/asio/ip/tcp.hpp>
namespace http = boost::beast::http;    // from <boost/beast/http.hpp>

// Performs an HTTP GET and prints the response
int main(int argc, char** argv)
{
    try
    {
        // Check command line arguments.
        if(argc != 4 && argc != 5)
        {
            std::cerr <<
                "Usage: http-client-sync <host> <port> <target> [<HTTP version: 1.0 or 1.1(default)>]\n" <<
                "Example:\n" <<
                "    http-client-sync www.example.com 80 /\n" <<
                "    http-client-sync www.example.com 80 / 1.0\n";
            return EXIT_FAILURE;
        }
        auto const host = argv[1];
        auto const port = argv[2];
        auto const target = argv[3];
        int version = argc == 5 && !std::strcmp("1.0", argv[4]) ? 10 : 11;

        // The io_context is required for all I/O
        boost::asio::io_context ioc;

        // These objects perform our I/O
        tcp::resolver resolver{ioc};
        tcp::socket socket{ioc};

        // Look up the domain name
        auto const results = resolver.resolve(host, port);

        // Make the connection on the IP address we get from a lookup
        boost::asio::connect(socket, results.begin(), results.end());

        // Set up an HTTP GET request message
        http::request<http::string_body> req{http::verb::get, target, version};
        req.set(http::field::host, host);
        req.set(http::field::user_agent, BOOST_BEAST_VERSION_STRING);

        // Send the HTTP request to the remote host
        http::write(socket, req);

        // This buffer is used for reading and must be persisted
        boost::beast::flat_buffer buffer;

        // Declare a container to hold the response
        http::response<http::dynamic_body> res;

        // Receive the HTTP response
        http::read(socket, buffer, res);

        // Write the message to standard out
        std::cout << res << std::endl;

        // Gracefully close the socket
        boost::system::error_code ec;
        socket.shutdown(tcp::socket::shutdown_both, ec);

        // not_connected happens sometimes
        // so don't bother reporting it.
        //
        if(ec && ec != boost::system::errc::not_connected)
            throw boost::system::system_error{ec};

        // If we get here then the connection is closed gracefully
    }
    catch(std::exception const& e)
    {
        std::cerr << "Error: " << e.what() << std::endl;
        return EXIT_FAILURE;
    }
    return EXIT_SUCCESS;
}

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asio author implement:

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You should also check out the Pion Network Library:

http://pion.org/projects/pion-network-library

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Boost.Http – a new player here: https://github.com/BoostGSoC14/boost.http, docs – http://boostgsoc14.github.io/boost.http/

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There’s this project trying to “Boostify” libcurl: https://github.com/breese/trial.url

I’ll use this as a reference to design Boost.Http client API. However, I plan to focus on high-level abstractions and try to collaborate as much as possible with Beast.HTTP author.