Connecting to Poloniex Push-API

Question

I want to connect to the Push API of Poloniex. On their page they write the following:

In order to use the push API, connect to wss://api.poloniex.com and subscribe to the desired feed.

wss = WebSocket Secure -> SSL Protected

They also give an example for Node.js and Autobahn|JS:

var autobahn = require('autobahn');
var wsuri = "wss://api.poloniex.com";
var connection = new autobahn.Connection({
  url: wsuri,
  realm: "realm1"
});

connection.onopen = function (session) {
        function marketEvent (args,kwargs) {
                console.log(args);
        }
        function tickerEvent (args,kwargs) {
                console.log(args);
        }
        function trollboxEvent (args,kwargs) {
                console.log(args);
        }
        session.subscribe('BTC_XMR', marketEvent);
        session.subscribe('ticker', tickerEvent);
        session.subscribe('trollbox', trollboxEvent);
}

connection.onclose = function () {
  console.log("Websocket connection closed");
}

connection.open();

However, I do not want to use JavaScript, instead I use C++. There's also a Autobahn-Library for C++, called Autobahn|CPP. I've installed it and tried to run their subscriber example code with little modifications (basically just hardcoded the adress and port):

#include <autobahn/autobahn.hpp>
#include <boost/asio.hpp>
#include <iostream>
#include <memory>
#include <tuple>

void topic1(const autobahn::wamp_event& event)
{
    std::cerr << "received event: " << event.argument<uint64_t>(0) << std::endl;
}
using namespace boost;
using namespace boost::asio;
using namespace boost::asio::ip;
int main()
{
    try {

        boost::asio::io_service io;
        boost::asio::ip::tcp::socket socket(io);

        bool debug = true;
        auto session = std::make_shared<
                autobahn::wamp_session<boost::asio::ip::tcp::socket,
                boost::asio::ip::tcp::socket>>(io, socket, socket, debug);

        boost::future<void> start_future;
        boost::future<void> join_future;

        boost::asio::ip::tcp::endpoint rawsocket_endpoint( boost::asio::ip::address::from_string("173.236.42.218"), 443/*8000=standard*/);


        socket.async_connect(rawsocket_endpoint,
            [&](boost::system::error_code ec) {
                if (!ec) {
                    std::cerr << "connected to server" << std::endl;

                    start_future = session->start().then([&](boost::future<bool> started) {
                        if (started.get()) {
                            std::cerr << "session started" << std::endl;
                            join_future = session->join("realm1").then([&](boost::future<uint64_t> s) {
                                std::cerr << "joined realm: " << s.get() << std::endl;
                                session->subscribe("ticker", &topic1);
                            });
                        } else {
                            std::cerr << "failed to start session" << std::endl;
                            io.stop();
                        }
                    });
                } else {
                    std::cerr << "connect failed: " << ec.message() << std::endl;
                    io.stop();
                }
            }
        );

        std::cerr << "starting io service" << std::endl;
        io.run();
        std::cerr << "stopped io service" << std::endl;
    }
    catch (std::exception& e) {
        std::cerr << e.what() << std::endl;
        return 1;
    }

    return 0;
}

There are a few things to explain here: I found out the IP-Adress 173.236.42.218 by simply pinging api.poloniex.com.

Port 443 is the standard SSL-Port. I've tried using the standard WAMP/WebSocket port which is 8000, but the server does not accept that. 80 is also not accepted.

So if I start the program, the output is the following:

starting io service

connected to server

Then, nothing happens. So the code must be stuck at session_start(), where the WS handshake is performed, what you can see when you look into wamp_session.ipp at line 80.

In my opinion the problem is that the API wants to use a secure connection (wss://). It seems like this piece of code does not try to create a SSL-encrypted connection and I don't know how to tell the session that I need a secure one.

Edit: In this question the Author says that Autobahn can't handle mixed http/wamp servers where and upgrade http-request is required first before using the WebSocket protocol. I know Poloniex uses such a mixed type, but I've tried to access the API with Autobahn|JS already and there it works fine, also sending the upgrade request. So maybe this is a Autobahn|CPP issue?

Edit 2: If the above is true, is it possible to send the Http-Update-Request myself and maybe even put a SSL-encryption onto the connection? I'm not sure because maybe that would interfere the library.

Answer 1

No, no, no this is a late response. Late or not though, I believe it may be a bit more direct a solution for you Bobface (and any others that struggled with this). I hesitate to give this out, as it will potentially be used by competitors. But, what's life without competition!? Boring, that's what. And moreover, I wish someone had come before me and posted this, so here you go! Be the change you wish to see, right?

Below, you'll find an implementation utilizing websocketpp and autobahn|cpp to connect to Poloniex's push api. In this case, it will receive updates made to the books for BTC_ETH.

Generally speaking, this is how you can utilize websocketpp and autobahn|cpp to connect to a secure web socket server implementing WAMP protocol (aka something like wss://ip-address.com:port).

Cheers!

Includes:

#include <autobahn/autobahn.hpp>
#include <autobahn/wamp_websocketpp_websocket_transport.hpp>
#include <websocketpp/config/asio_no_tls_client.hpp>
#include <websocketpp/client.hpp>
#include <boost/version.hpp>
#include <iostream>
#include <memory>
#include <string>
#include <tuple>

Code:

typedef websocketpp::client<websocketpp::config::asio_tls_client> client;
typedef autobahn::wamp_websocketpp_websocket_transport<websocketpp::config::asio_tls_client> websocket_transport;

try {
    //std::cerr << "Connecting to realm: " << parameters->realm() << std::endl;

    boost::asio::io_service io;
    //bool debug = parameters->debug();

    client ws_client;
    ws_client.init_asio(&io);
    ws_client.set_tls_init_handler([&](websocketpp::connection_hdl) {
        return websocketpp::lib::make_shared<boost::asio::ssl::context>(boost::asio::ssl::context::tlsv12_client);
    });
    auto transport = std::make_shared < autobahn::wamp_websocketpp_websocket_transport<websocketpp::config::asio_tls_client> >(
            ws_client, "wss://api.poloniex.com:443", true);

    // create a WAMP session that talks WAMP-RawSocket over TCP
    auto session = std::make_shared<autobahn::wamp_session>(io, true);

    transport->attach(std::static_pointer_cast<autobahn::wamp_transport_handler>(session));

    // Make sure the continuation futures we use do not run out of scope prematurely.
    // Since we are only using one thread here this can cause the io service to block
    // as a future generated by a continuation will block waiting for its promise to be
    // fulfilled when it goes out of scope. This would prevent the session from receiving
    // responses from the router.
    boost::future<void> connect_future;
    boost::future<void> start_future;
    boost::future<void> join_future;
    boost::future<void> subscribe_future;
    connect_future = transport->connect().then([&](boost::future<void> connected) {
        try {
            connected.get();
        } catch (const std::exception& e) {
            std::cerr << e.what() << std::endl;
            io.stop();
            return;
        }

        std::cerr << "transport connected" << std::endl;

        start_future = session->start().then([&](boost::future<void> started) {
            try {
                started.get();
            } catch (const std::exception& e) {
                std::cerr << e.what() << std::endl;
                io.stop();
                return;
            }

            std::cerr << "session started" << std::endl;

            join_future = session->join("realm1").then([&](boost::future<uint64_t> joined) {
                try {
                    std::cerr << "joined realm: " << joined.get() << std::endl;
                } catch (const std::exception& e) {
                    std::cerr << e.what() << std::endl;
                    io.stop();
                    return;
                }

                subscribe_future = session->subscribe("BTC_ETH", &on_topic1).then([&] (boost::future<autobahn::wamp_subscription> subscribed)
                {
                    try {
                        std::cerr << "subscribed to topic: " << subscribed.get().id() << std::endl;
                    }
                    catch (const std::exception& e) {
                        std::cerr << e.what() << std::endl;
                        io.stop();
                        return;
                    }

                });
            });
        });
    });

    std::cerr << "starting io service" << std::endl;
    io.run();
    std::cerr << "stopped io service" << std::endl;
}
catch (std::exception& e) {
    std::cerr << "exception: " << e.what() << std::endl;
    ret_var.successfully_ran = false;
    return ret_var;
}

Answer 2

I know this is a rather late response to your question, but it appears the problem is you are not performing the HTTP/Websocket upgrade upon connecting to the remote server. The example code you are using is setup with the rawsocket_endpoint transport, which my guess means the there is no HTTP Websocket upgrade or Websocket encapsulation occurring. I do not believe your problem has anything to do with SSL.

To get Websocket connections to work you should review the AutobahnCPP example that makes use of Websocketpp.