Method call

src/IO/ReadWriteBufferFromHTTP.h:107–152

        std::function<void(size_t)> next_callback;

        std::istream * call(Poco::URI uri_, Poco::Net::HTTPResponse & response)
        {
            // With empty path poco will send "POST  HTTP/1.1" its bug.
            if (uri_.getPath().empty())
                uri_.setPath("/");

            Poco::Net::HTTPRequest request(method, uri_.getPathAndQuery(), Poco::Net::HTTPRequest::HTTP_1_1);
            request.setHost(uri_.getHost()); // use original, not resolved host name in header

            if (out_stream_callback)
                request.setChunkedTransferEncoding(true);

            for (auto & http_header_entry: http_header_entries)
            {
                request.set(std::get<0>(http_header_entry), std::get<1>(http_header_entry));
            }

            if (!credentials.getUsername().empty())
                credentials.authenticate(request);

            LOG_TRACE((&Poco::Logger::get("ReadWriteBufferFromHTTP")), "Sending request to {}", uri_.toString());

            auto sess = session->getSession();

            try
            {
                auto & stream_out = sess->sendRequest(request);

                if (out_stream_callback)
                    out_stream_callback(stream_out);

                istr = receiveResponse(*sess, request, response, true);
                response.getCookies(cookies);

                content_encoding = response.get("Content-Encoding", "");
                return istr;

            }
            catch (const Poco::Exception & e)
            {
                /// We use session data storage as storage for exception text
                /// Depend on it we can deduce to reconnect session or reresolve session host
                sess->attachSessionData(e.message());
                throw;
            }
        }

    public:
        using NextCallback = std::function<void(size_t)>;