Possible way of integration oatpp with other I/O engines.
Simple example how to use oatpp REST framework by "manually"
substituting Request object.
// Process request in oatpp by
// manually substituting what you have received from your IO engine
oatpp::String body = "Hello World!!!";
oatpp::web::protocol::http::Headers headers;
headers["Content-Length"] = oatpp::utils::conversion::int32ToStr(body->getSize());
auto response = Utils::processRequest("POST", "/body", router, headers, body);
// Take resultant response and send it back
oatpp::data::stream::ChunkedBuffer downstream;
response->send(&downstream);
oatpp::String responseText = downstream.toString();
OATPP_LOGD("Example", "downstream:\n%s", responseText->getData());