On Sun, Jul 2, 2017 at 12:07 PM, Phil Endecott via Boost <boost@lists.boost.org> wrote:
Do any of the Beast examples show its use in asynchronous mode?
The files marked "async_*" and also multi_port.hpp use asynchronous interfaces: https://github.com/vinniefalco/Beast/tree/78a065ba39836d91d7e70d93de7f9140f5... The use of Beast's asynchronous HTTP interfaces is virtually identical to Asio's.: http://www.boost.org/doc/libs/1_64_0/doc/html/boost_asio/reference/use_futur... Replace `my_socket.async_read_some` with `beast::http::async_read` and adjust parameters. Beast uses Asio's extensible asynchronous model so however you receive notifications when your asynchronous Asio task completes, will also work with asynchronous HTTP function signatures. The documentation explains some of the return value customization (its written from the perspective <http://vinniefalco.github.io/beast/beast/using_networking/writing_composed_operations.html>
I'm wondering how difficult it is to achieve this:
future< vector< byte > > data = download(url);
I won't candy-coat this: You're going to have to do some heavy lifting. The `download` function is going to have to first do everything necessary to establish the connection, using direct Asio interfaces. If you want "https://" support you will need to write that too. In fact, you better bring a URL parser if you want the ship to leave the launch pad. Once you have your socket established you'll have to fill out a beast::http::request with the correct information and then call beast::http::async_write to send it to the remote host. You'll need to take care of proxy settings if any, as well as Basic Authentication if the server requires it. If the remote host redirects you then you'll have to handle that yourself too. To make it work with futures, you will need to implement all of this in the style of a "composed operation" which requires significant boilerplate and expertise. Beast provides classes, functions, examples, and a tutorial of this style to help you get it going: <http://vinniefalco.github.io/beast/beast/using_networking/writing_composed_operations.html> The signature for your initiating function will look like this: template<class CompletionToken> beast::async_result< CompletionToken, void(error_code, std::vector<char>)> async_download( beast::string_view url; CompletionToken&& token); You would call it this way: std::future<vector<char>> result = async_download("http://www.example.com/", boost::asio::use_future); Hope this helps! Thanks