Refactor all examples:

fix #575, fix #604, fix #608, fix #634, fix #712

All examples are rewritten:

* Using Best Practices
* Mostly self-contained
* New examples to complete the feature matrix
* The server-framework example is removed

example/http/server/async/CMakeLists.txt

@@ -0,0 +1,19 @@
+#
+# Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+#
+# Distributed under the Boost Software License, Version 1.0. (See accompanying
+# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#
+# Official repository: https://github.com/boostorg/beast
+#
+
+GroupSources(include/boost/beast beast)
+GroupSources(example/common common)
+GroupSources(example/http/server/async "/")
+
+add_executable (http-server-async
+    ${BOOST_BEAST_INCLUDES}
+    ${PROJECT_SOURCE_DIR}/example/common/write_msg.hpp
+    Jamfile
+    http_server_async.cpp
+)

example/http/server/async/Jamfile

@@ -0,0 +1,15 @@
+#
+# Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+#
+# Distributed under the Boost Software License, Version 1.0. (See accompanying
+# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#
+# Official repository: https://github.com/boostorg/beast
+#
+
+exe http-server-async :
+    http_server_async.cpp
+    :
+    <variant>coverage:<build>no
+    <variant>ubasan:<build>no
+    ;

example/http/server/async/http_server_async.cpp

@@ -0,0 +1,451 @@
+//
+// Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Official repository: https://github.com/boostorg/beast
+//
+
+//------------------------------------------------------------------------------
+//
+// Example: HTTP server, asynchronous
+//
+//------------------------------------------------------------------------------
+
+#include "example/common/write_msg.hpp"
+
+#include <boost/beast/core.hpp>
+#include <boost/beast/http.hpp>
+#include <boost/beast/version.hpp>
+#include <boost/asio/ip/tcp.hpp>
+#include <boost/asio/strand.hpp>
+#include <boost/config.hpp>
+#include <algorithm>
+#include <cstdlib>
+#include <functional>
+#include <iostream>
+#include <memory>
+#include <string>
+#include <thread>
+#include <vector>
+
+using tcp = boost::asio::ip::tcp;       // from <boost/asio/ip/tcp.hpp>
+namespace http = boost::beast::http;    // from <boost/beast/http.hpp>
+
+// Return a reasonable mime type based on the extension of a file.
+boost::beast::string_view
+mime_type(boost::beast::string_view path)
+{
+    using boost::beast::iequals;
+    auto const ext = [&path]
+    {
+        auto const pos = path.rfind(".");
+        if(pos == boost::beast::string_view::npos)
+            return boost::beast::string_view{};
+        return path.substr(pos);
+    }();
+    if(iequals(ext, ".htm"))  return "text/html";
+    if(iequals(ext, ".html")) return "text/html";
+    if(iequals(ext, ".php"))  return "text/html";
+    if(iequals(ext, ".css"))  return "text/css";
+    if(iequals(ext, ".txt"))  return "text/plain";
+    if(iequals(ext, ".js"))   return "application/javascript";
+    if(iequals(ext, ".json")) return "application/json";
+    if(iequals(ext, ".xml"))  return "application/xml";
+    if(iequals(ext, ".swf"))  return "application/x-shockwave-flash";
+    if(iequals(ext, ".flv"))  return "video/x-flv";
+    if(iequals(ext, ".png"))  return "image/png";
+    if(iequals(ext, ".jpe"))  return "image/jpeg";
+    if(iequals(ext, ".jpeg")) return "image/jpeg";
+    if(iequals(ext, ".jpg"))  return "image/jpeg";
+    if(iequals(ext, ".gif"))  return "image/gif";
+    if(iequals(ext, ".bmp"))  return "image/bmp";
+    if(iequals(ext, ".ico"))  return "image/vnd.microsoft.icon";
+    if(iequals(ext, ".tiff")) return "image/tiff";
+    if(iequals(ext, ".tif"))  return "image/tiff";
+    if(iequals(ext, ".svg"))  return "image/svg+xml";
+    if(iequals(ext, ".svgz")) return "image/svg+xml";
+    return "application/text";
+}
+
+// Append an HTTP rel-path to a local filesystem path.
+// The returned path is normalized for the platform.
+std::string
+path_cat(
+    boost::beast::string_view base,
+    boost::beast::string_view path)
+{
+    if(base.empty())
+        return path.to_string();
+    std::string result = base.to_string();
+#if BOOST_MSVC
+    char constexpr path_separator = '\\';
+    if(result.back() == path_separator)
+        result.resize(result.size() - 1);
+    result.append(path.data(), path.size());
+    for(auto& c : result)
+        if(c == '/')
+            c = path_separator;
+#else
+    char constexpr path_separator = '/';
+    if(result.back() == path_separator)
+        result.resize(result.size() - 1);
+    result.append(path.data(), path.size());
+#endif
+    return result;
+}
+
+// This function produces an HTTP response for the given
+// request. The type of the response object depends on the
+// contents of the request, so the interface requires the
+// caller to pass a generic lambda for receiving the response.
+template<
+    class Body, class Allocator,
+    class Send>
+void
+handle_request(
+    boost::beast::string_view doc_root,
+    http::request<Body, http::basic_fields<Allocator>>&& req,
+    Send&& send)
+{
+    // Returns a bad request response
+    auto const bad_request =
+    [&req](boost::beast::string_view why)
+    {
+        http::response<http::string_body> res{http::status::bad_request, req.version};
+        res.set(http::field::server, BOOST_BEAST_VERSION_STRING);
+        res.set(http::field::content_type, "text/html");
+        res.keep_alive(req.keep_alive());
+        res.body = why.to_string();
+        res.prepare_payload();
+        return res;
+    };
+
+    // Returns a not found response
+    auto const not_found =
+    [&req](boost::beast::string_view target)
+    {
+        http::response<http::string_body> res{http::status::not_found, req.version};
+        res.set(http::field::server, BOOST_BEAST_VERSION_STRING);
+        res.set(http::field::content_type, "text/html");
+        res.keep_alive(req.keep_alive());
+        res.body = "The resource '" + target.to_string() + "' was not found.";
+        res.prepare_payload();
+        return res;
+    };
+
+    // Returns a server error response
+    auto const server_error =
+    [&req](boost::beast::string_view what)
+    {
+        http::response<http::string_body> res{http::status::internal_server_error, req.version};
+        res.set(http::field::server, BOOST_BEAST_VERSION_STRING);
+        res.set(http::field::content_type, "text/html");
+        res.keep_alive(req.keep_alive());
+        res.body = "An error occurred: '" + what.to_string() + "'";
+        res.prepare_payload();
+        return res;
+    };
+
+    // Make sure we can handle the method
+    if( req.method() != http::verb::get &&
+        req.method() != http::verb::head)
+        return send(bad_request("Unknown HTTP-method"));
+
+    // Request path must be absolute and not contain "..".
+    if( req.target().empty() ||
+        req.target()[0] != '/' ||
+        req.target().find("..") != boost::beast::string_view::npos)
+        return send(bad_request("Illegal request-target"));
+
+    // Build the path to the requested file
+    std::string path = path_cat(doc_root, req.target());
+    if(req.target().back() == '/')
+        path.append("index.html");
+
+    // Attempt to open the file
+    boost::beast::error_code ec;
+    http::file_body::value_type body;
+    body.open(path.c_str(), boost::beast::file_mode::scan, ec);
+
+    // Handle the case where the file doesn't exist
+    if(ec == boost::system::errc::no_such_file_or_directory)
+        return send(not_found(req.target()));
+
+    // Handle an unknown error
+    if(ec)
+        return send(server_error(ec.message()));
+
+    // Respond to HEAD request
+    if(req.method() == http::verb::head)
+    {
+        http::response<http::empty_body> res{http::status::ok, req.version};
+        res.set(http::field::server, BOOST_BEAST_VERSION_STRING);
+        res.set(http::field::content_type, mime_type(path));
+        res.content_length(body.size());
+        res.keep_alive(req.keep_alive());
+        return send(std::move(res));
+    }
+
+    // Respond to HEAD request
+    http::response<http::file_body> res{
+        std::piecewise_construct,
+        std::make_tuple(std::move(body)),
+        std::make_tuple(http::status::ok, req.version)};
+    res.set(http::field::server, BOOST_BEAST_VERSION_STRING);
+    res.set(http::field::content_type, mime_type(path));
+    res.content_length(body.size());
+    res.keep_alive(req.keep_alive());
+    return send(std::move(res));
+}
+
+//------------------------------------------------------------------------------
+
+// Report a failure
+void
+fail(boost::system::error_code ec, char const* what)
+{
+    std::cerr << what << ": " << ec.message() << "\n";
+}
+
+// Handles an HTTP server connection
+class session : public std::enable_shared_from_this<session>
+{
+    // This is the C++11 equivalent of a generic lambda.
+    // The function object is used to send an HTTP message.
+    struct send_lambda
+    {
+        session& self_;
+
+        explicit
+        send_lambda(session& self)
+            : self_(self)
+        {
+        }
+
+        template<bool isRequest, class Body, class Fields>
+        void
+        operator()(http::message<isRequest, Body, Fields>&& msg) const
+        {
+            // This function takes ownership of the message by moving
+            // it into a temporary buffer, otherwise we would have
+            // to manage the lifetime of the message and serializer.
+            async_write_msg(
+                self_.socket_,
+                std::move(msg),
+                self_.strand_.wrap(std::bind(
+                    &session::on_write,
+                    self_.shared_from_this(),
+                    std::placeholders::_1)));
+        }
+    };
+
+    tcp::socket socket_;
+    boost::asio::io_service::strand strand_;
+    boost::beast::flat_buffer buffer_;
+    std::string const& doc_root_;
+    http::request<http::string_body> req_;
+    send_lambda lambda_;
+
+public:
+    // Take ownership of the socket
+    explicit
+    session(
+        tcp::socket socket,
+        std::string const& doc_root)
+        : socket_(std::move(socket))
+        , strand_(socket_.get_io_service())
+        , doc_root_(doc_root)
+        , lambda_(*this)
+    {
+    }
+
+    // Start the asynchronous operation
+    void
+    run()
+    {
+        do_read();
+    }
+
+    void
+    do_read()
+    {
+        // Read a request
+        http::async_read(socket_, buffer_, req_,
+            strand_.wrap(std::bind(
+                &session::on_read,
+                shared_from_this(),
+                std::placeholders::_1)));
+    }
+
+    void
+    on_read(boost::system::error_code ec)
+    {
+        // This means they closed the connection
+        if(ec == http::error::end_of_stream)
+            return do_close();
+
+        if(ec)
+            return fail(ec, "read");
+
+        // Send the response
+        handle_request(doc_root_, std::move(req_), lambda_);
+    }
+
+    void
+    on_write(boost::system::error_code ec)
+    {
+        if(ec == http::error::end_of_stream)
+        {
+            // This means we should close the connection, usually because
+            // the response indicated the "Connection: close" semantic.
+            return do_close();
+        }
+
+        if(ec)
+            return fail(ec, "write");
+
+        // Read another request
+        do_read();
+    }
+
+    void
+    do_close()
+    {
+        // Send a TCP shutdown
+        boost::system::error_code ec;
+        socket_.shutdown(tcp::socket::shutdown_send, ec);
+
+        // At this point the connection is closed gracefully
+    }
+};
+
+//------------------------------------------------------------------------------
+
+// Accepts incoming connections and launches the sessions
+class listener : public std::enable_shared_from_this<listener>
+{
+    boost::asio::io_service::strand strand_;
+    tcp::acceptor acceptor_;
+    tcp::socket socket_;
+    std::string const& doc_root_;
+
+public:
+    listener(
+        boost::asio::io_service& ios,
+        tcp::endpoint endpoint,
+        std::string const& doc_root)
+        : strand_(ios)
+        , acceptor_(ios)
+        , socket_(ios)
+        , doc_root_(doc_root)
+    {
+        boost::system::error_code ec;
+
+        // Open the acceptor
+        acceptor_.open(endpoint.protocol(), ec);
+        if(ec)
+        {
+            fail(ec, "open");
+            return;
+        }
+
+        // Bind to the server address
+        acceptor_.bind(endpoint, ec);
+        if(ec)
+        {
+            fail(ec, "bind");
+            return;
+        }
+
+        // Start listening for connections
+        acceptor_.listen(
+            boost::asio::socket_base::max_connections, ec);
+        if(ec)
+        {
+            fail(ec, "listen");
+            return;
+        }
+    }
+
+    // Start accepting incoming connections
+    void
+    run()
+    {
+        if(! acceptor_.is_open())
+            return;
+        do_accept();
+    }
+
+    void
+    do_accept()
+    {
+        acceptor_.async_accept(
+            socket_,
+            std::bind(
+                &listener::on_accept,
+                shared_from_this(),
+                std::placeholders::_1));
+    }
+
+    void
+    on_accept(boost::system::error_code ec)
+    {
+        if(ec)
+        {
+            fail(ec, "accept");
+        }
+        else
+        {
+            // Create the session and run it
+            std::make_shared<session>(
+                std::move(socket_),
+                doc_root_)->run();
+        }
+
+        // Accept another connection
+        do_accept();
+    }
+};
+
+//------------------------------------------------------------------------------
+
+int main(int argc, char* argv[])
+{
+    // Check command line arguments.
+    if (argc != 5)
+    {
+        std::cerr <<
+            "Usage: http-server-async <address> <port> <doc_root> <threads>\n" <<
+            "Example:\n" <<
+            "    http-server-async 0.0.0.0 8080 . 1\n";
+        return EXIT_FAILURE;
+    }
+    auto const address = boost::asio::ip::address::from_string(argv[1]);
+    auto const port = static_cast<unsigned short>(std::atoi(argv[2]));
+    std::string const doc_root = argv[3];
+    auto const threads = std::max<std::size_t>(1, std::atoi(argv[3]));
+
+    // The io_service is required for all I/O
+    boost::asio::io_service ios{threads};
+
+    // Create and launch a listening port
+    std::make_shared<listener>(
+        ios,
+        tcp::endpoint{address, port},
+        doc_root)->run();
+
+    // Run the I/O service on the requested number of threads
+    std::vector<std::thread> v;
+    v.reserve(threads - 1);
+    for(auto i = threads - 1; i > 0; --i)
+        v.emplace_back(
+        [&ios]
+        {
+            ios.run();
+        });
+    ios.run();
+
+    return EXIT_SUCCESS;
+}