Update for Net-TS Asio (API Change):

fix #769

The following classes are removed:

* handler_type
* async_result
* async_completion
* is_dynamic_buffer
* is_const_buffer_sequence
* is_mutable_buffer_sequence
* handler_alloc

Actions Required:

* Use BOOST_ASIO_HANDLER_TYPE instead of handler_type
* Use BOOST_ASIO_INITFN_RESULT_TYPE instead of async_result
* Use boost::asio::async_completion
* Use boost::asio::is_dynamic_buffer
* Use boost::asio::is_const_buffer_sequence
* Use boost::asio::is_mutable_buffer_sequence
* boost::asio::associated_allocator_t replaces handler_alloc

test/doc/core_snippets.cpp

@@ -27,12 +27,12 @@ void fxx()
 //
 using namespace boost::beast;
 
-boost::asio::io_service ios;
-boost::asio::io_service::work work{ios};
-std::thread t{[&](){ ios.run(); }};
+boost::asio::io_context ioc;
+auto work = boost::asio::make_work_guard(ioc);
+std::thread t{[&](){ ioc.run(); }};
 
 error_code ec;
-boost::asio::ip::tcp::socket sock{ios};
+boost::asio::ip::tcp::socket sock{ioc};
 
 //]
 
@@ -40,9 +40,10 @@ boost::asio::ip::tcp::socket sock{ios};
 //[snippet_core_2
 
 char const* const host = "www.example.com";
-boost::asio::ip::tcp::resolver r{ios};
-boost::asio::ip::tcp::socket stream{ios};
-boost::asio::connect(stream, r.resolve({host, "http"}));
+boost::asio::ip::tcp::resolver r{ioc};
+boost::asio::ip::tcp::socket stream{ioc};
+auto const results = r.resolve(host, "http");
+boost::asio::connect(stream, results.begin(), results.end());
 
 // At this point `stream` is a connected to a remote
 // host and may be used to perform stream operations.
@@ -59,7 +60,7 @@ void write_string(SyncWriteStream& stream, string_view s)
 {
     static_assert(is_sync_write_stream<SyncWriteStream>::value,
         "SyncWriteStream requirements not met");
-    boost::asio::write(stream, boost::asio::const_buffers_1(s.data(), s.size()));
+    boost::asio::write(stream, boost::asio::const_buffer(s.data(), s.size()));
 }
 
 //]