Release Notes

Boost 1.84

API Changes

Remove deprecated allocation and invocation hooks

Features

Support for immediate_executor

Fixes

#2766 Use the explicit type std::size_t when completing transfer_op
#2727 Replaced BOOST_ASIO_INITFN_RESULT_TYPE with BOOST_ASIO_INITFN_AUTO_RES
#2715 server-flex-awaitable example resets parser

Documentation

#2713 Corrected the websocket::stream::async_ping/pong handler requirement
#2755 Update documentation for websocket::stream::async_write_some

Boost 1.83

Fixes

#2680 aligned_storage unused for C+23
#2653 MSVC literal not error
#2661 ssl_stream ambiguity error on clang
#2649 Jamefile uses openssl.jam

Boost 1.82

Features

#2475 Add error_codes use source_location

Fixes

#2602 tcp_stream uses the correct executor of the timer.
#2638 std::placeholders ambiguity fix.

Improvements

error_categories use numeric ids
file_body support seek

Boost 1.81

Features

Add buffers_generator
Add http::message_generator
Add buffer_ref
Support for per-operation cancellation

Fixes

#2439 Fix CVE-2018-25032 in zlib streams
#264 Websocket support continue in upgrade
#471 Unquote takes s by reference

Improvements

#2104 C++20 awaitable examples.
#226, #227 per-message compression options
#2449 websocket timeout option api
#2468 multiple content length error

Miscellaneous

Use span from Boost.Core
Use static_string from Boost.StaticString
serializer::is_done is const
Support for default-completion and rebind
#2469 s390x architecture support

Documentation

#891 Feature table for buffers
#516 Case-insensitivity for fields is stated
#298 api version is documented

Boost 1.80

Miscellaneous

#2363 Remove BOOST_BEAST_USE_STD_STRING_VIEW
#2417 use boost::core::string_view. This improves inter-conversion between string_view implementations. Some observable differences for users:
- core::string_view no longer supports the .to_string() or .clear() extensions from Utility
- code that relied on .max_size() returning .size(), needs to be fixed to use .size() instead
- remove_suffix() and remove_prefix() were more lenient than the standard specs; be sure you don't rely on it clamping the argument to valid range
- BOOST_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS no longer suppresses conversions to std::string

Boost 1.79

Fixes

#2391 Add missing include for file_body test.
#2364 Fix WebSocket handshake response on failure.
#2280 (related) Fix open append mode for file_posix.
#2280 Fix open append mode for file_win32.
#2280 Fix file open with append/append_existing flag on Windows
#2354 Fix clang-cl UTF8 path handling for file_win32.
#2354 Fix clang-cl UTF8 path handling for file_stdio.

Miscellaneous

#2375 Add ARM64 builds to drone CI
#2217 Fix async_base documentation link
#2280 Add tests for file open in append/append_existing mode
#2351 Update CI to include gcc 11, clang 12, msvc 14.3
#2350 Add individual tests to CMake workflow

Boost 1.78

Fixes

Fix CVE-2016-9840 in zlib implementation.
Fix TLS SNI handling in websocket_client_async_ssl example.
#2313 Fix reuse of sliding window in WebSocket permessage_deflate.
Fix accept error handling in http_server_async example.

Miscellaneous

Remove test framework's dependency on RTTI.
Move library-specific docca configuration to Beast.
Remove dependency on RTTI in test::stream.
Fix missing includes in test headers.

Boost 1.77

Fixes

#2233 Remove use of POSIX-only constant.

Miscellaneous

Fixes to tests.
Improvements and fixes in Github and Drone CI.
Accommodate Docca updates.
Update example root certificates.
Add example of reading large response body.
Remove Travis CI.
Update CMakeLists.txt

Boost 1.76

Fixes

#2139 Add executor rebind to test::stream.
Fix unused variable compiler warning in WebSocket async shutdown.

Improvements

#2124 Floating point support no longer required to use Beast.
Reduce size of websockety compiled code by using a common buffers type for all operations.
HTTP Parser has improved detection of incorrect use.

Miscellaneous

#2140 Add cxxstd tag to library metadata.
Move to Drone CI.
Minor documentation formatting improvements.
CML now finds required Boost::thread library during in-tree build.

Boost 1.75

Fixes

Eliminate spurious unused parameter warning in detect_ssl.
Update Websocket examples to set the SNI for TLS connections.
#2023 websocket async_shutdown will now shutdown the underlying TLS transport.
#2011 File open with append_existing flag now works correctly in posix environments.
#2039 Windows builds now link to bcrypt as required by the filesystem library.
#2063 Logic error fixed in advanced_server_flex example.
#1582 Fix unreachable code error on MSVC.
#2070 Fix http body behaviour when body_limit it none.
#2065 Fix behaviour of basic_stream when a zero-length write is requested.
#2080 Add enums representing Sec-* HTTP headers.
#2085 Fix nullptr implicit cast on fields::set().
#2029 Fix C++20 tests for basic_stream.

Miscellaneous

Add handler tracking to asynchronous operations:
- Define the preprocessor macro BOOST_ASIO_ENABLE_HANDLER_TRACKING to enable Asio handler tracking in Boost.Beast asynchronous operations. Please see asio handler tracking for details.
Add Bishop-Fox 2020 Security Assessment.

Boost 1.74

API Changes

The API to Asio has undergone changes. Please refer to the Asio release notes for details.
Beast has been updated to track and respect developer choices in the use of Asio. In particular:
- Define BOOST_ASIO_NO_DEPRECATED to disallow deprecated invocation hooks.
- Define BOOST_ASIO_NO_TS_EXECUTORS to ensure that executors conform to the Standard Executors proposal.
- Define BOOST_ASIO_USE_TS_EXECUTOR_AS_DEFAULT to select Networking TS style executors by default. If this macro is not defined, Asio default executors will be the Standard Executors implementation.
#1897 Parser body_limit is optional (API Change) Actions Required
- The signature of basic_parser<>::body_limit(n) has changed. It now accepts an optional std::uint64_t. The caller may indicate that no body limit is required by calling body_limit(boost::none). The default limits remain in place in order to maintain 'safe by default' behaviour.
#1934 Remove deprecated interfaces (API Change) Actions Required
- The macro BOOST_BEAST_NO_DEPRECATED will no longer be noticed by Beast. The only way to enable deprecated functionality is now the macro BOOST_BEAST_ALLOW_DEPRECATED which is undefined by default. That is, all deprecated behaviour is disabled by default.
- The following deprecated functions have been removed:
  - websocket::async_accept_ex
  - websocket::async_handshake_ex
  - websocket::accept_ex
  - websocket::handshake_ex Programs still using these names should be refactored to use the decorator feature and the remaining handshake and accept functions.
- websocket::role_type has been removed. Users should use beast::role_type instead.
- handler_ptr has been removed. Users should use net::bind_handler and/or bind_front_handler instead.
- Code that depends on mutable_data_type should be refactored to use mutable_buffers_type. Classes affected are:
  - buffers_adaptor
  - flat_buffer
  - flat_static_buffer
  - multi_buffer
  - static_buffer
- The reset function has been removed from flat_static_buffer. Use the clear function instead.
- The core/type_traits.hpp public header has been removed and along with it the type trait is_completion_handler. Beast uses the CompletionHandler correctness checks provided by Asio. In a c++20 environment, these convert to concept checks.
- The error code enum invalid_code_lenths (sic) was a synonym of invalid_code_lengths. Affected programs should be modified to use invalid_code_lengths.
- The file core/buffers_adapter.hpp has been removed along with the deprecated alias typename buffers_adapter. Affected programs should use core/buffers_adapator.hpp and the type buffers_adaptor.
#1956 Deprecate string_param (API Change) Actions Required string_param, which was previously the argument type when setting field values has been replaced by string_view. Because of this, it is no longer possible to set message field values directly as integrals. Users are requied to convert numeric arguments to a string type prior to calling fields::set et. al. Beast provides the non-allocating to_static_string() function for this purpose. To set Content-Length field manually, call message::content_length.

Fixes

#1913 Fix standalone compilation error with std::string_view
#1925 #1916 Fix compile errors on Visual Studio with /std:c++latest
#1924 Fix c++20 deprecation warning in span_body
#1920 Fix use buffered_read_stream with use_awaitable
#1918 Fix async_detect_ssl with use_awaitable
#1944 Fix FILE namespace qualification
#1942 Fix http read bytes_transferred
#1943 Fix basic_stream expires_after
#1980 Fix max compile error
#1949 iless and iequal take part in Heterogeneous Lookup

Miscellaneous

#1907 OpenSSL 1.0.2 or later is required when using SSL/TLS streams. This is a requirement inherited from Boost.Asio.
Additional tests have been added to ensure correct integration with C++20 coroutines when avaialable.

Boost 1.73

API Changes

Nested mutable_data_type in Beast dynamic buffers is deprecated. Affected types:
- buffers_adaptor
- flat_buffer
- flat_static_buffer
- multi_buffer
- static_buffer

Changes Required

Use nested mutable_buffers_type instead of mutable_data_type, or define BOOST_BEAST_ALLOW_DEPRECATED

Miscellaneous

Update root certificates in examples

Fixes

#1880 Fix Content-Length parsing
#1852 Fix examples to dispatch to strand
#1875 Ensure basic_stream::close will not throw
#1863 Field digest is endian-independent
#1853 Fix ostream flush
#1831 flat_buffer::shrink_to_fit is noexcept
#1828 Fix erase field
#1822 Examples use strands correctly
#1818 file_body returns short_read on eof during read
#1786 Fix bug in win32 file_body
#1260 Add accessor function to File member of basic_file_body
#793 file_win32 supports UTF-8 paths
#793 file_stdio supports unicode paths
#1786 file_win32 bodies respect http::serializer::split
Correct buffer_bytes documentation
Fix missing include in sha1.hpp
Fix ostream warning
Update broken links in README
Translate some win32 errors to net error codes
Moved-from dynamic buffers do not clear if different allocator
Fix compilation macro documentation
Clarify end-of-file behaviour in File::read docs
ostream_buffer satisfies preconditions of DynamicBuffer_v1::commit
Fix release build of docs
Fix echo-op test
Fix non-msvc cmake

Boost 1.72

Examples

Add async-ssl-system-executor http client example
Add async-ssl-system-executor websocket client example

Features

Async init-fns use the executor's default token
Use automatically deduced return types for all async operations (since C++14)
Support Concepts for completion token params

Fixes

#1664 Add default dtors to satisfy -Wnon-virtual-dtor
#1682 Multiple I/O of the same type is not supported
#1687 Fix signed/unsigned mismatch in file_stdio::seek
#1688 basic_stream dtor cannot throw
#1734 Fix leftovers in basic_parser corner case:
#1751 https_get example sends the Host header
#1754 Fix async_close error code when async_read times out
#1782 root_certificates.hpp is not for production
Fix data race in websocket examples
Fix data race in http server examples
Squelch spurious websocket timer assert
Use the executor type in basic_stream timer

Boost 1.71

Improvements

#1280 Add 1-element specialization for buffers_cat
#1556 Set parser status and flags even if body limit has been reached
#1567 Relax requirements for vector_body
#1568 detect_ssl uses bool instead of tribool
#1574 Replace static_string in HTTP parser
#1606 Use steady_timer type
#1611 Make chat websocket javascript client more user friendly
#1613 Remove redundant use of static_string
#1636 Improve performance of http::string_to_verb
Preserve operation_aborted on partial message
Remove unused <experimental/unit_test/thread.hpp>
Reduce the number of instantiations of filter_token_list
Add idle ping suspend test
Remove the use of bind_executor in basic_stream
Remove redundant template in service_base
Remove the use of static_string from http::fields
Enable split compilation in http::basic_fields
Remove redundant instation of static_string in websocket
Remove redundant use of asio::coroutine in flat_stream
More split compilation in rfc7230.hpp
More split compilation in websocket/detail/mask.hpp
Simplify generation of sec-websocket-key

Fixes

#1332 allocator_traits::construct is used for user-defined types
#1559 Member get_executor const-correctness
#1569 Fix async_detect_ssl handler type
#1570 Launder pointers
#1578 Fix min/max on MSVC
#1586 Fix uninitalized memory use in deflate_stream
#1593 Fix UB in websocket close tests
#1594 Fix data race in test stream
#1599 Fix moved-from executor in idle ping timeout
#1607 Remove uses of the deprecated buffers function
#1612 Remove uses of deprecated methods in websocket tests
#1620 Clean up typo in chat websocket javascript client
#1621 Fix flat_buffer copy members
Silence gcc-8 warning
Fix buffers_cat iterator tests
Don't pessimize-move
Qualify calls to beast::iequals in basic_parser.ipp
Fix UB in websocket read tests
Simplify websocket::detail::prng
Don't over-allocate in http::basic_fields

Documentation

Documentation is built with SaxonHE instead of xsltproc

Boost 1.70

	Tip
	The namespace alias `net` is used throughout for `boost::asio`.

New Features

All composed operations use the new net::async_initiate internally.
New tcp_stream and basic_stream support:
- Timeouts, async_read_some, async_write_some complete with error::timeout on expiration.
- Traffic-shaping policies simple and unlimited, or a user-defined RatePolicy.
- Supports P1322R0.
websocket::stream supports
- Configurable handshake timeout
- Configurable idle timeout
- Automatic idle pings
ssl_stream is a public interface
( #1305) Better flat_buffer, flat_static_buffer, multi_buffer, and static_buffer:
- Revise all reference documentation
- Move construction does not always invalidate buffers
- non-const data() returns a mutable buffer sequence
- Add cdata() to also return constant readable bytes
- Eligible member functions are declared noexcept
( #1345) Better flat_buffer, multi_buffer
- Add clear, reserve(), max_size(), shrink_to_fit()
- Respect Allocator max_size()
- Specify exception safety
( #1384) New functions bind_front_handler
Better static_buffer, flat_static_buffer
- Add clear()
- More members are noexcept
- Specify exception safety
Faster http::string_to_field
Dynamic buffer clear operations perserve capacity.
New file <boost/beast/core/buffer_traits.hpp>
- New variadic is_const_buffer_sequence
- New variadic is_mutable_buffer_sequence
- New trait buffers_iterator_type
- New trait buffers_type
New classes async_base, stable_async_base
- Handle boilerplate for writing composed operations
- New allocate_stable is preferred over handler_ptr
New buffer_bytes replacement for net::buffer_size
New:
- saved_handler
- buffers_range_ref
- executor_type
- get_lowest_layer, lowest_layer_type
- close_socket, beast_close_socket
- error, condition
These interfaces are now public (were experimental): flat_stream, detect_ssl, async_detect_ssl.
Websocket streams use PCG as the fast random number generator, for increased security.

Documentation

WebSocket reference documentation is revised
Updated Networking Refresher
Revised Asynchronous Echo
Rewritten Detect SSL Handshake

API Changes

The Fields concept is deprecated and will be removed in a future version. Actions Required: Do not rely on the Fields concept.
handler_ptr is deprecated. Actions Required: Use stable_async_base and allocate_stable instead.
On Windows, Visual Studio 2017 or later is required
OpenSSL is required to build the examples and tests
HTTP stream algorithms return the number of bytes transferred from the stream. Previously, they returned the number of bytes consumed by the parser. Actions Required:
- Callers depending on the return value of http::read or http::async_read overloads should adjust the usage of the returned value as needed.
Metafunctions has_get_executor, is_sync_stream, is_sync_read_stream, is_sync_write_stream, is_async_stream, is_async_read_stream, and is_async_write_stream are in stream_traits.hpp. Actions Required: Include stream_traits.hpp as needed.
basic_parser is abstract. Actions Required
- Change uses of the basic_parser type to omit the Derived template parameter
- Classes derived from basic_parser no longer need to friend the base.
- Virtual functions in the derived class may be marked override.
Metafunction is_file is in file_base.hpp. Actions Required: Include file_base.hpp as needed.
flat_static_buffer::reset() is deprecated. Actions Required:
- call clear() instead.
buffers_adapter is spelled buffers_adaptor. Actions Required:
- Replace buffers_adapter with buffers_adaptor, or define BOOST_BEAST_ALLOW_DEPRECATED.
buffers is spelled make_printable. Actions Required:
- Replace buffers with make_printable, and include "make_printable.hpp" instead of "ostream.hpp".
file_mode::append_new is removed, as it makes no sense. Actions Required:
- Replace file_mode::append_new with either file_mode::append or file_mode::append_existing as needed.
role_type is moved from websocket to beast
buffers_range_ref is preferred to std::reference_wrapper. Actions Required:
- Call buffers_range_ref with the buffer, instead of calling buffers_range with a reference wrapper constructed from the buffer.
Nested lowest_layer and lowest_layer_type are removed. Actions Required: Use the free function get_lowest_layer and the type trait lowest_layer_type instead.
WebSocket decorator is a socket option:
- Overloads of the following functions which accept a Decorator are deprecated:
  - accept, accept_ex
  - handshake, handshake_ex
  - async_accept, async_accept_ex
  - async_handshake, async_handshake_ex
( #1375) The value returned from basic_parser::content_length no longer changes as the body of the message is received. Actions Required: Call basic_parser::content_length_remaining instead of basic_parser::content_length in order to determine the remaining number of bytes in the body.

Examples

All example programs are updated:
- Use tcp_stream with timeouts (HTTP)
- Use ssl_stream
- Set timeouts for WebSocket streams.
- Use bind_front_handler
( #1100) http-crawl clears the response before each read
( #1347) echo-op is rewritten
( #1401) Examples use flat_buffer
Advanced servers use HTTP parser interfaces for reading
detect-ssl is rewritten
New example example/websocket/server/chat-multi
async_echo works with move-only handlers
cppcon2018 example is removed

Fixes

( #38) Better treatment of SSL short reads
( #1223) HTTP read counts bytes correctly when an error occurs
( #1247) Update ssl_stream for Asio changes
( #1279) Enable explicit instantiations of websocket::stream
( #1290) Don't use deprecated Asio interfaces
( #1306) http::message is not-a boost::empty_value
( #1306) test::stream has fewer dependencies
( #1358) Destroy abandoned websocket ops on shutdown
( #1365) Handler wrappers decay parameters sooner
( #1408) session_alloc is thread-safe
( #1414) Boost.System is header-only
( #1418) test::stream maintains a handler work guard
( #1445) Fix posix_file::close handling of EINTR
( #1460) Large WebSocket Upgrade response no longer overflows
Reusing an HTTP parser returns an error
Handler bind wrappers use the associated allocator
buffers_cat correctly skips empty buffers when iterated
ostream does not overflow or exceed the dynamic buffer's maximum size
Fixes to test::stream::async_read
file_mode::append_existing works correctly
A handler work guard is maintained on paused websocket operations
All behavior of default-constructed iterators is conforming

Boost 1.69

New Videos

New Features

( #1133) Add BOOST_BEAST_USE_STD_STRING_VIEW

Examples

New WebSocket server and browser-based client: example/cppcon2018

Fixes

( #1245) Fix a rare case of incorrect UTF8 validation
( #1237) Verify certificates in client examples
( #1233) Use boost::empty_value
( #1091) Fix timer on websocket upgrade in examples
( #1270) basic_fields uses intrusive base hooks
( #1267) Fix parsing of out-of-bounds hex values
( #1263) Fix uninitialized comparison in buffers iterator
( #1288) Remove extraneous strand from example
Workaround for http-server-fast and libstdc++
Partial support for BOOST_NO_EXCEPTIONS

Experimental

Add timeout_socket

This version fixes a missing executor work guard in all composed operations used in the implementation. Users who are experiencing crashes related to asynchronous completion handlers are encouraged to upgrade. Also included is an improved mechanism for generating random numbers used to mask outgoing websocket frames when operating in the client mode. This resolves a vulnerability described in the Beast Hybrid Assessment Report from Bishop Fox.

New Features

The include directory <beast/experimental> contains features which are not part of the stable public interface but are available anyway. They may change in future versions.

( #1108) New flat_stream for working around an SSL stream performance limitation
( #1151, #595) New http::icy_stream stream filter allows parsing ICY HTTP response handshakes
New ssl_stream for better SSL performance and move constructability
New test::connect, test::error, test::fail_count, and test::stream utilities for writing unit tests.
New http::is_mutable_body_writer metafunction
New websocket::seed_prng for manually providing entropy to the PRNG
New websocket::stream::secure_prng to control whether the connection uses a secure PRNG

Improvements

Generated WebSocket masks use a secure PRNG by default
Improvements to buffers_adaptor
( #1188) Set "/permissive-" for MSVC builds
( #1109) Use a shared string for example HTTP server doc roots
( #1079) Add handler_ptr::has_value

Fixes

( #1073) Fix race in advanced server examples
( #1076) Use executor_work_guard in composed operations
( #1079) Remove spurious assert
( #1113) Add const and non-const overloads for message based HTTP writes
( #1119) Fix unused variable warning
( #1121) Examples use the root certificate which matches the fingerprint
( #1141) Tidy up composed operation doc
( #1186) Check error in example set_option
( #1210) Fix http_server_stackless_ssl.cpp example
( #1211) Fix parse_dec algorithm
( #1214) Silence ubsan false positive
Tidy up websocket stream javadocs
Fix move-only arguments in bind_handler
Fix http::parser constructor javadoc
Fix buffers_adaptor iterator value type
Fix buffers_adaptor::max_size
Fix buffers_prefix iterator decrement
Fix Fields, FieldsWriter concept docs
Fix BodyReader constructor requirements doc

Breaking Changes

Remove deprecated serializer::reader_impl
Remove deprecated Body reader and writer ctor signatures

Boost 1.67

This version fixes significant defects in websocket::stream which can lead to asserts or undefined behavior. Users are encouraged to update to the latest Boost release.

New Features

Move-only completion handlers are supported throughout the library
( #899) Advanced server examples support idle websocket pings and timeouts
( #849) WebSocket permessage-deflate support is now a compile-time feature. This adds an additional bool template parameter to websocket::stream When deflateSupported is true, the stream will be capable of negotiating the permessage-deflate websocket extension per the configured run-time settings. When deflateSupported is false, the stream will never negotiate the permessage-deflate websocket extension. Furthermore, all of the code necessary for implementing the permessage-deflate extension will be excluded from function instantiations. Programs which set deflateSupported to false when instantiating streams will be smaller.
( #949) WebSocket error codes are revised. New error codes are added for more fine-grained failure outcomes. Messages for error codes are more verbose to help pinpoint the problem. Error codes are now also mapped to newly added error conditions to simplify comparisons. The error codes websocket::error::failed and websocket::error::handshake_failed are removed. Actions required: Code which explicitly compares error_code values against the constant websocket::error::handshake_failed should compare against websocket::condition::handshake_failed instead. Code which explicitly compares error_code values against the constant websocket::error::failed should compare against websocket::condition::protocol_violation instead.

Improvements

( #857) http::basic_fields uses less storage
( #894) http::basic_fields exception specifiers are provided
Implementation no longer uses deprecated asio::null_buffers
Add <boost/beast/websocket/stream_fwd.hpp>
( #955) The asynchronous SSL detector example uses a stackless coroutine
bind_handler works with boost placeholders
Examples set reuse_address(true)
( #1026) Advanced servers support clean shutdown via SIGINT or SIGTERM
Some basic_fields operations now give the strong exception guarantee

Fixes

Fix "warning: ‘const’ type qualifier on return type has no effect"
( #916) Tidy up ssl_stream special members
( #918) Calls to <algorithm> are protected from macros
( #954) The control callback is invoked on the proper executor
( #994) Fix iterator version of http::basic_fields::erase
( #992) Fix use-after-move in example request handlers
( #988) Type check completion handlers
( #985) Tidy up bind_handler doc
Fix memory leak in advanced server examples
( #1000) Fix soft-mutex assert in websocket stream. This resolves the assert "ws_.wr_block_ == tok_".
( #1019) Fix fallthrough warnings
( #1024) Fix teardown for TIME_WAIT
( #1030) Fix big-endian websocket masking
Safe treatment of zero-length string arguments in basic_fields
( #1043) Examples clear the HTTP message before reading
( #1012) Add asio_handler_invoke overloads for stream algorithms
Add Access-Control-Expose-Headers field constant

API Changes

Remove unintended public members of handler_ptr. Actions required: don't call non-public members.
handler_ptr is a move-only type, with unique_ptr semantics. Actions required: user-defined composed operations using handler_ptr to manage state can only be moved, not copied.
handler_ptr gives the strong exception guarantee. The constructor signature for managed objects constructed by handler_ptr now receives a const reference to the handler. Actions required: Change the constructor signature for state objects used with handler_ptr to receive a const reference to the handler.
( #896) http::basic_fields does not support fancy pointers
http::parser is no longer MoveConstructible
( #930) http::serializer::reader_impl is deprecated and will be removed in the next release. Actions required: Call http::serializer::writer_impl instead of serializer::reader_impl.
( #884) The BodyReader and BodyWriter concept constructor requirements have changed. They now require the header and body elements to be passed as distinct http::header and value_type objects. This enables the composition of body types. The previous single-argument constructors are deprecated and will be removed in the next version. Actions required: Change user-defined instances of BodyReader or BodyWriter constructor signatures to the two-argument form. Alternatively. define the macro BOOST_BEAST_ALLOW_DEPRECATED in the project (which will cause both the new and the deprecated signatures to be accepted).
websocket::stream::control_callback now copies or moves the function object.
( #1014) DynamicBuffer input areas are not mutable. Actions required: do not attempt to write to input areas of dynamic buffers.
( #941) get_lowest_layer is now a type alias. Actions required: Replace instances of typename get_lowest_layer<T>::type with get_lowest_layer<T>.

Boost 1.66

Initial release