[/
 / Copyright (c) 2003-2025 Christopher M. Kohlhoff (chris at kohlhoff 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)
 /]

[section:channels Channels]

[note This is an experimental feature.]

The templates
[link asio.reference.experimental__basic_channel experimental::basic_channel]
and [link asio.reference.experimental__basic_concurrent_channel
experimental::basic_concurrent_channel], with aliases `experimental::channel`
and `experimental::concurrent_channel`, may be used to send messages between
different parts of the same application. A ['message] is defined as a
collection of arguments to be passed to a completion handler, and the set of
messages supported by a channel is specified by its template parameters.
Messages may be sent and received using asynchronous or non-blocking
synchronous operations.

For example:

  // Create a channel with no buffer space.
  channel<void(error_code, size_t)> ch(ctx);

  // The call to try_send fails as there is no buffer
  // space and no waiting receive operations.
  bool ok = ch.try_send(asio::error::eof, 123);
  assert(!ok);

  // The async_send operation is outstanding until
  // a receive operation consumes the message.
  ch.async_send(asio::error::eof, 123,
      [](error_code ec)
      {
        // ...
      });

  // The async_receive consumes the message. Both the
  // async_send and async_receive operations complete
  // immediately.
  ch.async_receive(
      [](error_code ec, size_t n)
      {
        // ...
      });

[heading See Also]

[link asio.reference.experimental__basic_channel experimental::basic_channel],
[link asio.reference.experimental__basic_concurrent_channel experimental::basic_concurrent_channel],
[link asio.examples.cpp20_examples.channels Channels examples (C++20)].

[endsect]
