asio C++ library


C++03 Examples


This example shows how to customise the allocation of memory associated with asynchronous operations.


This example demonstrates how to create reference counted buffers that can be used with socket read and write operations.


This example implements a chat server and client. The programs use a custom protocol with a fixed length message header and variable length message body.

The following POSIX-specific chat client demonstrates how to use the posix::stream_descriptor class to perform console input and output.


A collection of simple clients and servers, showing the use of both synchronous and asynchronous operations.


These POSIX-specific examples show how to use Asio in conjunction with the fork() system call. The first example illustrates the steps required to start a daemon process:

The second example demonstrates how it is possible to fork a process from within a completion handler.

HTTP Client

Example programs implementing simple HTTP 1.0 clients. These examples show how to use the read_until and async_read_until functions.

HTTP Server

This example illustrates the use of asio in a simple single-threaded server implementation of HTTP 1.0. It demonstrates how to perform a clean shutdown by cancelling all outstanding asynchronous operations.

HTTP Server 2

An HTTP server using an io_context-per-CPU design.

HTTP Server 3

An HTTP server using a single io_context and a thread pool calling io_context::run().

HTTP Server 4

A single-threaded HTTP server implemented using stackless coroutines.


This example shows how to use raw sockets with ICMP to ping a remote host.


This example shows how to customise handler invocation. Completion handlers are added to a priority queue rather than executed immediately.


Two examples showing how to use ip::tcp::iostream.


An example showing the use of multicast to transmit packets to a group of subscribers.


This example shows how Boost.Serialization can be used with asio to encode and decode structures for transmission over a socket.


This example demonstrates how to integrate custom functionality (in this case, for logging) into asio's io_context, and how to use a custom service with basic_stream_socket<>.


Example client program implementing the SOCKS 4 protocol for communication via a proxy.


Example client and server programs showing the use of the ssl::stream<> template with asynchronous operations.


A collection of examples showing how to cancel long running asynchronous operations after a period of time.


Example showing how to customise basic_waitable_timer using a different clock type.


Example illustrating mixed synchronous and asynchronous operations, and how to use Boost.Lambda with Asio.


Example demonstrating reactor-style operations for integrating a third-party library that wants to perform the I/O operations itself.


Example of using the asio::spawn() function, a wrapper around the Boost.Coroutine library, to implement a chain of asynchronous operations using stackful coroutines.

UNIX Domain Sockets

Examples showing how to use UNIX domain (local) sockets.


An example showing how to use the Windows-specific function TransmitFile with Asio.