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# Boost.Asio

Boost.Asio is a cross-platform C++ library for network programming that provides developers with a consistent asynchronous I/O model using a modern C++ approach.

## Getting Started

The tutorial introduces the fundamental concepts required to use Boost.Asio, and shows how to use Boost.Asio to develop simple client and server programs.

The examples illustrate the use of Boost.Asio in more complex applications.

## Dependencies

There is no need to build any of the Boost libraries to use most of Boost.Asio, and only the header files are required. However, some overloads of `read_until` and `async_read_until` require the Boost.Regex library. (Note: with MSVC or Borland C++ you may need to add -DBOOST_ALL_NO_LIB to your project settings to disable autolinking of the Boost.Date_Time and Boost.Regex libraries.)

To use the SSL support, OpenSSL is required. OpenSSL is not necessary to use the rest of Boost.Asio.

## Supported Platforms

The following platforms and compilers have been tested:

- Win32 using Visual C++ 7.1 and Visual C++ 8.0.
- Win32 using Borland C++Builder 6 patch 4.
- Win32 using MinGW.
- Win32 using Cygwin. (__USE_W32_SOCKETS must be defined.)
- Linux (2.4 or 2.6 kernels) using g++ 3.3 or later.
- Solaris using g++ 3.3 or later.
- Mac OS X 10.4 using g++ 3.3 or later.
- QNX Neutrino 6.3 using g++ 3.3 or later.

## Rationale

The Boost.Asio library is intended for programmers using C++ for systems programming, where access to operating system functionality such as networking is often required. In particular, Boost.Asio attempts to address the following goals:

- Portability. The library should support, and provide consistent behaviour across, a range of commonly used operating systems.
- Scalability. The library should allow, and indeed encourage, the development of network applications that scale to hundreds or thousands of concurrent connections. The library implementation for each operating system should use the mechanism that best enables this scalability.
- Efficiency. The library should support techniques such as scatter-gather I/O, and allow protocol implementations that minimise data copying.
- Model Berkeley sockets. The Berkeley sockets API is widely implemented and understood, as well as being covered in much literature. Other programming languages often use a similar interface for networking APIs.
- Ease of use. Lower the entry barrier for new users by taking a toolkit, rather than framework, approach. That is, try to minimise the up-front investment in time to just learning a few basic rules and guidelines. After that, a library user should only need to understand the specific functions that are being used.
- Basis for further abstraction. The library should permit the development of other libraries that provide higher levels of abstraction. For example, implementations of commonly used protocols such as HTTP.

Although the current incarnation of Boost.Asio focuses primarily on networking, its concepts of asynchronous I/O can be extended to include other operating system resources such as files.

| Copyright © 2003 - 2006 Christopher M. Kohlhoff