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| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="boost_asio.overview.rationale"></a><a class="link" href="rationale.html" title="Rationale">Rationale</a> |
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| <p> |
| Most programs interact with the outside world in some way, whether it be |
| via a file, a network, a serial cable, or the console. Sometimes, as is the |
| case with networking, individual I/O operations can take a long time to complete. |
| This poses particular challenges to application development. |
| </p> |
| <p> |
| Boost.Asio provides the tools to manage these long running operations, without |
| requiring programs to use concurrency models based on threads and explicit |
| locking. |
| </p> |
| <p> |
| 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 addresses the following goals: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"> |
| <span class="bold"><strong>Portability.</strong></span> The library should support |
| a range of commonly used operating systems, and provide consistent behaviour |
| across these operating systems. |
| </li> |
| <li class="listitem"> |
| <span class="bold"><strong>Scalability.</strong></span> The library should facilitate |
| the development of network applications that scale to thousands of concurrent |
| connections. The library implementation for each operating system should |
| use the mechanism that best enables this scalability. |
| </li> |
| <li class="listitem"> |
| <span class="bold"><strong>Efficiency.</strong></span> The library should support |
| techniques such as scatter-gather I/O, and allow programs to minimise |
| data copying. |
| </li> |
| <li class="listitem"> |
| <span class="bold"><strong>Model concepts from established APIs, such as BSD |
| sockets.</strong></span> The BSD socket API is widely implemented and understood, |
| and is covered in much literature. Other programming languages often |
| use a similar interface for networking APIs. As far as is reasonable, |
| Boost.Asio should leverage existing practice. |
| </li> |
| <li class="listitem"> |
| <span class="bold"><strong>Ease of use.</strong></span> The library should provide |
| a lower entry barrier for new users by taking a toolkit, rather than |
| framework, approach. That is, it should 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. |
| </li> |
| <li class="listitem"> |
| <span class="bold"><strong>Basis for further abstraction.</strong></span> 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. |
| </li> |
| </ul></div> |
| <p> |
| Although Boost.Asio started life focused primarily on networking, its concepts |
| of asynchronous I/O have been extended to include other operating system |
| resources such as serial ports, file descriptors, and so on. |
| </p> |
| </div> |
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| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2003 - 2010 Christopher M. Kohlhoff<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) |
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