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          <div class="yui-g" id="reference-http_server">
  <div class="section" id="cpp-netlib-http-server-api">
<h1>HTTP Server API<a class="headerlink" href="#cpp-netlib-http-server-api" title="Permalink to this headline">¶</a></h1>
<div class="section" id="cpp-netlib-general">
<h2>General<a class="headerlink" href="#cpp-netlib-general" title="Permalink to this headline">¶</a></h2>
<p><tt class="xref py py-mod docutils literal"><span class="pre">cpp-netlib</span></tt> includes and implements two distinct HTTP server
implementations that you can use and embed in your own applications. Both HTTP
Server implementations:</p>
<blockquote>
<div><ul class="simple">
<li><strong>Cannot be copied.</strong> This means you may have to store instances of the HTTP
Server in dynamic memory if you intend to use them as function parameters or
pass them around in smart pointers of by reference.</li>
<li><strong>Assume that requests made are independent of each other.</strong> None of the
HTTP Server implementations support request pipelining (yet) so a single
connection only deals with a single request.</li>
<li><strong>Are header-only and are compiled-into your application.</strong> Future releases
in case you want to upgrade the implementation you are using in your
application will be distributed as header-only implementations, which means
you have to re-compile your application to use a newer version of the
implementations.</li>
</div></blockquote>
<p>The HTTP Servers have different semantics, and in some cases require different
APIs from the supplied template parameters.</p>
<div class="section" id="cpp-netlib-implementations">
<h2>Implementations<a class="headerlink" href="#cpp-netlib-implementations" title="Permalink to this headline">¶</a></h2>
<p>There are two different user-facing template classes that differentiate the
<a class="reference internal" href="#synchronous-servers">Synchronous Servers</a> from the <a class="reference internal" href="#asynchronous-servers">Asynchronous Servers</a>. Both templates take a
single template parameter named <tt class="docutils literal"><span class="pre">Handler</span></tt> which describes the type of the
Handler function object.</p>
<p>There are two different Handler concepts, one concept for <a class="reference internal" href="#synchronous-servers">Synchronous Servers</a>
and another for <cite>Asynchronous Servers</cite>.</p>
<p>The SynchronousHandler concept for <a class="reference internal" href="#synchronous-servers">Synchronous Servers</a> is described by the
following table:</p>
<hr class="docutils" />
<p><strong>Legend:</strong></p>
<dl class="docutils">
<dd>The Handler type.</dd>
<dd>An instance of H.</dd>
<dt>Req</dt>
<dd>A type that models the Request Concept.</dd>
<dt>Res</dt>
<dd>A type that models the Response Concept.</dd>
<dt>req</dt>
<dd>An instance of Req.</dd>
<dt>res</dt>
<dd>An instance of Res.</dd>
<table border="1" class="docutils">
<col width="21%" />
<col width="17%" />
<col width="61%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head">Construct</th>
<th class="head">Return Type</th>
<th class="head">Description</th>
<tbody valign="top">
<tr><td><tt class="docutils literal"><span class="pre">h(req,res)</span></tt></td>
<td><tt class="docutils literal"><span class="pre">void</span></tt></td>
<td>Handle the request; res is passed in as a
non-const lvalue, which represents the
response to be returned to the client
performing the request.</td>
<p>More information about the internals of the <a class="reference internal" href="#synchronous-servers">Synchronous Servers</a> can be found
in the following section.</p>
<p>The AsynchronousHandler concept for <a class="reference internal" href="#asynchronous-servers">Asynchronous Servers</a> is described by the
following table:</p>
<hr class="docutils" />
<p><strong>Legend:</strong></p>
<dl class="docutils">
<dd>The Handler type.</dd>
<dd>An instance of H.</dd>
<dt>Req</dt>
<dd>A type that models the Request Concept.</dd>
<dt>ConnectionPtr</dt>
<dd>A type that models the Connection Pointer Concept.</dd>
<dt>req</dt>
<dd>An instance of Req.</dd>
<dt>conn</dt>
<dd>An instance of ConncetionPtr.</dd>
<table border="1" class="docutils">
<col width="24%" />
<col width="17%" />
<col width="59%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head">Construct</th>
<th class="head">Return Type</th>
<th class="head">Description</th>
<tbody valign="top">
<tr><td><tt class="docutils literal"><span class="pre">h(req,</span> <span class="pre">conn)</span></tt></td>
<td><tt class="docutils literal"><span class="pre">void</span></tt></td>
<td>Handle the request; conn is a shared
pointer which exposes functions for
writing to and reading from the connection.</td>
<p>More information about the internals of the <a class="reference internal" href="#asynchronous-servers">Asynchronous Servers</a> can be found
in the following section.</p>
<div class="section" id="cpp-netlib-synchronous-servers">
<h2>Synchronous Servers<a class="headerlink" href="#cpp-netlib-synchronous-servers" title="Permalink to this headline">¶</a></h2>
<p>The synchronous server implementation is represented by the template <tt class="docutils literal"><span class="pre">server</span></tt>
in namespace <tt class="docutils literal"><span class="pre">boost::network::http</span></tt>. The <tt class="docutils literal"><span class="pre">server</span></tt> template takes in a single
template parameter named <tt class="docutils literal"><span class="pre">Handler</span></tt> which models the SynchronousHandler
concept (described above).</p>
<p>An instance of Handler is taken in by reference to the constructor of the HTTP
server. This means the Handler is not copied around and only a single instance
of the handler is used for all connections and requests performed against the
HTTP server.</p>
<div class="admonition warning">
<p class="first admonition-title">Warning</p>
<p class="last">It is important to note that the HTTP server does not implement any
locking upon invoking the Handler. In case you have any state in the Handler
that will be associated with the synchronous server, you would have to
implement your own synchronization internal to the Handler implementation.
This matters especially if you run the synchronous server in multiple
threads.</p>
<p>The general pattern of usage for the HTTP Server template is shown below:</p>
<div class="highlight-c++"><div class="highlight"><pre><span class="k">struct</span> <span class="n">handler</span><span class="p">;</span>
<span class="k">typedef</span> <span class="n">boost</span><span class="o">::</span><span class="n">network</span><span class="o">::</span><span class="n">http</span><span class="o">::</span><span class="n">server</span><span class="o">&lt;</span><span class="n">handler</span><span class="o">&gt;</span> <span class="n">http_server</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">handler</span> <span class="p">{</span>
    <span class="kt">void</span> <span class="k">operator</span><span class="p">()(</span>
        <span class="n">http_server</span><span class="o">::</span><span class="n">request</span> <span class="k">const</span> <span class="o">&amp;</span> <span class="n">req</span><span class="p">,</span>
        <span class="n">http_server</span><span class="o">::</span><span class="n">response</span> <span class="o">&amp;</span> <span class="n">res</span>
    <span class="p">)</span> <span class="p">{</span>
        <span class="c1">// do something, and then edit the res object here.</span>
    <span class="p">}</span>
<span class="p">};</span>
</pre></div>
<p>More information about the actual HTTP Server API follows in the next section.
It is important to understand that the HTTP Server is actually embedded in your
application, which means you can expose almost all your application logic
through the Handler type, which you can also initialize appropriately.</p>
<div class="section" id="cpp-netlib-api-documentation">
<h3>API Documentation<a class="headerlink" href="#cpp-netlib-api-documentation" title="Permalink to this headline">¶</a></h3>
<p>The following sections assume that the following file has been included:</p>
<div class="highlight-c++"><div class="highlight"><pre><span class="cp">#include &lt;boost/network/include/http/server.hpp&gt;</span>
</pre></div>
<p>And that the following typedef&#8217;s have been put in place:</p>
<div class="highlight-c++"><div class="highlight"><pre><span class="k">struct</span> <span class="n">handler_type</span><span class="p">;</span>
<span class="k">typedef</span> <span class="n">boost</span><span class="o">::</span><span class="n">network</span><span class="o">::</span><span class="n">http</span><span class="o">::</span><span class="n">server</span><span class="o">&lt;</span><span class="n">handler_type</span><span class="o">&gt;</span> <span class="n">http_server</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">handler_type</span> <span class="p">{</span>
    <span class="kt">void</span> <span class="k">operator</span><span class="p">()(</span>
        <span class="n">http_server</span><span class="o">::</span><span class="n">request</span> <span class="k">const</span> <span class="o">&amp;</span> <span class="n">request</span><span class="p">,</span>
        <span class="n">http_server</span><span class="o">::</span><span class="n">response</span> <span class="o">&amp;</span> <span class="n">response</span>
    <span class="p">)</span> <span class="p">{</span>
        <span class="c1">// do something here</span>
    <span class="p">}</span>
<span class="p">};</span>
</pre></div>
<div class="section" id="cpp-netlib-constructor">
<h4>Constructor<a class="headerlink" href="#cpp-netlib-constructor" title="Permalink to this headline">¶</a></h4>
<dl class="docutils">
<dt><tt class="docutils literal"><span class="pre">http_server(address,</span> <span class="pre">port,</span> <span class="pre">handler)</span></tt></dt>
<dd>Construct an HTTP Server instance, passing in the address and port as
<tt class="docutils literal"><span class="pre">std::string</span> <span class="pre">const</span> <span class="pre">&amp;</span></tt> and handler being of type <tt class="docutils literal"><span class="pre">handler_type</span></tt> but
passed in as an lvalue reference.</dd>
<dt><tt class="docutils literal"><span class="pre">template</span> <span class="pre">&lt;class</span> <span class="pre">ArgPack&gt;</span> <span class="pre">client(ArgPack</span> <span class="pre">const</span> <span class="pre">&amp;</span> <span class="pre">args)</span></tt></dt>
<dd>Pass in an argument pack. See supported parameters in the table below.</dd>
<table border="1" class="docutils">
<col width="15%" />
<col width="26%" />
<col width="60%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head">Parameter Name</th>
<th class="head">Type</th>
<th class="head">Description</th>
<tbody valign="top">
<tr><td>_address</td>
<td>string_type</td>
<td>The hostname or IP address from which the server should be bound to. This parameter is required.</td>
<tr><td>_port</td>
<td>string_type</td>
<td>The port to which the server should bind and listen to. This parameter is required.</td>
<tr><td>_handler</td>
<td><tt class="docutils literal"><span class="pre">Handler</span> <span class="pre">&amp;</span></tt></td>
<td>An lvalue reference to an instance of <tt class="docutils literal"><span class="pre">Handler</span></tt>. This parameter is required.</td>
<tr><td>_thread_pool</td>
<td><tt class="docutils literal"><span class="pre">boost::network::utils::thread_pool</span> <span class="pre">&amp;</span></tt></td>
<td>An lvalue reference to an instance of <tt class="docutils literal"><span class="pre">boost::network::utils::thread_pool</span></tt> &#8211; this is the
thread pool from where the handler is invoked. This parameter is only applicable and required
for <tt class="docutils literal"><span class="pre">async_server</span></tt> instances.</td>
<tr><td>_io_service</td>
<td><tt class="docutils literal"><span class="pre">boost::asio::io_service</span> <span class="pre">&amp;</span></tt></td>
<td>An optional lvalue to an instance of <tt class="docutils literal"><span class="pre">boost::asio::io_service</span></tt> which allows the server to use
an already-constructed <tt class="docutils literal"><span class="pre">boost::asio::io_service</span></tt> instance instead of instantiating one that it
manages.</td>
<tr><td>_reuse_address</td>
<td><tt class="docutils literal"><span class="pre">bool</span></tt></td>
<td>A boolean that specifies whether to re-use the address and port on which the server will be
bound to. This enables or disables the socket option for listener sockets. The default is
<tt class="docutils literal"><span class="pre">false</span></tt>.</td>
<tr><td>_report_aborted</td>
<td><tt class="docutils literal"><span class="pre">bool</span></tt></td>
<td>A boolean that specifies whether the listening socket should report aborted connection attempts
to the accept handler (an internal detail of cpp-netlib). This is put in place to allow for
future-proofing the code in case an optional error handler function is supported in later
releases of cpp-netlib. The default is <tt class="docutils literal"><span class="pre">false</span></tt>.</td>
<tr><td>_receive_buffer_size</td>
<td><tt class="docutils literal"><span class="pre">int</span></tt></td>
<td>The size of the socket&#8217;s receive buffer. The default is defined by Boost.Asio and is
platform-dependent.</td>
<tr><td>_send_buffer_size</td>
<td><tt class="docutils literal"><span class="pre">int</span></tt></td>
<td>The size of the socket&#8217;s send buffer. The default is defined by Boost.Asio and is
platform-dependent.</td>
<tr><td>_receive_low_watermark</td>
<td><tt class="docutils literal"><span class="pre">int</span></tt></td>
<td>The size of the socket&#8217;s low watermark for its receive buffer. The default is defined by
Boost.Asio and is platform-dependent.</td>
<tr><td>_send_buffer_size</td>
<td><tt class="docutils literal"><span class="pre">int</span></tt></td>
<td>The size of the socket&#8217;s send low watermark for its send buffer. The default is defined by
Boost.Asio and is platform-dependent.</td>
<tr><td>_non_blocking_io</td>
<td><tt class="docutils literal"><span class="pre">bool</span></tt></td>
<td>An optional bool to define whether the socket should use non-blocking I/O in case the platform
supports it. The default is <tt class="docutils literal"><span class="pre">true</span></tt>.</td>
<tr><td>_linger</td>
<td><tt class="docutils literal"><span class="pre">bool</span></tt></td>
<td>An optional bool to determine whether the socket should linger in case there&#8217;s still data to be
sent out at the time of its closing. The default is <tt class="docutils literal"><span class="pre">true</span></tt>.</td>
<tr><td>_linger_timeout</td>
<td><tt class="docutils literal"><span class="pre">int</span></tt></td>
<td>An optional int to define the timeout to wait for socket closes before it is set to linger.
The default is <tt class="docutils literal"><span class="pre">0</span></tt>.</td>
<p>To use the above supported named parameters, you&#8217;ll have code that looks like the following:</p>
<div class="highlight-c++"><div class="highlight"><pre><span class="k">using</span> <span class="k">namespace</span> <span class="n">boost</span><span class="o">::</span><span class="n">network</span><span class="o">::</span><span class="n">http</span><span class="p">;</span> <span class="c1">// parameters are in this namespace</span>
<span class="n">boost</span><span class="o">::</span><span class="n">asio</span><span class="o">::</span><span class="n">io_service</span> <span class="n">my_io_service</span><span class="p">;</span>
<span class="n">boost</span><span class="o">::</span><span class="n">network</span><span class="o">::</span><span class="n">utils</span><span class="o">::</span><span class="n">thread_pool</span> <span class="n">pool</span><span class="p">(</span><span class="mi">2</span><span class="p">);</span>
<span class="n">handler</span> <span class="n">handler_instance</span><span class="p">;</span>
<span class="n">async_server</span><span class="o">&lt;</span><span class="n">handler</span><span class="o">&gt;</span> <span class="n">instance</span><span class="p">(</span><span class="n">_address</span><span class="o">=</span><span class="s">&quot;0.0.0.0&quot;</span><span class="p">,</span> <span class="n">_port</span><span class="o">=</span><span class="s">&quot;80&quot;</span><span class="p">,</span> <span class="n">_handler</span><span class="o">=</span><span class="n">handler_instance</span><span class="p">,</span>
                               <span class="n">_io_service</span><span class="o">=</span><span class="n">my_io_service</span><span class="p">,</span> <span class="n">_thread_pool</span><span class="o">=</span><span class="n">pool</span><span class="p">,</span>
                               <span class="n">_reuse_address</span><span class="o">=</span><span class="kc">true</span><span class="p">);</span>
<span class="n">instance</span><span class="p">.</span><span class="n">run</span><span class="p">();</span>
</pre></div>
<div class="section" id="cpp-netlib-public-members">
<h4>Public Members<a class="headerlink" href="#cpp-netlib-public-members" title="Permalink to this headline">¶</a></h4>
<p>The following definitions assume that a properly constructed <tt class="docutils literal"><span class="pre">http_server</span></tt>
instance has been constructed in the following manner:</p>
<div class="highlight-c++"><div class="highlight"><pre><span class="n">handler_type</span> <span class="n">handler</span><span class="p">;</span>
<span class="n">http_server</span> <span class="n">server</span><span class="p">(</span><span class="s">&quot;127.0.0.1&quot;</span><span class="p">,</span> <span class="s">&quot;8000&quot;</span><span class="p">,</span> <span class="n">handler</span><span class="p">);</span>
</pre></div>
<dl class="docutils">
<dt><tt class="docutils literal"><span class="pre">server.run()</span></tt></dt>
<dd>Run the HTTP Server event loop. This function can be run on multiple threads
following the example:</dd>
<div class="highlight-c++"><div class="highlight"><pre><span class="n">boost</span><span class="o">::</span><span class="kr">thread</span> <span class="n">t1</span><span class="p">(</span><span class="n">boost</span><span class="o">::</span><span class="n">bind</span><span class="p">(</span><span class="o">&amp;</span><span class="n">http_server</span><span class="o">::</span><span class="n">run</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">server</span><span class="p">));</span>
<span class="n">boost</span><span class="o">::</span><span class="kr">thread</span> <span class="n">t2</span><span class="p">(</span><span class="n">boost</span><span class="o">::</span><span class="n">bind</span><span class="p">(</span><span class="o">&amp;</span><span class="n">http_server</span><span class="o">::</span><span class="n">run</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">server</span><span class="p">));</span>
<span class="n">server</span><span class="p">.</span><span class="n">run</span><span class="p">();</span>
<span class="n">t1</span><span class="p">.</span><span class="n">join</span><span class="p">();</span>
<span class="n">t2</span><span class="p">.</span><span class="n">join</span><span class="p">();</span>
</pre></div>
<dl class="docutils">
<dt><tt class="docutils literal"><span class="pre">server.stop()</span></tt></dt>
<dd>Stop the HTTP Server acceptor and wait for all pending requests to finish.</dd>
<div class="section" id="cpp-netlib-response-object">
<h4>Response Object<a class="headerlink" href="#cpp-netlib-response-object" title="Permalink to this headline">¶</a></h4>
<p>The response object has its own public member functions which can be very
helpful in certain simple situations.</p>
<dl class="docutils">
<dt><tt class="docutils literal"><span class="pre">response</span> <span class="pre">=</span> <span class="pre">http_server::response::stock_reply(status,</span> <span class="pre">body)</span></tt></dt>
<dd>Code like the above should go inside the handler&#8217;s <tt class="docutils literal"><span class="pre">operator()</span></tt> overload.
The body parameter is an <tt class="docutils literal"><span class="pre">std::string</span></tt>. The status parameter is any of
the following values from the <tt class="docutils literal"><span class="pre">http_server::response</span></tt> enum
<tt class="docutils literal"><span class="pre">status_type</span></tt>:</dd>
<div class="highlight-c++"><div class="highlight"><pre><span class="k">enum</span> <span class="n">status_type</span> <span class="p">{</span>
    <span class="n">ok</span> <span class="o">=</span> <span class="mi">200</span><span class="p">,</span>
    <span class="n">created</span> <span class="o">=</span> <span class="mi">201</span><span class="p">,</span>
    <span class="n">accepted</span> <span class="o">=</span> <span class="mi">202</span><span class="p">,</span>
    <span class="n">no_content</span> <span class="o">=</span> <span class="mi">204</span><span class="p">,</span>
    <span class="n">multiple_choices</span> <span class="o">=</span> <span class="mi">300</span><span class="p">,</span>
    <span class="n">moved_permanently</span> <span class="o">=</span> <span class="mi">301</span><span class="p">,</span>
    <span class="n">moved_temporarily</span> <span class="o">=</span> <span class="mi">302</span><span class="p">,</span>
    <span class="n">not_modified</span> <span class="o">=</span> <span class="mi">304</span><span class="p">,</span>
    <span class="n">bad_request</span> <span class="o">=</span> <span class="mi">400</span><span class="p">,</span>
    <span class="n">unauthorized</span> <span class="o">=</span> <span class="mi">401</span><span class="p">,</span>
    <span class="n">forbidden</span> <span class="o">=</span> <span class="mi">403</span><span class="p">,</span>
    <span class="n">not_found</span> <span class="o">=</span> <span class="mi">404</span><span class="p">,</span>
    <span class="n">not_supported</span> <span class="o">=</span> <span class="mi">405</span><span class="p">,</span>
    <span class="n">not_acceptable</span> <span class="o">=</span> <span class="mi">406</span><span class="p">,</span>
    <span class="n">internal_server_error</span> <span class="o">=</span> <span class="mi">500</span><span class="p">,</span>
    <span class="n">not_implemented</span> <span class="o">=</span> <span class="mi">501</span><span class="p">,</span>
    <span class="n">bad_gateway</span> <span class="o">=</span> <span class="mi">502</span><span class="p">,</span>
    <span class="n">service_unavailable</span> <span class="o">=</span> <span class="mi">503</span>
<span class="p">};</span>
</pre></div>
<p>The response object also has the following publicly accessible member values
which can be directly manipulated by the handler.</p>
<table border="1" class="docutils">
<col width="24%" />
<col width="29%" />
<col width="47%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head">Member Name</th>
<th class="head">Type</th>
<th class="head">Description</th>
<tbody valign="top">
<tr><td>status</td>
<td><tt class="docutils literal"><span class="pre">status_type</span></tt></td>
<td>The HTTP status of the response.</td>
<tr><td>headers</td>
<td><tt class="docutils literal"><span class="pre">vector&lt;header&gt;</span></tt></td>
<td>Vector of headers. <a class="footnote-reference" href="#id3" id="id1">[1]</a></td>
<tr><td>content</td>
<td><tt class="docutils literal"><span class="pre">string_type</span></tt> <a class="footnote-reference" href="#id4" id="id2">[2]</a></td>
<td>The contents of the response.</td>
<table class="docutils footnote" frame="void" id="id3" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#id1">[1]</a></td><td>A header is a struct of type
<tt class="docutils literal"><span class="pre">response_header&lt;http::tags::http_server&gt;</span></tt>. An instance always has the
members <tt class="docutils literal"><span class="pre">name</span></tt> and <tt class="docutils literal"><span class="pre">value</span></tt> both of which are of type <tt class="docutils literal"><span class="pre">string_type</span></tt>.</td></tr>
<table class="docutils footnote" frame="void" id="id4" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#id2">[2]</a></td><td><tt class="docutils literal"><span class="pre">string_type</span></tt> is
<tt class="docutils literal"><span class="pre">boost::network::string&lt;http::tags::http_server&gt;::type</span></tt>.</td></tr>
<div class="section" id="cpp-netlib-asynchronous-servers">
<h2>Asynchronous Servers<a class="headerlink" href="#cpp-netlib-asynchronous-servers" title="Permalink to this headline">¶</a></h2>
<p>The asynchronous server implementation is significantly different to the
synchronous server implementation in three ways:</p>
<blockquote>
<div><ol class="arabic simple">
<li><strong>The Handler instance is invoked asynchronously</strong>. This means the I/O
thread used to handle network-related events are free to handle only the
I/O related events. This enables the server to scale better as to the
number of concurrent connections it can handle.</li>
<li><strong>The Handler is able to schedule asynchronous actions on the thread pool
associated with the server.</strong> This allows handlers to perform multiple
asynchronous computations that later on perform writes to the connection.</li>
<li><strong>The Handler is able to control the (asynchronous) writes to and reads from
the HTTP connection.</strong> Because the connection is available to the Handler,
that means it can write out chunks of data at a time or stream data through
the connection continuously.</li>
</div></blockquote>
<p>The asynchronous server is meant to allow for better scalability in terms of the
number of concurrent connections and for performing asynchronous actions within
the handlers. If your applacation does not need to write out information
asynchronously or perform potentially long computations, then the synchronous
server gives a generally better performance profile than the asynchronous
server.</p>
<p>The asynchronous server implementation is available from a single user-facing
template named <tt class="docutils literal"><span class="pre">async_server</span></tt>. This template takes in a single template
parameter which is the type of the Handler to be called once a request has been
parsed from a connection.</p>
<p>An instance of Handler is taken as a reference to the constructor similar to the
synchronous server implementation.</p>
<div class="admonition warning">
<p class="first admonition-title">Warning</p>
<p class="last">The asynchronous server implementation, like the synchronous server
implementation, does not perform any synchronization on the calls to the
Handler invocation. This means if your handler contains or maintains internal
state, you are responsible for implementing your own synchronization on
accesses to the internal state of the Handler.</p>
<p>The general pattern for using the <tt class="docutils literal"><span class="pre">async_server</span></tt> template is shown below:</p>
<div class="highlight-c++"><div class="highlight"><pre><span class="k">struct</span> <span class="n">handler</span><span class="p">;</span>
<span class="k">typedef</span> <span class="n">boost</span><span class="o">::</span><span class="n">network</span><span class="o">::</span><span class="n">http</span><span class="o">::</span><span class="n">async_server</span><span class="o">&lt;</span><span class="n">handler</span><span class="o">&gt;</span> <span class="n">http_server</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">handler</span> <span class="p">{</span>
    <span class="kt">void</span> <span class="k">operator</span><span class="p">()(</span>
        <span class="n">http_server</span><span class="o">::</span><span class="n">request</span> <span class="k">const</span> <span class="o">&amp;</span> <span class="n">req</span><span class="p">,</span>
        <span class="n">http_server</span><span class="o">::</span><span class="n">connection_ptr</span> <span class="n">connection</span>
    <span class="p">)</span> <span class="p">{</span>
        <span class="c1">// handle the request here, and use the connection to</span>
        <span class="c1">// either read more data or write data out to the client</span>
    <span class="p">}</span>
<span class="p">};</span>
</pre></div>
<div class="section" id="cpp-netlib-id5">
<h3>API Documentation<a class="headerlink" href="#cpp-netlib-id5" title="Permalink to this headline">¶</a></h3>
<p>The following sections assume that the following file has been included:</p>
<div class="highlight-c++"><div class="highlight"><pre><span class="cp">#include &lt;boost/network/include/http/server.hpp&gt;</span>
<span class="cp">#include &lt;boost/network/utils/thread_pool.hpp&gt;</span>
</pre></div>
<p>And that the following typedef&#8217;s have been put in place:</p>
<div class="highlight-c++"><div class="highlight"><pre><span class="k">struct</span> <span class="n">handler_type</span><span class="p">;</span>
<span class="k">typedef</span> <span class="n">boost</span><span class="o">::</span><span class="n">network</span><span class="o">::</span><span class="n">http</span><span class="o">::</span><span class="n">server</span><span class="o">&lt;</span><span class="n">handler_type</span><span class="o">&gt;</span> <span class="n">http_server</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">handler_type</span> <span class="p">{</span>
    <span class="kt">void</span> <span class="k">operator</span><span class="p">()(</span>
        <span class="n">http_server</span><span class="o">::</span><span class="n">request</span> <span class="k">const</span> <span class="o">&amp;</span> <span class="n">request</span><span class="p">,</span>
        <span class="n">http_server</span><span class="o">::</span><span class="n">connection_ptr</span> <span class="n">connection</span>
    <span class="p">)</span> <span class="p">{</span>
        <span class="c1">// do something here</span>
    <span class="p">}</span>
<span class="p">};</span>
</pre></div>
<div class="section" id="cpp-netlib-id6">
<h4>Constructor<a class="headerlink" href="#cpp-netlib-id6" title="Permalink to this headline">¶</a></h4>
<dl class="docutils">
<dt><tt class="docutils literal"><span class="pre">http_server(address,</span> <span class="pre">port,</span> <span class="pre">handler,</span> <span class="pre">thread_pool)</span></tt></dt>
<dd>Construct an HTTP Server instance, passing in the address and port as
<tt class="docutils literal"><span class="pre">std::string</span> <span class="pre">const</span> <span class="pre">&amp;</span></tt> and handler being of type <tt class="docutils literal"><span class="pre">handler_type</span></tt> but
passed in as an lvalue reference. The <tt class="docutils literal"><span class="pre">thread_pool</span></tt> parameter is an
instance of <tt class="docutils literal"><span class="pre">boost::network::utils::thread_pool</span></tt> that has been previously
instantiated.</dd>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">The <tt class="docutils literal"><span class="pre">boost::network::utils::thread_pool</span></tt> has a single constructor
parameter which is the number of threads to run the thread pool.</p>
<div class="section" id="cpp-netlib-id7">
<h4>Public Members<a class="headerlink" href="#cpp-netlib-id7" title="Permalink to this headline">¶</a></h4>
<p>The following definitions assume that a properly constructed <tt class="docutils literal"><span class="pre">http_server</span></tt>
instance has been constructed in the following manner:</p>
<div class="highlight-c++"><div class="highlight"><pre><span class="n">handler_type</span> <span class="n">handler</span><span class="p">;</span>
<span class="n">boost</span><span class="o">::</span><span class="n">network</span><span class="o">::</span><span class="n">utils</span><span class="o">::</span><span class="n">thread_pool</span> <span class="n">thread_pool</span><span class="p">(</span><span class="mi">2</span><span class="p">);</span>
<span class="n">http_server</span> <span class="n">server</span><span class="p">(</span><span class="s">&quot;127.0.0.1&quot;</span><span class="p">,</span> <span class="s">&quot;8000&quot;</span><span class="p">,</span> <span class="n">handler</span><span class="p">,</span> <span class="n">thread_pool</span><span class="p">);</span>
</pre></div>
<dl class="docutils">
<dt><tt class="docutils literal"><span class="pre">server.run()</span></tt></dt>
<dd>Run the HTTP Server event loop. This function can be run on multiple threads
following the example:</dd>
<div class="highlight-c++"><div class="highlight"><pre><span class="n">boost</span><span class="o">::</span><span class="kr">thread</span> <span class="n">t1</span><span class="p">(</span><span class="n">boost</span><span class="o">::</span><span class="n">bind</span><span class="p">(</span><span class="o">&amp;</span><span class="n">http_server</span><span class="o">::</span><span class="n">run</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">server</span><span class="p">));</span>
<span class="n">boost</span><span class="o">::</span><span class="kr">thread</span> <span class="n">t2</span><span class="p">(</span><span class="n">boost</span><span class="o">::</span><span class="n">bind</span><span class="p">(</span><span class="o">&amp;</span><span class="n">http_server</span><span class="o">::</span><span class="n">run</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">server</span><span class="p">));</span>
<span class="n">server</span><span class="p">.</span><span class="n">run</span><span class="p">();</span>
<span class="n">t1</span><span class="p">.</span><span class="n">join</span><span class="p">();</span>
<span class="n">t2</span><span class="p">.</span><span class="n">join</span><span class="p">();</span>
</pre></div>
<dl class="docutils">
<dt><tt class="docutils literal"><span class="pre">server.stop()</span></tt></dt>
<dd>Stop the HTTP Server acceptor and wait for all pending requests to finish.</dd>
<div class="section" id="cpp-netlib-connection-object">
<h4>Connection Object<a class="headerlink" href="#cpp-netlib-connection-object" title="Permalink to this headline">¶</a></h4>
<p>The connection object has its own public member functions which will be the
primary means for reading from and writing to the connection.</p>
<dl class="docutils">
<dt><tt class="docutils literal"><span class="pre">template</span> <span class="pre">&lt;class</span> <span class="pre">Range&gt;</span> <span class="pre">write(Range</span> <span class="pre">range)</span></tt></dt>
<dd><p class="first">The connection object exposes a function <tt class="docutils literal"><span class="pre">write</span></tt> that can be given a
parameter that adheres to the <a class="reference external" href="http://www.boost.org/libs/range">Boost.Range</a> <tt class="docutils literal"><span class="pre">Single</span> <span class="pre">Pass</span> <span class="pre">Range</span></tt> Concept.
The write function, although it looks synchronous, starts of a series of
asynchronous writes to the connection as soon as the range is serialized to
appropriately sized buffers.</p>
<p class="last">To use this in your handler, it would look something like this:</p>
<div class="highlight-c++"><div class="highlight"><pre><span class="n">connection</span><span class="o">-&gt;</span><span class="n">write</span><span class="p">(</span><span class="s">&quot;Hello, world!&quot;</span><span class="p">);</span>
<span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">sample</span> <span class="o">=</span> <span class="s">&quot;I have a string!&quot;</span><span class="p">;</span>
<span class="n">connection</span><span class="o">-&gt;</span><span class="n">write</span><span class="p">(</span><span class="n">sample</span><span class="p">);</span>
</pre></div>
<dl class="docutils">
<dt><tt class="docutils literal"><span class="pre">template</span> <span class="pre">&lt;class</span> <span class="pre">Range,</span> <span class="pre">class</span> <span class="pre">Callback&gt;</span> <span class="pre">void</span> <span class="pre">write(Range</span> <span class="pre">range,</span> <span class="pre">Callback</span> <span class="pre">callback)</span></tt></dt>
<dd>The connection object also exposes a function <tt class="docutils literal"><span class="pre">write</span></tt> that can be given a
parameter that adheres to the <a class="reference external" href="http://www.boost.org/libs/range">Boost.Range</a> <tt class="docutils literal"><span class="pre">Single</span> <span class="pre">Pass</span> <span class="pre">Range</span></tt> Concept, as
well as a Callback function that returns <tt class="docutils literal"><span class="pre">void</span></tt> and takes a
<tt class="docutils literal"><span class="pre">boost::system::error_code</span></tt> as a parameter. This overload of <tt class="docutils literal"><span class="pre">write</span></tt> is
useful for writing streaming applications that send out chunks of data at a
time, or for writing data that may not all fit in memory right away.</dd>
<dt><tt class="docutils literal"><span class="pre">template</span> <span class="pre">&lt;class</span> <span class="pre">ReadCallback&gt;</span> <span class="pre">void</span> <span class="pre">read(ReadCallback</span> <span class="pre">callback)</span></tt></dt>
<dd><p class="first">The connection object has a function <tt class="docutils literal"><span class="pre">read</span></tt> which can be used to read more
information from the connection. This <tt class="docutils literal"><span class="pre">read</span></tt> function takes in a callback
that can be assigned to a <a class="reference external" href="http://www.boost.org/libs/function">Boost.Function</a> with the signature
<tt class="docutils literal"><span class="pre">void(input_range,error_code,size_t,connection_ptr)</span></tt>. The following list
shows what the types actually mean:</p>
<blockquote>
<div><ul class="simple">
<li><strong>input_range</strong> &#8211; <tt class="docutils literal"><span class="pre">boost::iterator_range&lt;char</span> <span class="pre">const</span> <span class="pre">*&gt;</span></tt> : The range
that denotes the data read from the connection.</li>
<li><strong>error_code</strong> &#8211; <tt class="docutils literal"><span class="pre">boost::system::error_code</span></tt> : The error code if
there were any errors encountered from the read.</li>
<li><strong>size_t</strong> &#8211; <tt class="docutils literal"><span class="pre">std::size_t</span></tt> : The number of bytes transferred.</li>
<li><strong>connection_ptr</strong> &#8211; <tt class="docutils literal"><span class="pre">http_server::connection_ptr</span></tt> : A handle to the
current connection, so that it is kept alive at the time of the read
callback invocation.</li>
</div></blockquote>
<p class="last">This interface is useful when doing reads of uploaded data that can be
potentially large and may not fit in memory. The read handler is then
responsible for dealing with the chunks of data available from the
connection.</p>
<dt><tt class="docutils literal"><span class="pre">void</span> <span class="pre">set_status(status_t</span> <span class="pre">new_status)</span></tt></dt>
<dd>The <tt class="docutils literal"><span class="pre">set_status</span></tt> function takes a parameter of type <tt class="docutils literal"><span class="pre">status_t</span></tt> which is
an enum type nested in <tt class="docutils literal"><span class="pre">http_status::connection</span></tt> which is given in the
following code listing.</dd>
<div class="highlight-c++"><div class="highlight"><pre><span class="k">enum</span> <span class="n">status_t</span> <span class="p">{</span>
    <span class="n">ok</span> <span class="o">=</span> <span class="mi">200</span>
    <span class="p">,</span> <span class="n">created</span> <span class="o">=</span> <span class="mi">201</span>
    <span class="p">,</span> <span class="n">accepted</span> <span class="o">=</span> <span class="mi">202</span>
    <span class="p">,</span> <span class="n">no_content</span> <span class="o">=</span> <span class="mi">204</span>
    <span class="p">,</span> <span class="n">multiple_choices</span> <span class="o">=</span> <span class="mi">300</span>
    <span class="p">,</span> <span class="n">moved_permanently</span> <span class="o">=</span> <span class="mi">301</span>
    <span class="p">,</span> <span class="n">moved_temporarily</span> <span class="o">=</span> <span class="mi">302</span>
    <span class="p">,</span> <span class="n">not_modified</span> <span class="o">=</span> <span class="mi">304</span>
    <span class="p">,</span> <span class="n">bad_request</span> <span class="o">=</span> <span class="mi">400</span>
    <span class="p">,</span> <span class="n">unauthorized</span> <span class="o">=</span> <span class="mi">401</span>
    <span class="p">,</span> <span class="n">forbidden</span> <span class="o">=</span> <span class="mi">403</span>
    <span class="p">,</span> <span class="n">not_found</span> <span class="o">=</span> <span class="mi">404</span>
    <span class="p">,</span> <span class="n">not_supported</span> <span class="o">=</span> <span class="mi">405</span>
    <span class="p">,</span> <span class="n">not_acceptable</span> <span class="o">=</span> <span class="mi">406</span>
    <span class="p">,</span> <span class="n">internal_server_error</span> <span class="o">=</span> <span class="mi">500</span>
    <span class="p">,</span> <span class="n">not_implemented</span> <span class="o">=</span> <span class="mi">501</span>
    <span class="p">,</span> <span class="n">bad_gateway</span> <span class="o">=</span> <span class="mi">502</span>
    <span class="p">,</span> <span class="n">service_unavailable</span> <span class="o">=</span> <span class="mi">503</span>
<span class="p">};</span>
</pre></div>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">You may set and re-set the status several times as long as you have
not set the headers or sent data through the connection. If you do this after
data has already been set, the function will throw an instance of
<tt class="docutils literal"><span class="pre">std::logic_error</span></tt>.</p>
<dl class="docutils">
<dt><tt class="docutils literal"><span class="pre">template</span> <span class="pre">&lt;class</span> <span class="pre">Range&gt;</span> <span class="pre">void</span> <span class="pre">set_headers(Range</span> <span class="pre">range)</span></tt></dt>
<dd><p class="first">The <tt class="docutils literal"><span class="pre">set_headers</span></tt> function takes a Single Pass Range of
<tt class="docutils literal"><span class="pre">boost::network::http::response_header&lt;http::tags::http_async_server&gt;</span></tt>
instances and linearizes them to a buffer with at most
<tt class="docutils literal"><span class="pre">BOOST_NETWORK_HTTP_SERVER_CONNECTION_HEADER_BUFFER_MAX_SIZE</span></tt> and
immediately schedules an asynchronous write once that is done.</p>
<p class="last">The function throws an instance of <tt class="docutils literal"><span class="pre">std::logic_error</span></tt> if you try to set
the headers for a connection more than once.</p>
          </div>
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  <h3><a href="../contents.html">Table Of Contents</a></h3>
<li><a class="reference internal" href="#">HTTP Server API</a><ul>
<li><a class="reference internal" href="#general">General</a></li>
<li><a class="reference internal" href="#implementations">Implementations</a></li>
<li><a class="reference internal" href="#synchronous-servers">Synchronous Servers</a><ul>
<li><a class="reference internal" href="#api-documentation">API Documentation</a><ul>
<li><a class="reference internal" href="#constructor">Constructor</a></li>
<li><a class="reference internal" href="#public-members">Public Members</a></li>
<li><a class="reference internal" href="#response-object">Response Object</a></li>
<li><a class="reference internal" href="#asynchronous-servers">Asynchronous Servers</a><ul>
<li><a class="reference internal" href="#id5">API Documentation</a><ul>
<li><a class="reference internal" href="#id6">Constructor</a></li>
<li><a class="reference internal" href="#id7">Public Members</a></li>
<li><a class="reference internal" href="#connection-object">Connection Object</a></li>
  <h3>Browse</h3>
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