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<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.ResolverService"></a><a class="link" href="ResolverService.html" title="Resolver service requirements">Resolver service requirements</a>
</h3></div></div></div>
<p>
A resolver service must meet the requirements for an <a class="link" href="IoObjectService.html" title="I/O object service requirements">I/O
object service</a>, as well as the additional requirements listed below.
</p>
<p>
In the table below, <code class="computeroutput"><span class="identifier">X</span></code> denotes
a resolver service class for protocol <code class="computeroutput"><span class="identifier">InternetProtocol</span></code>,
<code class="computeroutput"><span class="identifier">a</span></code> denotes a value of type
<code class="computeroutput"><span class="identifier">X</span></code>, <code class="computeroutput"><span class="identifier">b</span></code>
denotes a value of type <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">implementation_type</span></code>,
<code class="computeroutput"><span class="identifier">q</span></code> denotes a value of type
<code class="computeroutput"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">basic_resolver_query</span><span class="special"><</span><span class="identifier">InternetProtocol</span><span class="special">></span></code>,
<code class="computeroutput"><span class="identifier">e</span></code> denotes a value of type
<code class="computeroutput"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">basic_endpoint</span><span class="special"><</span><span class="identifier">InternetProtocol</span><span class="special">></span></code>,
<code class="computeroutput"><span class="identifier">ec</span></code> denotes a value of type
<code class="computeroutput"><span class="identifier">error_code</span></code>, and <code class="computeroutput"><span class="identifier">h</span></code> denotes a value meeting <a class="link" href="ResolveHandler.html" title="Resolve handler requirements"><code class="computeroutput"><span class="identifier">ResolveHandler</span></code></a> requirements.
</p>
<div class="table">
<a name="id699892"></a><p class="title"><b>Table 22. ResolverService requirements</b></p>
<div class="table-contents"><table class="table" summary="ResolverService requirements">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
expression
</p>
</th>
<th>
<p>
return type
</p>
</th>
<th>
<p>
assertion/note\npre/post-condition
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">destroy</span><span class="special">(</span><span class="identifier">b</span><span class="special">);</span></code>
</p>
</td>
<td>
</td>
<td>
<p>
From <a class="link" href="IoObjectService.html" title="I/O object service requirements">IoObjectService</a>
requirements. Implicitly cancels asynchronous resolve operations,
as if by calling <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">cancel</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">)</span></code>.
</p>
</td>
</tr>
<tr>
<td>
<p>
</p>
<pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">cancel</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
</pre>
<p>
</p>
</td>
<td>
<p>
<code class="computeroutput"><span class="identifier">error_code</span></code>
</p>
</td>
<td>
<p>
Causes any outstanding asynchronous resolve operations to complete
as soon as possible. Handlers for cancelled operations shall be
passed the error code <code class="computeroutput"><span class="identifier">error</span><span class="special">::</span><span class="identifier">operation_aborted</span></code>.
</p>
</td>
</tr>
<tr>
<td>
<p>
</p>
<pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">resolve</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">q</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
</pre>
<p>
</p>
</td>
<td>
<p>
</p>
<pre class="programlisting"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">basic_resolver_iterator</span><span class="special"><</span>
<span class="identifier">InternetProtocol</span><span class="special">></span>
</pre>
<p>
</p>
</td>
<td>
<p>
On success, returns an iterator <code class="computeroutput"><span class="identifier">i</span></code>
such that <code class="computeroutput"><span class="identifier">i</span> <span class="special">!=</span>
<span class="identifier">ip</span><span class="special">::</span><span class="identifier">basic_resolver_iterator</span><span class="special"><</span><span class="identifier">InternetProtocol</span><span class="special">>()</span></code>.
Otherwise returns <code class="computeroutput"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">basic_resolver_iterator</span><span class="special"><</span><span class="identifier">InternetProtocol</span><span class="special">>()</span></code>.
</p>
</td>
</tr>
<tr>
<td>
<p>
</p>
<pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">async_resolve</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">q</span><span class="special">,</span> <span class="identifier">h</span><span class="special">);</span>
</pre>
<p>
</p>
</td>
<td>
</td>
<td>
<p>
Initiates an asynchronous resolve operation that is performed via
the <code class="computeroutput"><span class="identifier">io_service</span></code>
object <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">io_service</span><span class="special">()</span></code>
and behaves according to <a class="link" href="asynchronous_operations.html" title="Requirements on asynchronous operations">asynchronous
operation</a> requirements.\n \n If the operation completes
successfully, the <code class="computeroutput"><span class="identifier">ResolveHandler</span></code>
object <code class="computeroutput"><span class="identifier">h</span></code> shall
be invoked with an iterator object <code class="computeroutput"><span class="identifier">i</span></code>
such that the condition <code class="computeroutput"><span class="identifier">i</span>
<span class="special">!=</span> <span class="identifier">ip</span><span class="special">::</span><span class="identifier">basic_resolver_iterator</span><span class="special"><</span><span class="identifier">InternetProtocol</span><span class="special">>()</span></code> holds. Otherwise it is invoked
with <code class="computeroutput"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">basic_resolver_iterator</span><span class="special"><</span><span class="identifier">InternetProtocol</span><span class="special">>()</span></code>.
</p>
</td>
</tr>
<tr>
<td>
<p>
</p>
<pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">resolve</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">e</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
</pre>
<p>
</p>
</td>
<td>
<p>
</p>
<pre class="programlisting"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">basic_resolver_iterator</span><span class="special"><</span>
<span class="identifier">InternetProtocol</span><span class="special">></span>
</pre>
<p>
</p>
</td>
<td>
<p>
On success, returns an iterator <code class="computeroutput"><span class="identifier">i</span></code>
such that <code class="computeroutput"><span class="identifier">i</span> <span class="special">!=</span>
<span class="identifier">ip</span><span class="special">::</span><span class="identifier">basic_resolver_iterator</span><span class="special"><</span><span class="identifier">InternetProtocol</span><span class="special">>()</span></code>.
Otherwise returns <code class="computeroutput"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">basic_resolver_iterator</span><span class="special"><</span><span class="identifier">InternetProtocol</span><span class="special">>()</span></code>.
</p>
</td>
</tr>
<tr>
<td>
<p>
</p>
<pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">async_resolve</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">e</span><span class="special">,</span> <span class="identifier">h</span><span class="special">);</span>
</pre>
<p>
</p>
</td>
<td>
</td>
<td>
<p>
Initiates an asynchronous resolve operation that is performed via
the <code class="computeroutput"><span class="identifier">io_service</span></code>
object <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">io_service</span><span class="special">()</span></code>
and behaves according to <a class="link" href="asynchronous_operations.html" title="Requirements on asynchronous operations">asynchronous
operation</a> requirements.\n \n If the operation completes
successfully, the <code class="computeroutput"><span class="identifier">ResolveHandler</span></code>
object <code class="computeroutput"><span class="identifier">h</span></code> shall
be invoked with an iterator object <code class="computeroutput"><span class="identifier">i</span></code>
such that the condition <code class="computeroutput"><span class="identifier">i</span>
<span class="special">!=</span> <span class="identifier">ip</span><span class="special">::</span><span class="identifier">basic_resolver_iterator</span><span class="special"><</span><span class="identifier">InternetProtocol</span><span class="special">>()</span></code> holds. Otherwise it is invoked
with <code class="computeroutput"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">basic_resolver_iterator</span><span class="special"><</span><span class="identifier">InternetProtocol</span><span class="special">>()</span></code>.
</p>
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<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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