File: tutdaytime6.html

package info (click to toggle)
boost1.55 1.55.0%2Bdfsg-3
  • links: PTS, VCS
  • area: main
  • in suites: jessie, jessie-kfreebsd
  • size: 487,824 kB
  • ctags: 673,349
  • sloc: cpp: 2,098,430; xml: 106,036; ansic: 46,744; python: 32,427; sh: 11,864; cs: 2,121; asm: 1,640; makefile: 984; perl: 714; yacc: 456; php: 132; fortran: 43; sql: 13; csh: 6
file content (189 lines) | stat: -rw-r--r-- 17,577 bytes parent folder | download 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
 
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<title>Daytime.6 - An asynchronous UDP daytime server</title>
<link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.78.1">
<link rel="home" href="../../boost_asio.html" title="Boost.Asio">
<link rel="up" href="../tutorial.html" title="Tutorial">
<link rel="prev" href="tutdaytime5/src.html" title="Source listing for Daytime.5">
<link rel="next" href="tutdaytime6/src.html" title="Source listing for Daytime.6">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr>
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../boost.png"></td>
<td align="center"><a href="../../../../index.html">Home</a></td>
<td align="center"><a href="../../../../libs/libraries.htm">Libraries</a></td>
<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
<td align="center"><a href="../../../../more/index.htm">More</a></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="tutdaytime5/src.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../tutorial.html"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../boost_asio.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="tutdaytime6/src.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="boost_asio.tutorial.tutdaytime6"></a><a class="link" href="tutdaytime6.html" title="Daytime.6 - An asynchronous UDP daytime server">Daytime.6 - An asynchronous
      UDP daytime server</a>
</h3></div></div></div>
<h5>
<a name="boost_asio.tutorial.tutdaytime6.h0"></a>
        <span class="phrase"><a name="boost_asio.tutorial.tutdaytime6.the_main___function"></a></span><a class="link" href="tutdaytime6.html#boost_asio.tutorial.tutdaytime6.the_main___function">The
        main() function</a>
      </h5>
<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
<span class="special">{</span>
  <span class="keyword">try</span>
  <span class="special">{</span>
</pre>
<p>
        Create a server object to accept incoming client requests, and run the <a class="link" href="../reference/io_service.html" title="io_service">io_service</a> object.
      </p>
<pre class="programlisting">    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">io_service</span> <span class="identifier">io_service</span><span class="special">;</span>
    <span class="identifier">udp_server</span> <span class="identifier">server</span><span class="special">(</span><span class="identifier">io_service</span><span class="special">);</span>
    <span class="identifier">io_service</span><span class="special">.</span><span class="identifier">run</span><span class="special">();</span>
  <span class="special">}</span>
  <span class="keyword">catch</span> <span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">exception</span><span class="special">&amp;</span> <span class="identifier">e</span><span class="special">)</span>
  <span class="special">{</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cerr</span> <span class="special">&lt;&lt;</span> <span class="identifier">e</span><span class="special">.</span><span class="identifier">what</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
  <span class="special">}</span>

  <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<h5>
<a name="boost_asio.tutorial.tutdaytime6.h1"></a>
        <span class="phrase"><a name="boost_asio.tutorial.tutdaytime6.the_udp_server_class"></a></span><a class="link" href="tutdaytime6.html#boost_asio.tutorial.tutdaytime6.the_udp_server_class">The udp_server
        class</a>
      </h5>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">udp_server</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
</pre>
<p>
        The constructor initialises a socket to listen on UDP port 13.
      </p>
<pre class="programlisting">  <span class="identifier">udp_server</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">io_service</span><span class="special">&amp;</span> <span class="identifier">io_service</span><span class="special">)</span>
    <span class="special">:</span> <span class="identifier">socket_</span><span class="special">(</span><span class="identifier">io_service</span><span class="special">,</span> <span class="identifier">udp</span><span class="special">::</span><span class="identifier">endpoint</span><span class="special">(</span><span class="identifier">udp</span><span class="special">::</span><span class="identifier">v4</span><span class="special">(),</span> <span class="number">13</span><span class="special">))</span>
  <span class="special">{</span>
    <span class="identifier">start_receive</span><span class="special">();</span>
  <span class="special">}</span>

<span class="keyword">private</span><span class="special">:</span>
  <span class="keyword">void</span> <span class="identifier">start_receive</span><span class="special">()</span>
  <span class="special">{</span>
</pre>
<p>
        The function <a class="link" href="../reference/basic_datagram_socket/async_receive_from.html" title="basic_datagram_socket::async_receive_from">ip::udp::socket::async_receive_from()</a>
        will cause the application to listen in the background for a new request.
        When such a request is received, the <a class="link" href="../reference/io_service.html" title="io_service">io_service</a>
        object will invoke the <code class="computeroutput"><span class="identifier">handle_receive</span><span class="special">()</span></code> function with two arguments: a value of
        type boost::system::error_code indicating whether the operation succeeded
        or failed, and a <code class="computeroutput"><span class="identifier">size_t</span></code> value
        <code class="computeroutput"><span class="identifier">bytes_transferred</span></code> specifying
        the number of bytes received.
      </p>
<pre class="programlisting">    <span class="identifier">socket_</span><span class="special">.</span><span class="identifier">async_receive_from</span><span class="special">(</span>
        <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">recv_buffer_</span><span class="special">),</span> <span class="identifier">remote_endpoint_</span><span class="special">,</span>
        <span class="identifier">boost</span><span class="special">::</span><span class="identifier">bind</span><span class="special">(&amp;</span><span class="identifier">udp_server</span><span class="special">::</span><span class="identifier">handle_receive</span><span class="special">,</span> <span class="keyword">this</span><span class="special">,</span>
          <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">placeholders</span><span class="special">::</span><span class="identifier">error</span><span class="special">,</span>
          <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">placeholders</span><span class="special">::</span><span class="identifier">bytes_transferred</span><span class="special">));</span>
  <span class="special">}</span>
</pre>
<p>
        The function <code class="computeroutput"><span class="identifier">handle_receive</span><span class="special">()</span></code> will service the client request.
      </p>
<pre class="programlisting">  <span class="keyword">void</span> <span class="identifier">handle_receive</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&amp;</span> <span class="identifier">error</span><span class="special">,</span>
      <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="comment">/*bytes_transferred*/</span><span class="special">)</span>
  <span class="special">{</span>
</pre>
<p>
        The <code class="computeroutput"><span class="identifier">error</span></code> parameter contains
        the result of the asynchronous operation. Since we only provide the 1-byte
        <code class="computeroutput"><span class="identifier">recv_buffer_</span></code> to contain the
        client's request, the <a class="link" href="../reference/io_service.html" title="io_service">io_service</a>
        object would return an error if the client sent anything larger. We can ignore
        such an error if it comes up.
      </p>
<pre class="programlisting">    <span class="keyword">if</span> <span class="special">(!</span><span class="identifier">error</span> <span class="special">||</span> <span class="identifier">error</span> <span class="special">==</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">error</span><span class="special">::</span><span class="identifier">message_size</span><span class="special">)</span>
    <span class="special">{</span>
</pre>
<p>
        Determine what we are going to send.
      </p>
<pre class="programlisting">      <span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_ptr</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&gt;</span> <span class="identifier">message</span><span class="special">(</span>
          <span class="keyword">new</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">(</span><span class="identifier">make_daytime_string</span><span class="special">()));</span>
</pre>
<p>
        We now call <a class="link" href="../reference/basic_datagram_socket/async_send_to.html" title="basic_datagram_socket::async_send_to">ip::udp::socket::async_send_to()</a>
        to serve the data to the client.
      </p>
<pre class="programlisting">      <span class="identifier">socket_</span><span class="special">.</span><span class="identifier">async_send_to</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(*</span><span class="identifier">message</span><span class="special">),</span> <span class="identifier">remote_endpoint_</span><span class="special">,</span>
          <span class="identifier">boost</span><span class="special">::</span><span class="identifier">bind</span><span class="special">(&amp;</span><span class="identifier">udp_server</span><span class="special">::</span><span class="identifier">handle_send</span><span class="special">,</span> <span class="keyword">this</span><span class="special">,</span> <span class="identifier">message</span><span class="special">,</span>
            <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">placeholders</span><span class="special">::</span><span class="identifier">error</span><span class="special">,</span>
            <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">placeholders</span><span class="special">::</span><span class="identifier">bytes_transferred</span><span class="special">));</span>
</pre>
<p>
        When initiating the asynchronous operation, and if using boost::bind(), you
        must specify only the arguments that match the handler's parameter list.
        In this program, both of the argument placeholders (boost::asio::placeholders::error
        and boost::asio::placeholders::bytes_transferred) could potentially have
        been removed.
      </p>
<p>
        Start listening for the next client request.
      </p>
<pre class="programlisting">      <span class="identifier">start_receive</span><span class="special">();</span>
</pre>
<p>
        Any further actions for this client request are now the responsibility of
        <code class="computeroutput"><span class="identifier">handle_send</span><span class="special">()</span></code>.
      </p>
<pre class="programlisting">    <span class="special">}</span>
  <span class="special">}</span>
</pre>
<p>
        The function <code class="computeroutput"><span class="identifier">handle_send</span><span class="special">()</span></code> is invoked after the service request has
        been completed.
      </p>
<pre class="programlisting">  <span class="keyword">void</span> <span class="identifier">handle_send</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_ptr</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&gt;</span> <span class="comment">/*message*/</span><span class="special">,</span>
      <span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&amp;</span> <span class="comment">/*error*/</span><span class="special">,</span>
      <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="comment">/*bytes_transferred*/</span><span class="special">)</span>
  <span class="special">{</span>
  <span class="special">}</span>

  <span class="identifier">udp</span><span class="special">::</span><span class="identifier">socket</span> <span class="identifier">socket_</span><span class="special">;</span>
  <span class="identifier">udp</span><span class="special">::</span><span class="identifier">endpoint</span> <span class="identifier">remote_endpoint_</span><span class="special">;</span>
  <span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special">&lt;</span><span class="keyword">char</span><span class="special">,</span> <span class="number">1</span><span class="special">&gt;</span> <span class="identifier">recv_buffer_</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<p>
        See the <a class="link" href="tutdaytime6/src.html" title="Source listing for Daytime.6">full source listing</a>
      </p>
<p>
        Return to the <a class="link" href="../tutorial.html" title="Tutorial">tutorial index</a>
      </p>
<p>
        Previous: <a class="link" href="tutdaytime5.html" title="Daytime.5 - A synchronous UDP daytime server">Daytime.5 - A synchronous
        UDP daytime server</a>
      </p>
<p>
        Next: <a class="link" href="tutdaytime7.html" title="Daytime.7 - A combined TCP/UDP asynchronous server">Daytime.7 - A combined
        TCP/UDP asynchronous server</a>
      </p>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright &#169; 2003-2013 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>)
      </p>
</div></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="tutdaytime5/src.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../tutorial.html"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../boost_asio.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="tutdaytime6/src.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a>
</div>
</body>
</html>