title: Cannot load modules/mod_proxy_wstunnel.so into server
body: <p>Recently I need integrate a websocket server with apache2，and I find that apache2.4 has supported websocket with the module : <code>mod_proxy_wstunnel</code>.
  <a href="http://httpd.apache.org/docs/2.4/mod/mod_proxy_wstunnel.html" rel="nofollow noreferrer">http://httpd.apache.org/docs/2.4/mod/mod_proxy_wstunnel.html</a></p>
  
  <p>I compiled them by myself, but encountered a problem : </p>
  
  <p><code>httpd: Syntax error on line 122 of /usr/local/apache2/conf/httpd.conf: Cannot load modules/mod_proxy_wstunnel.so into server: /usr/local/apache2/modules/mod_proxy_wstunnel.so: undefined symbol: ap_proxy_release_connection</code></p>
  
  <ul>
  <li>environment info: </li>
  <li>OS:centos 6.8 </li>
  <li>php:php-7.0.10 </li>
  <li>apache:httpd-2.4.23</li>
  </ul>
  
  <p>My steps are:</p>
  
  <ol>
  <li>Download source code.
  
  <ul>
  <li>php7  github.com/php/php-src/releases/tag/php-7.0.10  </li>
  <li>apache2.4 github.com/apache/httpd/releases/tag/2.4.23<br></li>
  </ul></li>
  <li>Copy to my workspace and tar，say /home
  
  <ul>
  <li>shell> tar -xjf php-7.0.10.tar.bz2</li>
  <li>shell> tar -xjf httpd-2.4.23.tar.bz2</li>
  </ul></li>
  <li>Install gcc : yum install gcc</li>
  <li>Compile apache
  
  <ul>
  <li>down apr：<code>apr-1.5.2.tar.gz</code>    <code>apr-util-1.5.4.tar.gz</code></li>
  <li>copy to <code>/httpd-2.4.23/srclib</code><br>
  <code>tar -zvf apr-1.5.2.tar.gz</code>     <code>tar -zvf apr-util-1.5.4.tar.gz</code></li>
  <li>Modify the files name: <br><code>apr-1.5.2</code> as <code>apr</code>   <br>    <code>apr-util-1.5.4</code> as <code>apr-util</code><br></li>
  <li>Install pcre<br>
  <code>yum install pcre-devel</code><br></li>
  <li><code>./configure --enable-so --enable-http --enable-proxy --enable-proxy-http --with-included-apr --enable-proxy-wstunnel</code></li>
  <li>make &amp;&amp; make install</li>
  <li>set apache server ip：<br>
  shell> <code>vi /usr/local/apache2/conf/httpd.conf</code>
  ServerName 127.0.0.1</li>
  </ul></li>
  <li>Compile php
  
  <ul>
  <li>libxml2:<br>yum install libxml2-devel</li>
  <li>mkdir /usr/local/php7</li>
  <li>./configure --prefix=/usr/local/php7 --with-mysqli --enable-mysqlnd --with-mysql-sock=/var/lib/mysql/mysql.sock --with-apxs2=/usr/local/apache2/bin/apxs</li>
  <li>make &amp;&amp; make install</li>
  <li>cp -v ./php.ini-production /usr/local/php7/lib/php.ini</li>
  <li>configure httpd.conf<br>
  shell> vi /usr/local/apache2/conf/httpd.conf<br>
  <code>&lt;FilesMatch \.php$&gt;
  SetHandler application/x-httpd-php
  &lt;/FilesMatch&gt;</code></li>
  </ul></li>
  <li>enalbe mod_proxy_wstunnel
  shell> vi /usr/local/apache2/conf/httpd.conf<br>
  <code>LoadModule proxy_wstunnel_module modules/mod_proxy_wstunnel.so</code></li>
  </ol>
  
  <p>Above is my steps. Then I try to start my apache2 : </p>
  
  <p><code>/usr/local/apache2/bin/apachectl start</code></p>
  
  <p>Got the following errors:</p>
  
  <p><code>httpd: Syntax error on line 122 of /usr/local/apache2/conf/httpd.conf: Cannot load modules/mod_proxy_wstunnel.so into server: /usr/local/apache2/modules/mod_proxy_wstunnel.so: undefined symbol: ap_proxy_release_connection</code></p>
  
  <p>I have google it , but can't find some helpful info.</p>