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<!DOCTYPE document [
<!ENTITY project SYSTEM "project.xml">
<document url="apr.html">
<title>Apache Portable Runtime (APR) based Native library for Tomcat</title>
<author>Remy Maucherat</author>
<section name="Table of Contents">
<section name="Introduction">
Tomcat can use the <a href="">Apache Portable Runtime</a> to
provide superior scalability, performance, and better integration with native server
technologies. The Apache Portable Runtime is a highly portable library that is at
the heart of Apache HTTP Server 2.x. APR has many uses, including access to advanced IO
functionality (such as sendfile, epoll and OpenSSL), OS level functionality (random number
generation, system status, etc), and native process handling (shared memory, NT
pipes and Unix sockets).
These features allows making Tomcat a general purpose webserver, will enable much better
integration with other native web technologies, and overall make Java much more viable as
a full fledged webserver platform rather than simply a backend focused technology.
<section name="Installation">
APR support requires three main native components to be installed:
<li>APR library</li>
<li>JNI wrappers for APR used by Tomcat (libtcnative)</li>
<li>OpenSSL libraries</li>
<subsection name="Windows">
Windows binaries are provided for tcnative-1, which is a statically compiled .dll which includes
OpenSSL and APR. It can be downloaded from <a href="">here</a>
as 32bit or AMD x86-64 binaries.
In security conscious production environments, it is recommended to use separate shared dlls
for OpenSSL, APR, and libtcnative-1, and update them as needed according to security bulletins.
Windows OpenSSL binaries are linked from the <a href="">Official OpenSSL
website</a> (see related/binaries).
<subsection name="Linux">
Most Linux distributions will ship packages for APR and OpenSSL. The JNI wrapper (libtcnative) will
then have to be compiled. It depends on APR, OpenSSL, and the Java headers.
<li>APR 1.2+ development headers (libapr1-dev package)</li>
<li>OpenSSL 0.9.7+ development headers (libssl-dev package)</li>
<li>JNI headers from Java compatible JDK 1.4+</li>
<li>GNU development environment (gcc, make)</li>
The wrapper library sources are located in the Tomcat binary bundle, in the
<code>bin/tomcat-native.tar.gz</code> archive.
Once the build environment is installed and the source archive is extracted, the wrapper library
can be compiled using (from the folder containing the configure script):
<source>./configure &amp;&amp; make &amp;&amp; make install</source>
<section name="APR Components">
Once the libraries are properly installed and available to Java (if loading fails, the library path
will be displayed), the Tomcat connectors will automatically use APR. Configuration of the connectors
is similar to the regular connectors, but have a few extra attributes which are used to configure
APR components. Note that the defaults should be well tuned for most use cases, and additional
tweaking shouldn't be required.
When APR is enabled, the following features are also enabled in Tomcat:
<li>Secure session ID generation by default on all platforms (platforms other than Linux required
random number generation using a configured entropy)</li>
<li>OS level statistics on memory usage and CPU usage by the Tomcat process are displayed by
the status servlet</li>
<section name="APR Lifecycle Listener Configuration">
<subsection name="AprLifecycleListener">
<attribute name="SSLEngine" required="false">
Name of the SSLEngine to use. off: Do not use SSL, on: Use SSL but no specific ENGINE.
The default value is <b>on</b>.
This initializes the native SSL engine, then enable the use of this engine in the connector
using the <code>SSLEnabled</code> attribute. Example:
<source><![CDATA[<Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />]]></source>
<p>See the <a href="">Official OpenSSL
website</a> for more details on SSL hardware engines and manufacturers.
<section name="APR Connectors Configuration">
<subsection name="HTTP/HTTPS">
<p>For HTTP configuration, see the <a href="config/http.html">HTTP</a>
connector configuration documentation.</p>
<p>For HTTPS configuration, see the
<a href="config/http.html#SSL_Support">HTTPS</a> connector configuration
<p>An example SSL Connector declaration is:</p>
<source><![CDATA[<Connector port="443" maxHttpHeaderSize="8192"
enableLookups="false" disableUploadTimeout="true"
acceptCount="100" scheme="https" secure="true"
SSLCertificateKeyFile="${catalina.base}/conf/localhost.key" />]]></source>
<subsection name="AJP">
<p>For AJP configuration, see the <a href="config/ajp.html">AJP</a>
connector configuration documentation.</p>