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Copyright 1999-2004 The Apache Software Foundation
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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<author email="hgomez@apache.org">Henri Gomez</author>
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<date>$Date: 2006-06-29 01:56:49 +0200 (Thu, 29 Jun 2006) $</date>
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<section name="General">
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General Informations and FAQ about JK
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<subsection name="Where can I get help/support for JK ?">
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The primary mechanism for support is through the JK
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documentation included in the doc directory.
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Documentation is also available on the Apache Tomcat web site devoted to the
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<a href="http://tomcat.apache.org/connectors-doc/">
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Apache Tomcat Connectors Project</a>
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For additional help, the best resource is the Tomcat Users Discussion list.
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You should start by searching
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<a href="http://mail-archives.apache.org/mod_mbox/tomcat-users/">
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the mail list archive</a>
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before you post questions to the list.
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If you are unable to locate the answer to your question in the archive,
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you can post questions about JK to the user list for assistance.
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Make sure that you include the version of your Webserver,
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that you are using as well as the platform you are running on
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<a href="http://tomcat.apache.org/lists.html">
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to determine how to subscribe to tomcat mailing list.
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<subsection name="I can't find JK anywhere. Where is it?">
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Now that JK moved to the <b>tomcat-connectors</b> repository,
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the source and the binaries for JK can be downloaded from a mirror at the
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<a href="http://tomcat.apache.org/download-connectors.cgi">
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Tomcat Connectors (mod_jk, mod_jk2) Downloads</a> page.
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<subsection name="What's the difference between JK and mod_jk ?">
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<b>JK</b> is a project covering web-servers to Tomcat connectors,
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whereas <b>mod_jk</b> is the <a href="howto/apache.html">Apache module</a> developed in JK.
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<a href="howto/domino.html">Domino webserver</a> support is implemented on JK, using a redirector
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called <b>dsapi redirector</b>.
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<a href="howto/iis.html">IIS webserver</a>support is implemented on JK, using a redirector
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called <b>isapi redirector</b>.
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<a href="howto/nes.html">Netscape/iPlanet webserver</a>webserver support is implemented on JK, using a redirector
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called <b>nsapi redirector</b>.
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<subsection name="Where can I get more information ?">
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For <b>JK 1.2.x</b>, you should read :
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<a href="howto/quick.html">For the impatients</a>
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<a href="howto/apache.html">Apache and JK</a>
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<a href="howto/domino.html">Domino and JK</a>
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<a href="howto/iis.html">IIS and JK</a>
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<a href="howto/nes.html">Netscape/iPlanet and JK</a>
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<a href="howto/workers.html">Workers configuration</a>
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You could also try searching the mailing list archives for "JK" or look at the source.
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<subsection name="Which protocol should I use? Ajp12 or Ajp13?">
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<a href="common/ajpv13a.html">Ajp13</a> is a newer protocol, it's faster, and it works better with SSL.
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You almost certainly want to use it now that <strong>ajp12 is deprecated</strong>.
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Also ajp13 is supported by all Apache Tomcat including 3.2.x , 3.3.x, 4.0.x, 4.1.x and the new tomcat 5.
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Others Servlet engines like <b>jetty</b> have support for Ajp13.
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<subsection name="I've got a firewall between my WebServer and Tomcat who drop ajp13 connections after some times">
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Ajp13 use persistant connections where the traffic could be null if there is no request to be sent to Tomcat.
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Firewall used to drop inactive connections and will make your WebServer and Tomcat think the connection is valid.
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Starting with JK 1.2.0, a <b>socket_keepalive</b> property as been added to ajp13 settings, and you should take a look at
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it in <a href="howto/workers.html">Workers HowTo</a>.
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<subsection name="Under heavy load, I've got many threads in Tomcat even if my Apache Web Server handle much of the load">
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Under heavy load, Apache WebServer create many childs to handle the load, which will in turn create many connections
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to Tomcat to forward the requests they should handle.
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Apache WebServer will normally kill the childs/threads when the load decrease. But if the load is still there and
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even if only Apache handle the requests, ie static contents, the childs are kept and with them the ajp13 connections,
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even if they are no more used.
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Since JK 1.2.0, <b>cache_timeout</b> and <b>recycle_timeout</b> properties as been added to close
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connections after some time of inactivity, for more informations refer to <a href="howto/workers.html">Workers HowTo</a>.
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<section name="Apache">
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Informations and FAQ about mod_jk and Apache Web Servers.
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<subsection name="Whenever I restart Tomcat, Apache locks up!">
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The Ajp13 protocol keeps an open socket between Tomcat and Apache. Release of mod_jk present in J-T-C handle the network failure.
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But with previous release of mod_jk, you may have to restart Apache as well.
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<subsection name="Why did exist two files mod_jk.so (-eapi ad -noeapi) in download dir for Linux ?">
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Many versions of Apache use of modified API, known at Extended API, developed for use with the
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<a href="http://www.modssl.org">mod_ssl module</a>.
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For example, Apache present in certains recent Linux distributions include the
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<b>mod_ssl</b> module.
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So if you got such 'Extended Apache', you need to use <b>mod_jk.so-eapi</b>.
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You should use <b>mod_jk.so-noeapi</b> only for 'Standard Apache' (ie without mod_ssl).
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It's wise to avoid using EAPI modules on STD API Apache or to use standard API modules on EAPI Apache.
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Allways be sure to have the <b>mod_jk.so</b> witch match your version of Apache
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<subsection name="What's that message about 'garbled DSO ?'">
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It's related to Apache EAPI, the message <code>'mod_jk.so is garbled - perhaps this is not an Apache module DSO ?'</code>
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just told you, that your're trying to install a mod_jk.so DSO module that was compiled on an Apache using EAPI,
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like apache-mod_ssl or apache from Redhat distro 6.2/7.0 but your system use the standard apache with normal API.
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<subsection name="And the message about 'module might crash under EAPI!">
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Also related to EAPI, the message <code>'[warn] Loaded DSO /usr/lib/apache/mod_jk.so uses plain Apache 1.3 API,
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this module might crash under EAPI! (please recompile it with -DEAPI)'</code>, the mod_jk.so was compiled under normal
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Apache with standard API and you try to install the module on an Apache using EAPI.
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<subsection name="APXS is getting an error during the build of mod_jk, like rc=0 or rc=255. I tried all of the steps in the build section, what do I do now ?">
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APXS is a Perl script that is created when you build the Apache web server from source.
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Chances are that if you are getting these errors and you obtained Apache as a binary distribution,
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that APXS is not configured correctly for your system.
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Your best bet is to get the Apache source from http://httpd.apache.org and build it yourself.
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Use the following for a basic build (read the Apache docs for other options):
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<type>cd /usr/local/src</type><br/>
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<type>gzip -dc apache_1.3.19.tar.gz|tar xvf -</type><br/>
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<type>cd apache_1.3.19</type><br/>
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<type>./configure --prefix=/usr/local/apache \</type><br/>
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<type> --enable-module=most \</type><br/>
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<type> --enable-shared=max</type><br/>
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<type>make</type><br/>
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<type>make install</type><br/>
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Note: The above steps assume that you downloaded the Apache source and placed it in your /usr/local/src directory.
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<subsection name="Apache 2.0 complains about incorrect module version">
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Since Apache 2.0 API still change often, the Apache 2.0 teams decide to put in headers of compiled modules the
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Apache 2.0 version used to compile the module. This check is called Magic Module Number bump.
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At start time Apache 2.0 check that version in modules headers and stop if it detect that a module was compiled
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for another Apache 2.0 version. As such you should allways use modules compiled for the same Apache 2.0 version.
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This check may be removed if the future.
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<subsection name="JNI didn't works with Apache 1.3">
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JNI support require a multi-threaded environment which is not the general case for Apache 1.3.
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You should verify if Apache 1.3 has been build with thread support and if not you could add the
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the pthreads library to your <b>httpd.conf</b> file.
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# Add pthread to Apache in httpd.conf
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LoadModule "/usr/lib/libpthreads.so"
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Also keep in mind that JNI is suited for multi-threaded servers and you should consider upgrading
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to Apache 2.0 to support JNI.
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<subsection name="JNI report that JVM couldn't be started under Linux">
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Under Linux, you should set some environment variables BEFORE launching your Apache server :
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<read>export LD_LIBRARY_PATH=$jre/bin:$jre/bin/classic:$LD_LIBRARY_PATH</read>
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Also some Linux distributions have enabled a GLIBC feature called 'floating stacks' which may not works with kernel
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less than 2.4.10 on SMP machines. You should disable floating stacks by exporting an environment variable :
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<read>export LD_ASSUME_KERNEL=2.2.5</read>
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You could have to update your service scripts, ie <b>/etc/rc.d/init.d/httpd</b>, to set these env vars
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before your httpd server starts.
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<subsection name="Mixed errors when building via configure">
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configure assume you have some GNU tools allready installed and configured for your system, and ad minima <b>libtool</b>.
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Also some systems may have mixed cc and gcc setup which may make you puzzled when trying to link an Apache built with native
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c compiler with a jk/jk2 build with gcc.
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In fine some native make didn't works as expect so you should use a GNU make <b>gmake</b>.
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<subsection name="JK2 build report error about missing FIONBIO on Solaris 8">
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In JK2 before v2.0.2, you should add <source>#define BSD_COMP</source> in top
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of jk/native2/common/jk_channel_socket.c to have Solaris build succeed.
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Informations and FAQ about JK and IIS Web Servers.
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More informations to be added.
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<section name="NES/iPlanet">
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Informations and FAQ about JK and NES/iPlanet Web Servers.
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More informations to be added.
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