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Subject cvs commit: jakarta-tomcat-connectors/jk/xdocs faq.xml
Date Mon, 02 Sep 2002 10:50:23 GMT
hgomez      2002/09/02 03:50:23

  Added:       jk/xdocs faq.xml
  The long awaited FAQ is now on it's own file
  Revision  Changes    Path
  1.1                  jakarta-tomcat-connectors/jk/xdocs/faq.xml
  Index: faq.xml
  <?xml version="1.0"?>
  <author email="">Henri Gomez</author>
  <section name="General">
  General Informations and FAQ about mod_jk
  <subsection name="Where can I get help/support for mod_jk?">
  The primary mechanism for support is through the mod_jk 
  documentation included in the doc directory.
  Documentation is also available on the Apache Jakarta web site devoted to the
  <a href="">
  Jakarta Tomcat Connectors Project</a>
  For additional help, the best resource is the Tomcat Users Discussion list.  
  You should start by searching
  <a href="">
  the mail list archive</a>
  before you post questions to the list.  
  If you are unable to locate the answer to your question in the archive, 
  you can post questions about mod_jk to the user list for assistance.  
  Make sure that you include the version of your Webserver, 
  that you are using as well as the platform you are running on
  and go 
  <a href="">
  to determine how to subscribe to tomcat mailing list.
  <subsection name="I can't find mod_jk anywhere. Where is it?">
  Now that mod_jk moved to the jakarta-tomcat-connectors repository, 
  the source and binaries for mod_jk are present 
  in the <a href="">
  jakarta-tomcat-connectors directory</a>
  <subsection name="Where can I get more information ?">
  For mod_jk 1.2.x the <a href="jk/config-howto.html">
  mod_jk-config howto document</a> has considerably more in-depth information.
  For mod_jk 2.0.x the <a href="jk2/configtc.html">
  config tomcat</a> and <a href="jk2/configweb.html">config webserver</a>
  documents have considerably more in-depth information.
  It's worth a look. 
  You could also try searching the mailing list archives for "mod_jk" or look at the source.
  <subsection name="Which protocol should I use? Ajp12 or Ajp13?">
  <a href="common/AJPv13.html">Ajp13</a> is a newer protocol, it's faster, and
it works better with SSL. You almost certainly want to use it. 
  There is more information in the howto document, ajp12 is now deprecated.

  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. 
  Others Servlet engine like jetty have support for Ajp13.
  <subsection name="I've got a firewall between my WebServer and Tomcat who drop ajp13
connections after some times">
  Ajp13 use persistant connections where the traffic could be null if there is no request
to be sent to Tomcat. 
  Firewall used to drop inactive connections and will make your WebServer and Tomcat think
the connection is valid. 
  Since mod_jk 1.2.0 a socket_keepalive property as been added to ajp13 settings, and you
should take a look at 
  it in howto
  <subsection name="Under heavy load, I've got many threads in Tomcat even if my Apache
Web Server handle much of the load">
  Under heavy load, Apache WebServer create many childs to handle the load, which will in
turn create many connections 
  to Tomcat to forward the requests they should handle. 
  Apache WebServer will normally kill the childs/threads when the load decrease. But if the
load is still there and 
  even if only Apache handle the requests, ie static contents, the childs are kept and with
them the ajp13 connections, 
  even if they are no more used. 
  Since mod_jk 1.2.0 cache_timeout and socket_timeout properties as been added to close connections
after some time, 
  for more informations refer to howto
  <section name="Apache">
  Informations and FAQ about mod_jk and Apache Web Servers. 
  <subsection name="Whenever I restart Tomcat, Apache locks up!">
  The Ajp13 protocol keeps an open socket between Tomcat and Apache. Release of mod_jk present
in J-T-C handle the network failure. 
  But with previous release of mod_jk, you may have to restart Apache as well.
  <subsection name="Why did exist two files (-eapi ad -noeapi) in download dir
for Linux ?">
  Many versions of Apache use of modified API, known at Extended API. For example, Apache
using mod_ssl or 
  Apache present in certains recent Linux distributions. So if you got such 'Extended Apache',

  you need to use, or use for standard Apache. 
  It's wise to avoid using EAPI modules on STD API Apache or to use standard API modules on
EAPI Apache. 
  Allways be sure to have the for your version of Apache
  <subsection name="What's that message about 'garbled DSO ?'">
  It's related to Apache EAPI, the message ' is garbled - perhaps this is not an
Apache module DSO ?' 
  just told you are trying to install a DSO module that was compiled on an Apache
using EAPI, 
  like apache-mod_ssl or apache from Redhat distro 6.2/7.0 but your system use the standard
apache with normal API.
  <subsection name="And the message about 'module might crash under EAPI!">
  Also related to EAPI, the message '[warn] Loaded DSO /usr/lib/apache/ uses plain
Apache 1.3 API, 
  this module might crash under EAPI! (please recompile it with -DEAPI)', the was
compiled under normal 
  Apache with standard API and you try to install the module on an Apache using EAPI.
  <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 ?">
  APXS is a Perl script that is created when you build the Apache web server from source.
  Chances are that if you are getting these errors and you obtained Apache as a binary distribution,

  that APXS is not configured correctly for your system.  
  Your best bet is to get the Apache source from and build it yourself.
  Use the following for a basic build (read the Apache docs for other options):
  <type>cd /usr/local/src</type><br/>
  <type>gzip -dc apache_1.3.19.tar.gz|tar xvf -</type><br/>
  <type>cd apache_1.3.19</type><br/>
  <type>./configure --prefix=/usr/local/apache \</type><br/>
  <type>            --enable-module=most \</type><br/>
  <type>            --enable-shared=max</type><br/>
  <type>make install</type><br/>
  Note: The above steps assume that you downloaded the Apache source and placed it in your
/usr/local/src directory.
  <subsection name="Apache 2.0 complains about incorrect module version">
  Since Apache 2.0 API still change often, the Apache 2.0 teams decide to put in headers of
compiled modules the 
  Apache 2.0 version used to compile the module. 
  At start time Apache 2.0 check that version in modules headers and stop if it detect that
a module was compiled 
  for another Apache 2.0 version. As such you should allways use modules compiled for the
same Apache 2.0 version. 
  This check may be removed if the future.
  <subsection name="JNI didn't works with Apache 1.3">
  JNI support require a multi-threaded environment which is not the general case for Apache
  You should verify if Apache 1.3 has been build with thread support and if not you could
add the 
  LoadModule "/usr/lib/" in your httpd.conf. 
  Also keep in mind that JNI is suited for multi-threaded servers and you should consider
  to Apache 2.0 to support JNI.
  <subsection name="JNI report that JVM couldn't be started under Linux">
  Under Linux, you should set some environment variables BEFORE launching your Apache server
  export LD_LIBRARY_PATH=$jre/bin:$jre/bin/classic:$LD_LIBRARY_PATH
  Also some Linux distributions have enabled a GLIBC feature called 'floating stacks' which
may not works with kernel 
  less than 2.4.10 on SMP machines. You should disable floating stacks by exporting an environment
variable :
  export LD_ASSUME_KERNEL=2.2.5
  You could have to update your service scripts, ie /etc/rc.d/init.d/httpd, to set these env
vars before your httpd server starts.
  <section name="IIS">
  Informations and FAQ about mod_jk and IIS Web Servers. 
  More informations to be added, Nacho ?
  <section name="NES/iPlanet">
  Informations and FAQ about mod_jk and NES/iPlanet Web Servers. 
  More informations to be added, Mike ?

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