Cluster Load Balance

step 1:

     download jdkx.x, tomcat 6.0 ,  apache http server [latest], jmeter [optional]

step2 :
       install jdk

    install  2 or 3 or n copies of tomcat 6.0 as tomcatA, tomcatB, tomcatC

step3:
     open server.xml in tomcatx.x\conf

change tomcatA

port="8115" shutdown="SHUTDOWN">

port="8111" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />

port="8119" protocol="AJP/1.3" redirectPort="8443" />

jvmRoute="tomcatA">


   



change tomcatB

port="8225" shutdown="SHUTDOWN">

port="8221" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />

port="8229" protocol="AJP/1.3" redirectPort="8443" />

jvmRoute="tomcatA">

   

change tomcatC [ports]


step 4

Add distributed tag in web.xml

Next step to do add distributed tag in web.xml to switching session among the tomcat clustering instance
Make any application, e.g we are making cluster as application folder in webapps
1. TomcatA - >  webapps - > cluster -> WEB-INF -> web.xml
2. TomcatB - >  webapps - > cluster -> WEB-INF -> web.xml
3. TomcatC - >  webapps - > cluster -> WEB-INF -> web.xml
Add  in all three web.xml file

"http://java.sun.com/xml/ns/javaee"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
   version="2.5">
 
 

step 5

Install mod_jk in module

Mod_jk is connector that communicates with apache web server and tomcat. We need to download and copy that connector in module folder of apache
http://tomcat.apache.org/connectors-doc/ we are using latest connector of mod_jk
Make mod_jk.log file in logs folder otherwise apache will throw error
RENAME MOD_JK.SO OR MOD_JK.[WINDOWS]


server.xml

Include c:/apache-tomcat/conf/auto/mod_jk.conf
[httpd.conf]


step 6

Edit in httpd.conf

Open apache -> httpd.conf
Open in any text editor and add

LoadModule jk_module modules/mod_jk-apache-2.2.4.so
JkWorkersFile "C:\cluster\Apache\conf\workers.properties"
JkLogFile "logs/mod_jk.log"
JkLogLevel error
JkMount /cluster loadbalancer
JkMount /cluster/* loadbalancer

Worker.properties file

Make a file with name of workers.properties in conf folder. This file tells properties of all tomcat instances. We have to specify all tomcat properties here. Apache will forword request to tomcat through this file
Vertical tomcat clustering this file like

workers.tomcat_home=/tomcatA
workers.java_home=$JAVA_HOME
ps=/
worker.list=tomcatA,tomcatB,tomcatC,loadbalancer

worker.tomcatA.port=8119
worker.tomcatA.host=localhost
worker.tomcatA.type=ajp13
worker.tomcatA.lbfactor=1

worker.tomcatB.port=8229
worker.tomcatB.host=localhost
worker.tomcatB.type=ajp13
worker.tomcatB.lbfactor=1
worker.tomcatC.port=8339
worker.tomcatC.host=localhost
worker.tomcatC.type=ajp13
worker.tomcatC.lbfactor=1
worker.loadbalancer.type=lb
worker.loadbalancer.balanced_workers=tomcatA,tomcatB,tomcatC
worker.loadbalancer.sticky_session=1

step 7



worker.tomcatC.lbfactor=100
increase and decrease request to this tomcatC instance

Restart apache, tomcatA, tomcatB, tomcatC

Check clustering if apache start properly, It is fine without any errors otherwise check problems,basically mod_jk problems come. So download different mod_jk for your machine. Start all tomcats, tomcatA, tomcatB, and tomcatC. If all tomcats is started this means tomcat is working fine.
Open test.jsp on browser and check session id. Check which tomcat on test.jsp is running tomcatB or tomcatC. Close that tomcat, reload test.jsp. Check session id,if session id is same. Then tomcat clustering is working fine.

Test jsp file

Make test.jsp in cluster folder of webapps
tomcatA

<%
  session.setAttribute("a","a");
%>







 
   
   
 
 
   
   
 

TomcatA Machine
Session ID :	<%=session.getId()%>

tomcatB

<%
  session.setAttribute("a","a");
%>







 
   
   
 
 
   
   
 

TomcatB Machine
Session ID :	<%=session.getId()%>

TomcatC
<%
  session.setAttribute("a","a");
%>







 
   
   
 
 
   
   
 

TomcatC Machine
Session ID :	<%=session.getId()%>

step 8


[httpd.conf]
Alias /docs /var/www/html/docs

JkMount /docs loadbalancer
JkMount /docs/* loadbalancer

JkUnMount /docs/*.gif loadbalancer
JkUnMount /docs*.png  loadbalancer


or

If the Tomcat Host appBase (webapps) directory is accessible by the Apache web server, Apache can be configured to serve web application context directory static files instead of passing the request to Tomcat.
Caution: For security reasons is is strongly recommended that JkMount is used to pass all requests to Tomcat by default and JkUnMount is used to explicitly exclude static content to be served by httpd. It should also be noted that content served by httpd will bypass any security constraints defined in the application's web.xml.
Use Apache's Alias directive to map a single web application context directory into Apache's document space for a VirtualHost:

# Static files in the examples webapp are served by apache
  Alias /examples /vat/tomcat3/webapps/examples
  # All requests go to worker1 by default
  JkMount /* worker1
  # Serve html, jpg and gif using httpd
  JkUnMount /*.html worker1
  JkUnMount /*.jpg  worker1



  JkUnMount /*.gif  worker1

links

http://www.easywayserver.com/implementation-tomcat-clustering.htm#server-xml

http://tomcat.apache.org/connectors-doc/webserver_howto/apache.html