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Load Balancing and Clustering Tomcat

There are two ways of Clustering applications on Tomcat
1. Sticky Session
User request will always goes to same tomcat instance
2. Session Replication
User request can go to any tomcat in cluster and his session is copied on entire cluster

There are pros and cons of both approach, however i'll update this blog later on those.

Lets get started for Sticky Session based clustering and load balancing.

Use-Case
Setting up two tomcat along with apache on same windows machine.

Pre-requirements
1. install Apche 2.x
2. download tomcat 5.x /6.x and make an extra copy

Steps 1. open httpd.conf from apache_home/conf/ and add these lines at the end

BalancerMember ajp://localhost:8009/ route=tomcatA
BalancerMember ajp://localhost:8010/ route=tomcatB

ProxyPass balancer://mycluster/ stickysession=JSESSIONID

SetHandler balancer-manager
Order Deny,Allow
Deny from all
Allow from localhost

Step 2.

uncomment the following four lines

LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_ajp_module modules/mod_proxy_ajp.so
LoadModule proxy_balancer_module modules/mod_proxy_balancer.so
LoadModule status_module modules/mod_status.so

Step 3.

open tomcat_home_1/conf/server.xml and add jvmRoute="tomcatA" to the following line

Engine name="Catalina" defaultHost="localhost"

so it should look like this
Engine name="Catalina" defaultHost="localhost" jvmRoute="tomcatA"
Step 4.

open tomcat_home_2/conf/server.xml and add jvmRoute="tomcatB" to the following line

Engine name="Catalina" defaultHost="localhost"

so it should look like this
Engine name="Catalina" defaultHost="localhost" jvmRoute="tomcatB

also change the following port nos


Server port="8006" shutdown="SHUTDOWN"

Connector port="8081" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="8444"

Connector port="8010" protocol="AJP/1.3" redirectPort="8444"

Thats It!

start apache, tomcatA, tomcatB and

navigate to http://localhost/
also checkout balancer-manager
http://localhost/balancer-manager

for more configuration and understanding checkout the following link




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