Tuesday, October 16, 2012

Terracotta and Tomcat Clustering - Page 2

Now, download apache-tomcat-6.0.35 and extract it twice to two directories of your choice, i will refer to them as ${CATALINA_HOME_NODE1} and ${CATALINA_HOME_NODE2}.

Copy Terracotta Libraries

we need two jar files to be copied to both Tomcats lib directory.

Copy Terracotta Config File

we need to copy the same Terracotta configuration file to the conf directory of both Tomcats

one small change to do, the client log location, both clients (Tomcat servers) can't be configured with the same client log location.

edit ${CATALINA_HOME_NODE2}\conf\tc-config.xml
change log location under the clients tag
to be

Terracotta Valve

Tomcat connects to Terracotta by intercepting requests via a value, now let's hook that valve.
under the conf directory of both Tomcats, edit the file context.xml to look like this:

 <!-- Default set of monitored resources -->

 <!-- Uncomment this to disable session persistence across Tomcat restarts -->
    <Manager pathname="" />
 <!-- Hook the Terracotta Valve and configure it using the tc-config.xml file -->
 <Valve className="org.terracotta.session.TerracottaTomcat60xSessionValve" tcConfigUrl="../conf/tc-config.xml"/>


note that we have disabled session persistence across Tomcat restarts because that is a task for Terracotta now.

Tomcat HA Configurations


we need to define a unique jvmRoute for each Tomcat server.

edit ${CATALINA_HOME_NODE1}\conf\server.xml, change the Engine tag to look like this:
<Engine name="Catalina" defaultHost="localhost" jvmRoute="tomcat1">

edit ${CATALINA_HOME_NODE2}\conf\server.xml, change the Engine tag to look like this:
<Engine name="Catalina" defaultHost="localhost" jvmRoute="tomcat2">

Make sure you don't have port conflicts

as i am running both Tomcats on the same box, i had to change the ports for the second Tomcat.
in ${CATALINA_HOME_NODE2}\conf\server.xml, i have changed
shutdown port: 8005 to 8006
http port: 8080 to 8081
ajp port: 8009 to 8010

Run both Tomcats

open two more terminals and navigate to ${CATALINA_HOME_NODE1}\bin on one and ${CATALINA_HOME_NODE2}\bin on the other, on both terminals execute:

if everything went as it should, you should see something like that on both Tomcat terminals
Terracotta 3.7.0, as of 20120717-133013 (Revision unknown-20453 by cruise@rh5vmo113.terracotta.lan from 3.7.0)
Successfully loaded base configuration from file at 'H:\terracotta\apache-tomcat-6.0.35\bin\.\..\conf\tc-config.xml'.
Successfully loaded base configuration from file at 'H:\terracotta\apache-tomcat-6.0.35\temp\tc-config8509448930662041153.xml'.
Log file: 'C:\terracotta\client-logs\terracotta-client.log'.
Connection successfully established to server at

Test it

Tomcat comes by default with a web application called examples, we will use it till the end of this tutorial to test our setup

point your browser to http://localhost:8080/examples/ and http://localhost:8081/examples/ and make sure both servers are responding.

open your Terracotta Development Console and make sure that both clients (the tomcat server) are present as below.

also note that the sessions button is now active.