Jetty Session Clustering with Terracotta

Terracotta is an infrastructure that allows you to pretty much transparently cluster any code in a jvm. We’ve already successfully used it to cluster the channels in Jetty’s Bayeux (aka Cometd) implementation, so we thought it was high time we used it to cluster HTTP sessions.

Jetty already has a WADI-based solution for HTTP session clustering, so providing a terracotta-based solution provides an alternative for users to be able to choose the most appropriate solution for their needs.

The code is hot-off-the-press, so thus requires a little more polishing and testing, however it’s ready to try out, so give it a spin. Here’s the instructions:

Building

1. There are some changes to Jetty that have not yet been incorporated into trunk, so first you’ll need to check out this branch:

   https://svn.codehaus.org/jetty/jetty/branches/terracotta.
   

   Build it with:

   mvn clean install
   

   I’ll refer to the location where you’ve done the checkout as $JETTY-BRANCH.

2. Check out the session clustering code from the jetty-contrib repo at:

   https://svn.codehaus.org/jetty-contrib/jetty/trunk/extras/terracotta. 

   Build it with:

   mvn clean install
   I'll refer to the location where you've done the checkout as $TC_EXTRAS.
   



3. Copy the terracotta-sessions-6.1-SNAPSHOT.jar you just built into $JETTY-BRANCH/lib/ext.


4. Check out terracotta trunk from:

   http://svn.terracotta.org/svn/tc/dso/trunk
   

   Follow the instructions on the terracotta site to build it and produce a bootjar. I'll refer to the root of the build results (usually in code/base/build/) as $TC-BUILD.

Configuration

1. You can setup all your webapps to use terracotta-based session clustering by copying the example jetty config file in $TC-EXTRAS/src/main/resources/jetty.xml to your $JETTY-BRANCH/etc/ directory.
2. You might want to copy the example webapps from $TC-BUILD/dist/terracotta-trunk/samples/sessions into $JETTY-BRANCH/webapps to play with.

Running

Start the terracotta server:

$TC-BUILD/dist/terracotta-trunk/bin/start-tc-server.sh
-f $TC-EXTRAS/src/main/resources/tc-config-jetty.xml

Start jetty:

cd $JETTY-BRANCH
java -Dtc.install-root=$TC_BUILD/dist/terracotta-trunk/
-Xbootclasspath/p:[path to your boot jar]
-Dtc.config=$TC-EXTRAS/src/main/resources/tc-config-jetty.xml
-jar start.jar
etc/jetty.xml

Job done!

Any webapps you deployed should have their session instances clustered. Don't forget, you'll need to start more than one jetty instance in order to see session clustering actually happening 🙂

Many thanks are due to the guys at Terracotta for their expert help in the integration, in particular Tim Eck who was outstandingly helpful - thanks Tim!

Java One

If you're attending Java One, we'll be hanging out and demo-ing the session clustering at the Terracotta booth (booth #828) so drop by, eyeball the demo and come and have a chat to us.