If you remember back to my previous post, Intro to Ehcache Server and RESTful Web Services, I went into detail regarding how to set up an out-of-process caching server. If you’re lucky enough to be using ColdFusion 9 and have upgraded to the latest 9.0.1 patch, you may have noticed that one of the updates was to update Ehcache 1.6 to version 2.0. This update enables you to tie your ColdFusion instance in with a Terracotta distributed caching server.

Terracotta.org

Why Distributed Caching?

The standard ColdFusion 9 installation provides some new caching mechanisms which utilize Ehcache. This method of caching happens on the same server as the application and within the same JVM. Unfortunately, whenever you perform any caching at this level, your cache will consume the same resources that are normally allocated to your application server.

The obvious downside is that you’re going to run out of memory easier this way. So instead of scaling up (by adding more ram) you can utilize a distributed caching method in order to scale outward.

Installation and Configuration

These steps have been borrowed from the Ehcache Documentation.

The easiest way to get started is to download the Terracotta/Ehcache server installer. You can get those files from the Terracotta website.

Once installed, go into the ehcache directory from where you installed Terracotta and copy ehcache-terracotta-2.0.0.jar from there and place it into your lib folder where you installed ColdFusion. In my case (multiserver deployment) this folder was found under C:\JRun4\servers\cfusion\cfusion-ear\cfusion-war\WEB-INF\cfusion\lib.

Next edit the ehcache.xml file from that same folder to modify the defaultCache tag to look like the following:

<terracottaConfig url="localhost:9510" />
<defaultCache
	...
	>
	<terracotta clustered="true" />
</defaultCache>

Finally, start the Terracotta server by invoking start-tc-server.bat from your terracotta/bin directory. Make sure you also restart your ColdFusion services to ensure the new configuration is loaded properly.

Download Terracotta 3.2.1 Installer

Testing Your Distributed Cache

Now for the fun part. With Terracotta running and ColdFusion connected to it correctly, we can now start putting some objects into our cache. For my test I added the following code:

<h2>Get "CacheTest" from the cache:</h2>
<cfdump var="#CacheGet('CacheTest')#" /><br />

<h2>Set "CacheTest" to be Now():</h2>
<cfset CachePut('CacheTest', Now()) /><br />

<h2>Get "CacheTest" from the cache:</h2>
<cfdump var="#CacheGet('CacheTest')#" />

And as (hopefully!) expected, our cache is working:

It would be a good idea to run the Terracotta Developer Console. From here you’ll be able to manage and monitor your Terracotta cluster. Simply call dev-console.bat from the terracotta/bin directory to start it up.

You can see that the CacheTest object we added to the cache is visible from this console:

Okay, What Next?

It’s all well and dandy that we have our caching server running, but that’s using a default installation and configuration setup for Terracotta. If we want to make it even more powerful, we’ll need to configure a tc-config.xml file to work with our server. You can find a default one with plenty of annotations under the directory where you installed terracotta at /docs/tc-config-express-reference.xml.

For a lot more information about how to configure it, check out the documentation at Terracotta.org.

You may also be interested in configuring Terracotta to reconnect automatically to prevent short network disruptions (which it doesn’t do by default). Check it out here.

Terracotta.org – tc-config.xml reference

Tags: advanced, Caching, ColdFusion, distributed, Ehcache, Terracotta

This entry was posted on Saturday, July 24th, 2010 at 12:41 pm and is filed under Caching, ColdFusion. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.