Using FreeMarker with Apache Sling

Question

I'm using a Content Repository (Adobe CQ5) that has Apache Sling underneath. I'd like to render web pages using FreeMarker instead of JSP.

For that to work should I upload the OSGi Freemarker extension to Sling, which is to be found in the contribution part of Sling source code, or should I upload an OSGi version of Freemarker instead? Both jars implement the interface javax.script.ScriptEngineFactory so I don't know which one to use, or to upload both.

Answer 1

I managed to get Freemarker working on CQ5.3 by doing the following:

1. get the source from svn checkout http://svn.apache.org/repos/asf/sling/trunk sling
2. go to the contrib/scripting/freemarker and remove all the logging and slf4j references from FreemarkerScriptEngine.java - it throws a 500 error due to NoClassDefFoundException - I think there is a conflict between CQ5 and a version of slf4j included in Freemarker (I didn't dig to find out what was wrong)
3. build it and install, it should appear in the Sling console under bundles and in the 'script engines' page, and let you use .ftl scripts now.

I did it slightly differently by creating the bundle inside CQ5, importing the code and adding a stock freemarker.jar into the bundle but this should work too as it's basically the same thing.

The problem I had was that the script engine does get listed but the logging prevents it from running, that's why you need to remove the log & slf4j from the engine.

Answer 2

I don't know about the OSGi version of Freemarker; we created our own bundling of Freemarker specially for Sling. If you have success using the OSGi version of Freemarker let us know ;-)

Testing is easy: Just install the bundle through the Web Console and check for the supported Script Engines in the Web Console Configuration Status. If you see the Freemarker Engine listed there, it should work.