By James Ward and Matt Raible.
Happy Trails is a web application that was written in Play 2 (Java) and Grails 2 in order to do a side-by-side comparison of the two frameworks. The results of this comparison were initially presented at UberConf on June 21, 2012. If you'd like to read more about this session and its conclusions, see Play vs. Grails Smackdown at ÜberConf.
The applications were updated for Play 2.1.0 and Grails 2.2.1 and findings were presented at Devoxx France on March 28, 2013. To read more about this session, see this blog post.
Happy Trails is released under version 2.0 of the Apache License.