Caucho Technology, the people who brought us Resin, now offer a Java-based implementation of PHP that can run on Java application servers.

PHP is a very popular platform for building Web applications. MediaWiki (the wiki software behind Wikipedia) and WordPress (the blogging software behind this blog) are PHP applications, as is the popular bulletin board/forums application, phpBB (obviously).

Now, Caucho Technology, best known for Resin, has developed its own implementation of PHP 5 in Java. Released under the Open Source GPL license, Quercus is 100% Java and comes with a number of PHP modules and extensions included, providing the means to integrate PHP scripts with Java. The web site has a list of PHP applications known to work with Quercus, and has pointers to instructions for installing these applications on top of Quercus in your own Java application server environment.

Since it's provided as a ".war" file, it can be installed on any compliant Java application server (GlassFish, Tomcat), but the instructions focus on Resin as the target environment. Still, this looks like a really useful package that allows Java application server environments to run applications like MediaWiki and WordPress, and to enable PHP scripts to work with Java technologies like JMS or Grails.