Whether deploying to a web container or full JEE server, the following applies:
The server's JVM must be at least version 1.5. Version 1.6 is recommended.[5]
On client machines, the required Java plugin version is 1.6_11 or greater.
Although Mr. XML Publisher's server-side class files can be compiled for running on a version 1.5 JVM, the applets require that client browsers have installed a Java plugin at version 1.6.0_11 or later. The applets' Java plugin version requirement is partly due to the relatively weak support for some SAXParser features in earlier Java plugin versions, but mostly due to the changes Sun made to the Java plugin starting with version 1.6.0_10.
[5] For server's using a version 1.5 JVM, you must make arrangements prior to installation so that Mr. XML Publisher's server-side class files can be compiled specifically for a version 1.5 JVM.