Mule 2.1

Mule 2.1 is developed and tested against JDK 5. Having said that, Mule 2.x will generally run without issues in JDK 6 also since the JRE itself is backwards-compatible. As of Mule 2.1 we have taken the plunge and will no longer support JDK 1.4

Mule 2.0

Mule 2.0 is developed and tested against JDK 5. Mule 2.0 will not run on JDK 1.4 out of the box but you're still able to compile the source yourself with JDK 1.4 with the exception of a few newer modules. Have a look at [the build instructions ] for details.

Mule 1.x

Mule 1.x is developed and tested against JDK 1.4.2. In the few cases where a 3rd party library makes use of JDK 5 functionality, that library is retrotranslated to be runnable in JDK 1.4.2 Having said that, Mule 1.x will generally run without issues in JDK 5 since the JRE itself is backwards-compatible.