JTR (Java Test Runner) is a framework meant for fastening the building of both complex and simple test enviroments. It is based on concepts such as Inversion of Control, and is ready for EJB and JMS testing.
The JTR 2.0 framework will give you the chance to code only the testing logic. All the boring middleware-related tasks (connecting to ConnectionFactories, opening connections, sharing connections, opening sessions, handleing exceptions, retrieving administered objects) are carried out by the JTR 2.0 runtime on your behalf according to what you have stated in the jtr.xml configuration file.
Thanks to IoC (Inversion Of Control), the JTR 2.0 runtime is able to inject all these resources into your IRunner concrete implementations. This entails that you are not required to actively retrieve the resources you need: you declaratively tell the JTR 2.0 framework you are going to need them at runtime, and Inversion Of Control will do the work.
The thing same happens with EJBs: all the low-level details are always handled by the JTR framework to let you work only on the pure logic of your tests.