Testing distributed system

Question

Are there any java-based frameworks for testing distributed systems with JUnit or TestNG?

For instance I have a shared resource R and two clients (C_A, C_B) each connected to dedicated server (S_A, S_B). R can be used exclusively (one client at a time).

I want to make a test that checks simple scenario:

1. S_A starts up.
2. S_B starts up.
3. C_A logins on S_A.
4. C_B logins on S_B.
5. C_A tries to acquire R.
6. C_A acquires R.
7. C_B tries to acquire R.
8. C_B gets an appropriate exception instead of R.

What I need here is some kind of client-server framework with main machine as a director and several agents as executors. Main machine will perform the test using agents to host servers and clients.

Frameworks what I've seen lately (STAF, iValidator, JSystem) define distributed execution only in the sense of spreading testcases across test agents. But this is a simple load-balancing.

Thanks in advance.