DistributedLocking.java demonstrates the user of distributed locking to
manage concurrent access to resources. In this case, the resource used is a
distributed, non-global data region, but it could be a file or any other
resource whose use is contended. The program creates a named lock service and
then tries 5 times to get a lock from it. Each time it succeeds, it updates a
key in the region and reports the update to the screen. This program is
intended to be run as two concurrent runs, so there is contention created for
the lock. See the quickstart guide for run instructions.