jtrag is is a small, standalone java library on top of jtwfg. It adds a "task resource assignment graph" API.
The typical use case for someone is having some kind of own "execution engine" implementation (local, distributed, grid…) with some kind of tasks and resources in it, with optional dependencies between the tasks and resources. Someone wants to be able to easily detect deadlocks in his/her engine.
jtrag together with jtwfg implements a graph model with a deadlock detection algorithm.
To use the jtrag/jtwfg deadlock detection, you transform your "execution engine" domain model objects into jtrag/jtwfg graph model objects and call then the jtwfg deadlock detector.