Hi Tun,
There is a List<String> getTransitionNames(); method in HistoryActivityInstance, you could use this to get the name of next transition. If you want to get the name of incoming node, I am afraid you have to write some codes by yourself.
BTW, Maciej is working on some stuff like this. If you have any advices please join our discussion. Thank you very much.
http://community.jboss.org/thread/154420?tstart=0