Hi Hari Kumar,
I think what you do should be ok.
Try to look at the implementation of org.jbpm.process.workitem.wsht.GenericHTWorkItemHandler at code line around 185.
There the Work Item Handler can be confirgured to three kind of action when an exception occured:
1. Abort the work item, and the process will continue
2. Throw new Exception (and the process should rollback or stop at that node)
3. Log the error
Another option is to complete the workitem with output that will trigger the alternate flow path.
btw, you should open a new thread for this as others will be able to see your question and help too.
Regards,
Thomas Setiabudi