/** * A marker interface for {@link org.quartz.JobDetail} s that * wish to have their state maintained between executions.  * StatefulJob instances follow slightly different rules from * regular Job instances. The key difference is that their * associated {@link JobDataMap} is re-persisted after every * execution of the job, thus preserving state for the next execution. The * other difference is that stateful jobs are not allowed to execute * concurrently, which means new triggers that occur before the completion of * the execute(xx) method will be delayed. * 
 *  * @see Job * @see JobDetail * @see JobDataMap * @see Scheduler *  * @author James House */public interface StatefulJob extends Job {     /*     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~     * Interface.     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~     */ }