For single-action or interval timers, the expiration of the timer can be expressed as either a duration or an absolute time. The duration is expressed as a the number of milliseconds before a timeout event is triggered. To specify an absolute time, create a java.util.Date object and pass it to the TimerService.createSingleActionTimer or the TimerService.createTimer method.
The following code sets a programmatic timer that will expire in 1 minute (6,000 milliseconds):
long duration = 6000; Timer timer = timerService.createSingleActionTimer(duration, new TimerConfig());
The following code sets a programmatic timer that will expire at 12:05 p.m. on May 1, 2010, specified as a java.util.Date:
SimpleDateFormatter formatter = new SimpleDateFormatter("MM/dd/yyyy 'at' HH:mm"); Date date = formatter.parse("05/01/2010 at 12:05"); Timer timer = timerService.createSingleActionTimer(date, new TimerConfig());
For calendar-based timers, the expiration of the timer is expressed as a javax.ejb.ScheduleExpression object, passed as a parameter to the TimerService.createCalendarTimer method. The ScheduleExpression class represents calendar-based timer expressions and has methods that correspond to the attributes described in Creating Calendar-Based Timer Expressions.
The following code creates a programmatic timer using the ScheduleExpression helper class:
ScheduleExpression schedule = new ScheduleExpression(); schedule.dayOfWeek("Mon"); schedule.hour("12-17, 23"); Timer timer = timerService.createCalendarTimer(schedule);
For details on the method signatures, see the TimerService API documentation at http://download.oracle.com/javaee/6/api/javax/ejb/TimerService.html.
The bean described in The timersession Example creates a timer as follows:
Timer timer = timerService.createTimer(intervalDuration, "Created new programmatic timer");
In the timersession example, createTimer is invoked in a business method, which is called by a client.
Timers are persistent by default. If the server is shut down or crashes, persistent timers are saved and will become active again when the server is restarted. If a persistent timer expires while the server is down, the container will call the @Timeout method when the server is restarted.
Nonpersistent programmatic timers are created by calling TimerConfig.setPersistent(false) and passing the TimerConfig object to one of the timer-creation methods.
The Date and long parameters of the createTimer methods represent time with the resolution of milliseconds. However, because the timer service is not intended for real-time applications, a callback to the @Timeout method might not occur with millisecond precision. The timer service is for business applications, which typically measure time in hours, days, or longer durations.