Asynchronous Job Processing Using Quartz.Net

1. Asynchronous Job ProcessingUsing Quartz.Net Jay Vilalta jay.vilalta@gmail.com

2. What Is Quartz.Net • Scheduler (think task scheduler) • Queue for asynchronous jobs • C# port of Quartz (java) • Apache license

3. Why Use Quartz.Net • Scale out • Redundancy • Smart handling of failures • Job chaining (poor man’s workflow) • Custom scheduling

4. How Can I Run It • Embedded in your application • As a stand alone windows service

5. The Basics • Scheduler • Jobs • Triggers

6. Scheduler • Runs jobs • Manages the scheduling

7. Jobs • Do the work • Some built-in • Mostly roll you own • Implement IJob

8. Built-in Jobs • FileScanJob: monitors last modified date • NativeJob: runs executables or batch files • NoOpJob: does nothing • SendMailJob: sends emails

9. Jobs - Example public class MyJob : IJob { public void Execute(JobExecutionContext context) { try { int count= context.MergedJobDataMap.GetIntegerFromString(“count"); for (int i = 0; i < count; i++){ //do something useful } } catch (ApplicationException ex) { throw new JobExecutionException("Something happened", ex, false); } } }

10. Triggers • Tell the scheduler when jobs should run • Some built-in • Simple Trigger • Cron Trigger • NthIncludedDayTrigger • Custom Triggers

11. Simple Trigger • Start Time • Repeat Count • Repeat Interval

12. Cron Trigger • Similar to UNIX cron • Start Time • Cron Expression • “0 15 10 ? * *” • “0 0,15,30,45 * ? * *”

13. Custom Triggers • No example this time • Implementing a trigger is not trivial • Must implement 11 methods • Must be able to determine next fire time

14. Scheduling • Associate a job to a trigger • Multiple triggers can be set • When the trigger fires, the job runs scheduler.ScheduleJob(jobDetail, trigger);

15. Advanced Features • Listeners • Special Jobs • Remote management • Clustering • Plug-ins • Unit testing

16. Listeners • Job Listeners • Trigger Listeners • Scheduler Listeners • Job and trigger listeners can be global

17. Job Listener Example public class JobHistoryListener : IJobListener { public void JobExecutionVetoed(…) public void JobToBeExecuted(…) public void JobWasExecuted(…) }

18. Trigger Listener Example public class MyTriggerListener:ITriggerListener { public string Name public void TriggerComplete(…) public void TriggerFired(…) public void TriggerMisfired(…) public bool VetoJobExecution(…) }

19. Special Jobs • Stateful Jobs • Interruptible Jobs

20. Stateful Jobs • Only one can run at a time • Allow you to save/restore state • You must manage state yourself • Implement IStatefulJob

21. Interruptible Jobs • Mechanism to interrupt long running jobs • You must implement yourself • Implement IInterruptableJob

22. Remote Management • Scheduler can be managed remotely • Exposed via Remoting • Most scheduler functions available

23. JobFactory • Instantiates jobs • Default factory creates a new instance • Create your own if you use DI or IoC container

24. Job Stores • RAMJobStore • AdoJobStore • MySql • Oracle • Postgres • SQL Lite • SQL Server

25. Clustering • Load balancing • Job Failover • Caveat: clocks synchronized within a second

26. Plug-ins • JobInitializationPlugin • LoggingJobHistoryPlugin • LoggingTriggerHisotryPlugin • ShutdownHookPlugin

27. Plug-ins Stub public class SamplePlugin : ISchedulerPlugin { public void Initialize(string name, IScheduler sched) public void Shutdown() public void Start() }

28. Unit Testing • You can / should unit test your quartz classes • Use a mocking framework • Mock the Scheduler (IScheduler) • Mock a calendar (ICalendar) • Use mocks to create your context

29. Sample Unit Test [Test] public void ExecuteTests() { JobDetail detail = new JobDetail(); IScheduler scheduler = new Mock<IScheduler>().Object; ICalendar calendar = new Mock<ICalendar>().Object; IJob job = new NoOpJob(); detail.Name = "Test"; detail.JobDataMap.Add("SOMETHING", "ELSE"); TriggerFiredBundle bundle = new TriggerFiredBundle(detail, new SimpleTrigger(), calendar, false, null, null, null, null); JobExecutionContext context = new JobExecutionContext(scheduler, bundle, job); JobHistoryListener listener = new JobHistoryListener(); listener.JobToBeExecuted(context); listener.JobWasExecuted(context, null); //methods return void so need to get creative to determine if execution was successful } }

30. Resources Project Home: http://quartznet.sourceforge.net/ Mailing List: http://groups.google.com/group/quartznet Getting Started: http://jvilalta.blogspot.com