SMG Internal Presentation

1. Quartz Scheduler

2. About
• «Quartz is a richly featured, open source job scheduling library that
can be integrated within virtually any Java application»
• First Release 10/Apr/09 --
https://jira.terracotta.org/jira/browse/QTZ?selectedTab=com.atlassia
n.jira.jira-projects-plugin:changelog-panel&allVersions=true
• https://github.com/quartz-scheduler/quartz
• http://www.quartz-scheduler.org/

3. Features
• Runtime Environments
• Job Scheduling
• Job Execution
• Job Persistence
• Transactions
• Clustering
• Listeners & Plug-Ins

4. Runtime Environments
• Quartz, can run embeded within another Standalone Application
• Can be instantiated within an application server(or servlet
container), and participate XA transactions.
• Can run as a stand-alone program, to be used via RMI
• Can be instantiated as a cluster

5. Job Scheduling
• at a certain time of day (to the millisecond)
• on certain days of the week
• on certain days of the month
• on certain days of the year
• not on certain days listed within a registered Calendar (such as
business holidays)
• repeated a specific number of times
• repeated until a specific time/date
• repeated indefinitely
• repeated with a delay interval

6. Job Execution
• Jobs can be any Java class that implements Job interface
• Job and TriggerListener can be notified
• Actions can be instructed according to returncode such as immediate
re-execution of the Job

7. Job Persistance
• Storage of jobs and triggers
• RAMJobStore
• JDBCJobStore(Container Managed Transactions, Unmanaged)
• Terracota Job Store(without need for a backing DB)

8. Transactions
• Can participate in JTA transactions
• Can manage Transactions(works for all jobs or per job with
@ExecuteInJTATransaction Annotation)

9. Clustering
• Fail-over
• Load Balancing
• Quartz’s built-in clustering features rely upon database persistence
via JDBCJobStore.
• Terracotta extensions to Quartz provide clustering capabilities
without the need for a backing database.

10. Listeners & Plug-Ins
• Applications can catch scheduling events to monitor or control
job/trigger behavior by implementing one or more listener interfaces.
• The Plug-In mechanism can be used add functionality to Quartz, such
keeping a history of job executions, or loading job and trigger
definitions from a file.
• Quartz ships with a number of “factory built” plug-ins and listeners.

11. The Quartz API
• Scheduler - the main API for interacting with the scheduler.
• Job - an interface to be implemented by components that you wish to
have executed by the scheduler.
• JobDetail - used to define instances of Jobs.
• Trigger - a component that defines the schedule upon which a given
Job will be executed.
• JobBuilder - used to define/build JobDetail instances, which define
instances of Jobs.
• TriggerBuilder - used to define/build Trigger instances.

12. The Quartz API

13. org.quartz.Scheduler
• Add/delete/update/list Jobs
• Schedule/pause/resume triggers
• Start/shutdown
• Register calendars

14. Jobs And Job Details
• Job.execute(JobExecutionContext context)
• JobDetail
• jobClass
• durability
• requestsRecovery
• description
• key
• jobDataMap
• JobDataMap->Map<String,? Extends Serializable>
• Only usage of primitiveTypes and String is encourged.(Class-versioning problems
can occur with serialized Objects)

15. Job – Instances,State and Concurrency
• JobDetail -> «job» or «job definition»
• Each Execution of a Job Detail -> «Job Instance»
• A Class implements org.quartz.Job -> «job class»
• A new instance of the job class is created for each execution
• @DisallowConcurrentExecution -> an annotation on a Job Class. Tell
Quartz not to execute multiple instances of a given job definition
concurrently.
• @PersistJobDataAfterExecution -> update the stored copy of
JobDetail’s JobDataMap.

16. Job – Durability,RequestRecovery
• Durability -> if a job is non-durable, it is automatically deleted from
the scheduler once there are no longer active triggers associated with
it.
• RequestRecovery -> if a job “requests recovery”, and it is executing
during the time of a ‘hard shutdown’ of the scheduler (i.e. the
process it is running within crashes, or the machine is shut off), then
it is re-executed when the scheduler is started again. In this case, the
JobExecutionContext.isRecovering() method will return true.

17. Job – JobExecutionException
• Only type of exception can be thrown from Job.execute method.
• Can be interpreted as directives to Scheduler.
• RE_EXECUTE_JOB
• SET_TRIGGER_COMPLETE
• SET_ALL_JOB_TRIGGERS_COMPLETE

18. Trigger – Common Trigger Attributes
• jobKey
• startTime
• endTime
• priority -> nextexecutionTime ASC, priority DESC
• MisFire Instructions
• Calendars -> e.g. Business’s Holidays

19. Trigger – Simple Trigger
• repeatCount
• repeatInterval
• startTime
• endTime

20. Trigger – Simple Trigger – Misfire Instructions
• IGNORE_MISFIRE_POLICY
• FIRE_NOW
• RESCHEDULE_NOW_WITH_EXISTING_REPEAT_COUNT
• RESCHEDULE_NOW_WITH_REMAINING_REPEAT_COUNT
• NEXT_WITH_REMAINING_COUNT
• NEXT_WITH_EXISTING_COUNT

21. Trigger – Cron Trigger
• Cron Expressions
• Seconds -> 0..59 | 0/5 |0-5 |0,5
• Minutes -> 0..59 | 5/7 |0-5 |0,5
• Hours -> 0..23 | 5/7 |0-5 |0,5
• Day-of-Month -> 1..31 |1-5 |1,5 | ? | * |L |L-3|15W
• Month -> 0..11 |0-5 |0,5 | JAN | JAN-JUL
• Day-of-Week -> 1..7 |SUN-SAT|1-4|?|*|L|6L|FRIL|FRI#3
• Year(Optional)

22. Trigger – Cron Trigger – MisFire Instructions
• IGNORE_MISFIRE_POLICY
• DO_NOTHING
• FIRE_NOW

23. Listeners – Job, Trigger Listener
• Registered with the Scheduler.ListenerManager
• Not Stored in the Job Store. Need to be re-registered in each run

24. Listeners – Scheduler Listener

25. JobStores
• RAMJobStore
• JDBCJobStore
• TerracottaJobStore

26. JobStores - RAMJobStore
• The simplest JobStore to use
• The most performant(in terms of CPU time)
• Keeps all of its data in RAM
• When the application ends (or crashes) all of the scheduling
information is lost
• Config -> org.quartz.jobStore.class = org.quartz.simpl.RAMJobStore

27. JobStores – JDBCJobStore
• Keeps all of its data in a database via JDBC
• Works with nearly any database
• Table-creation SQL scripts are shipped with the
distribution.(docs/dbTables)
• All the tables start with the prefix(default QRTZ) which can be changed
(org.quartz.jobStore.tablePrefix = SMG_)
• JobStoreTX -> Quartz Managed Transactions
• JobStoreCMT -> Container Managed Transactions
• org.quartz.jobStore.class = org.quartz.impl.jdbcjobstore.JobStoreTX
• org.quartz.jobStore.class = org.quartz.impl.jdbcjobstore.JobStoreCMT

28. JobStores – JDBCJobStore

29. JobStores – TerracotaJobStore
• Scaling and robustness without the use of a database
• Not open-source

30. ThreadPool
• Default org.quartz.simpl.SimpleThreadPool
• Maintains a fixed set of threads in its pool
• Never grows, never shrinks
• «Quite robust and is very well tested»

31. Logging
• Uses the SLF4J Framework
• Plugins can be enabled for capturing extra information about trigger
firings and job executions.
• org.quartz.plugins.history.LoggingJobHistoryPlugin
• org.quartz.plugins.history.LoggingTriggerHistoryPlugin

32. Clustering
• Works with the JDBC-Jobstore and TerracottaJobStore
• Clustering on seperate machines needs clock synchronization.
• Each instance in the cluster should use the same copy of the
quartz.properties
• Exceptions:
• Different Thread Pool Size
• InstanceId
• Only one node will fire the job for each firing.

33. Clustering – Properties

34. Clustering

35. Clustering

36. FAQ
• How do I chain Job execution? How do I create a workflow?
• There currently is no "direct" or "free" way to chain triggers with Quartz
• What are the available alternatives to Quartz?
• There are no known competing open source projects
• Commercially, you will want to look at the well-regarded Flux scheduler.

37. EXAMPLES

38. Questions