Quartz is an open source job scheduling library that can be integrated with Java applications. It allows scheduling of jobs to run at specific times, intervals, or based on a cron expression. Jobs are defined as Java classes and can be persisted in memory, a database like PostgreSQL, or with Terracotta for clustering. Triggers determine when and how often jobs are executed. Quartz provides listeners and plugins to monitor and customize job behavior.

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