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Subject [2/2] camel git commit: Added scheduler component docs to Gitbook
Date Wed, 15 Jun 2016 12:35:37 GMT
Added scheduler component docs to Gitbook


Branch: refs/heads/master
Commit: e5d910ab193abde3b59a3bf60305702aa1b692fb
Parents: 4ee85c0
Author: Andrea Cosentino <>
Authored: Wed Jun 15 14:34:51 2016 +0200
Committer: Andrea Cosentino <>
Committed: Wed Jun 15 14:34:51 2016 +0200

 camel-core/src/main/docs/scheduler.adoc | 181 +++++++++++++++++++++++++++
 docs/user-manual/en/          |   1 +
 2 files changed, 182 insertions(+)
diff --git a/camel-core/src/main/docs/scheduler.adoc b/camel-core/src/main/docs/scheduler.adoc
new file mode 100644
index 0000000..211e1aa
--- /dev/null
+++ b/camel-core/src/main/docs/scheduler.adoc
@@ -0,0 +1,181 @@
+Scheduler Component
+*Available as of Camel 2.15*
+The *scheduler:* component is used to generate message exchanges when a
+scheduler fires. This component is similar to the
+ link:timer.html[Timer] component, but it offers more functionality in
+terms of scheduling. Also this component uses
+JDK `ScheduledExecutorService`. Where as the timer uses a JDK `Timer`.
+You can only consume events from this endpoint.
+URI format
+Where `name` is the name of the scheduler, which is created and shared
+across endpoints. So if you use the same name for all your timer
+endpoints, only one scheduler thread pool and thread will be used - but
+you can configure the thread pool to allow more concurrent threads.
+You can append query options to the URI in the following format,
+*Note:* The IN body of the generated exchange is `null`. So
+`exchange.getIn().getBody()` returns `null`.
+// component options: START
+The Scheduler component supports 1 options which are listed below.
+{% raw %}
+| Name | Java Type | Description
+| concurrentTasks | int | Number of threads used by the scheduling thread pool. Is by default
using a single thread
+{% endraw %}
+// component options: END
+// endpoint options: START
+The Scheduler component supports 21 endpoint options which are listed below:
+{% raw %}
+| Name | Group | Default | Java Type | Description
+| name | consumer |  | String | *Required* The name of the scheduler
+| bridgeErrorHandler | consumer | false | boolean | Allows for bridging the consumer to the
Camel routing Error Handler which mean any exceptions occurred while the consumer is trying
to pickup incoming messages or the likes will now be processed as a message and handled by
the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler
to deal with exceptions that will be logged at WARN/ERROR level and ignored.
+| sendEmptyMessageWhenIdle | consumer | false | boolean | If the polling consumer did not
poll any files you can enable this option to send an empty message (no body) instead.
+| exceptionHandler | consumer (advanced) |  | ExceptionHandler | To let the consumer use
a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this options
is not in use. By default the consumer will deal with exceptions that will be logged at WARN/ERROR
level and ignored.
+| pollStrategy | consumer (advanced) |  | PollingConsumerPollStrategy | A pluggable org.apache.camel.PollingConsumerPollingStrategy
allowing you to provide your custom implementation to control error handling usually occurred
during the poll operation before an Exchange have been created and being routed in Camel.
In other words the error occurred while the polling was gathering information for instance
access to a file network failed so Camel cannot access it to scan for files. The default implementation
will log the caused exception at WARN level and ignore it.
+| exchangePattern | advanced | InOnly | ExchangePattern | Sets the default exchange pattern
when creating an exchange.
+| synchronous | advanced | false | boolean | Sets whether synchronous processing should be
strictly used or Camel is allowed to use asynchronous processing (if supported).
+| backoffErrorThreshold | scheduler |  | int | The number of subsequent error polls (failed
due some error) that should happen before the backoffMultipler should kick-in.
+| backoffIdleThreshold | scheduler |  | int | The number of subsequent idle polls that should
happen before the backoffMultipler should kick-in.
+| backoffMultiplier | scheduler |  | int | To let the scheduled polling consumer backoff
if there has been a number of subsequent idles/errors in a row. The multiplier is then the
number of polls that will be skipped before the next actual attempt is happening again. When
this option is in use then backoffIdleThreshold and/or backoffErrorThreshold must also be
+| concurrentTasks | scheduler | 1 | int | Number of threads used by the scheduling thread
pool. Is by default using a single thread
+| delay | scheduler | 500 | long | Milliseconds before the next poll. The default value is
500. You can also specify time values using units such as 60s (60 seconds) 5m30s (5 minutes
and 30 seconds) and 1h (1 hour).
+| greedy | scheduler | false | boolean | If greedy is enabled then the ScheduledPollConsumer
will run immediately again if the previous run polled 1 or more messages.
+| initialDelay | scheduler | 1000 | long | Milliseconds before the first poll starts. The
default value is 1000. You can also specify time values using units such as 60s (60 seconds)
5m30s (5 minutes and 30 seconds) and 1h (1 hour).
+| runLoggingLevel | scheduler | TRACE | LoggingLevel | The consumer logs a start/complete
log line when it polls. This option allows you to configure the logging level for that.
+| scheduledExecutorService | scheduler |  | ScheduledExecutorService | Allows for configuring
a custom/shared thread pool to use for the consumer. By default each consumer has its own
single threaded thread pool. This option allows you to share a thread pool among multiple
+| scheduler | scheduler | none | ScheduledPollConsumerScheduler | Allow to plugin a custom
org.apache.camel.spi.ScheduledPollConsumerScheduler to use as the scheduler for firing when
the polling consumer runs. The default implementation uses the ScheduledExecutorService and
there is a Quartz2 and Spring based which supports CRON expressions. Notice: If using a custom
scheduler then the options for initialDelay useFixedDelay timeUnit and scheduledExecutorService
may not be in use. Use the text quartz2 to refer to use the Quartz2 scheduler; and use the
text spring to use the Spring based; and use the text myScheduler to refer to a custom scheduler
by its id in the Registry. See Quartz2 page for an example.
+| schedulerProperties | scheduler |  | Map | To configure additional properties when using
a custom scheduler or any of the Quartz2 Spring based scheduler.
+| startScheduler | scheduler | true | boolean | Whether the scheduler should be auto started.
+| timeUnit | scheduler | MILLISECONDS | TimeUnit | Time unit for initialDelay and delay options.
+| useFixedDelay | scheduler | true | boolean | Controls if fixed delay or fixed rate is used.
See ScheduledExecutorService in JDK for details.
+{% endraw %}
+// endpoint options: END
+More information
+This component is a scheduler
+[Polling Consumer] where
+you can find more information about the options above, and examples at
+Consumer] page.
+Exchange Properties
+When the timer is fired, it adds the following information as properties
+to the `Exchange`:
+|Name |Type |Description
+|`Exchange.TIMER_NAME` |`String` |The value of the `name` option.
+|`Exchange.TIMER_FIRED_TIME` |`Date` |The time when the consumer fired.
+To set up a route that generates an event every 60 seconds:
+   from("scheduler://foo?period=60s").to("bean:myBean?method=someMethodName");
+The above route will generate an event and then invoke the
+`someMethodName` method on the bean called `myBean` in the
+link:registry.html[Registry] such as JNDI or link:spring.html[Spring].
+And the route in Spring DSL:
+  <route>
+    <from uri="scheduler://foo?period=60s"/>
+    <to uri="bean:myBean?method=someMethodName"/>
+  </route>
+Forcing the scheduler to trigger immediately when completed
+To let the scheduler trigger as soon as the previous task is complete,
+you can set the option greedy=true. But beware then the scheduler will
+keep firing all the time. So use this with caution.
+Forcing the scheduler to be idle
+There can be use cases where you want the scheduler to trigger and be
+greedy. But sometimes you want "tell the scheduler" that there was no
+task to poll, so the scheduler can change into idle mode using the
+backoff options. To do this you would need to set a property on the
+exchange with the key `Exchange.SCHEDULER_POLLED_MESSAGES` to a boolean
+value of false. This will cause the consumer to indicate that there was
+no messages polled. 
+The consumer will otherwise as by default return 1 message polled to the
+scheduler, every time the consumer has completed processing the
+See Also
+* link:configuring-camel.html[Configuring Camel]
+* link:component.html[Component]
+* link:endpoint.html[Endpoint]
+* link:getting-started.html[Getting Started]
+* link:timer.html[Timer]
+* link:quartz.html[Quartz]
diff --git a/docs/user-manual/en/ b/docs/user-manual/en/
index 9e6c8cc..7efa196 100644
--- a/docs/user-manual/en/
+++ b/docs/user-manual/en/
@@ -90,6 +90,7 @@
     * [Properties](properties.adoc)
     * [Ref](ref.adoc)
     * [Rest](rest.adoc)
+    * [Scheduler](scheduler.adoc)
 * Components
     * [Async Http Client (AHC)](ahc.adoc)

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