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Maven users will need to add the following dependency to their their pom.xml for to use this EIP:

Code Block

	xml
	xml

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-hystrix</artifactId>
    <version>x.x.x</version><!-- use the same version as your Camel core version -->
</dependency>

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a strategy the the a .This property determines whether a call to HystrixCommand.getFallback() will be attempted when failure or rejection occurs6 rollingPercentile will be 10 number of buckets the rolling statistical window is divided into

Name	Default Value	Type	Description
commandKey	Node id	String	Used to identify the hystrix command. This option cannot be configured but is locked down to be the node id to make the command unique.
groupKey	CamelHystrix	String	Used to identify the hystrix group being used by the EIP to correlate statistics, circuit-breaker, properties, etc.
threadPoolKey	null	String	Used to define which thread-pool this command should run in. By default this is using the same key as the group key.
corePoolSize	10	Integer	This property sets the core thread-pool size. This is the maximum number of HystrixCommands that can execute concurrently.
keepAliveTime	1	Integer	This property sets the keep-alive time, in minutes.
maxQueueSize	-1	Integer	This property sets the maximum queue size of the BlockingQueue implementation.
queueSizeRejectionThreshold	5	Integer	This property sets the queue size rejection threshold — an artificial maximum queue size at which rejections will occur even if maxQueueSize has not been reached.
threadPoolMetricsRollingStatisticalWindowInMilliseconds	10000	Integer	This property sets the duration of the statistical rolling window, in milliseconds. This is how long metrics are kept for the thread pool.
threadPoolMetricsRollingStatisticalWindowBuckets	10	Integer	This property sets the number of buckets the rolling statistical window is divided into.
`circuitBreakerEnabled`	`true`	`Boolean`	This property determines whether a circuit breaker will be used to track health and to short-circuit requests if it trips.
`circuitBreakerErrorThresholdPercentage`	`50`	`Integer`	This property sets the error percentage at or above which the circuit should trip open and start short-circuiting requests to fallback logic.
`circuitBreakerForceClosed`	`false`	`Boolean`	This property, if true, forces the circuit breaker into a closed state in which it will allow requests regardless of the error percentage.
`circuitBreakerForceOpen`	`false`	`Boolean`	This property, if true, forces the circuit breaker into an open (tripped) state in which it will reject all requests.
`circuitBreakerRequestVolumeThreshold`	`20`	`Integer`	This property sets the minimum number of requests in a rolling window that will trip the circuit.
`circuitBreakerSleepWindowInMilliseconds`	`5000`	`Integer`	This property sets the amount of time, after tripping the circuit, to reject requests before allowing attempts again to determine if the circuit should again be closed.
`commandKey`	`Node id`	`String`	Used to identify the hystrix command. This option cannot be configured but is locked down to be the node id to make the command unique.
`corePoolSize`	`10`	`Integer`	This property sets the core thread-pool size. This is the maximum number of `HystrixCommands` that can execute concurrently.
`executionIsolationSemaphoreMaxConcurrentRequests`	`10`	`Integer`	This property sets the maximum number of requests allowed to	a `HystrixCommand.run()` method when you are using `ExecutionIsolationStrategy.SEMAPHORE`. If this maximum concurrent limit is hit then subsequent requests will be rejected.
`executionIsolationStrategy`	`THREAD`	`String`	This property indicates which isolation	strategy `HystrixCommand.run()` executes with, one of the following two choices: `THREAD` — it executes on a separate thread and concurrent requests are limited by the number of threads in the thread-pool `SEMAPHORE` — it executes on the calling thread and concurrent requests are limited by the semaphore count
`executionIsolationThreadInterruptOnTimeout`	`true`	`Boolean`	This property indicates whether	the `HystrixCommand.run()` execution should be interrupted when a timeout occurs.
`executionTimeoutInMilliseconds`	`1000`	`Integer`	This property sets the time in milliseconds after which the caller will observe a timeout and walk away from the command execution.
`executionTimeoutEnabled`	`true`	`Boolean`	This property indicates whether	the `HystrixCommand.run()` execution should have a timeout.
`fallbackEnabled`	`true`	`Boolean`	This property determines whether a call to `HystrixCommand.getFallback()` will be attempted when failure or rejection occurs.
`fallbackIsolationSemaphoreMaxConcurrentRequests`	`10`	`Integer`	This property sets the maximum number of requests	a `HystrixCommand.getFallback()` method is allowed to make from the calling thread	fallbackEnabled	true	Boolean	.
`groupKey`	`CamelHystrix`	`String`	Used to identify the hystrix group being used by the EIP to correlate statistics, circuit-breaker, properties, etc.
`keepAliveTime`	`1`	`Integer`	This property sets the keep-alive time, in minutes.
`maxQueueSize`	`-1`	`Integer`	This property sets the maximum queue size of the `BlockingQueue` implementation.
`metricsHealthSnapshotIntervalInMilliseconds`	`500`	`Integer`	This property sets the time to wait, in milliseconds, between allowing health snapshots to be taken that calculate success and error percentages and affect circuit breaker status.
`metricsRollingPercentileBucketSize`	`100`	`Integer`	This property sets the maximum number of execution times that are kept per bucket. If more executions occur during the time they will wrap around and start over-writing at the beginning of the bucket.
`metricsRollingPercentileEnabled`	`true`	`Boolean`	This property indicates whether execution latencies should be tracked and calculated as percentiles. If they are disabled, all summary statistics (mean, percentiles) are returned as -1.
`metricsRollingPercentileWindowBuckets`	`6`	`Integer`	This property sets the number of buckets the rollingPercentile window will be divided into.
`metricsRollingPercentileWindowInMilliseconds`	`60000`	`Integer`	This property sets the duration of the rolling window in which execution times are kept to allow for percentile calculations, in milliseconds.metricsRollingPercentileWindowBuckets
`metricsRollingStatisticalWindowBuckets`	`10`	`Integer`	This property sets the number of buckets the	rolling statistical window	is divided into.
`metricsRollingStatisticalWindowInMilliseconds`	`10000`	`Integer`	The following properties are related to capturing metrics from from `HystrixCommand` and and `HystrixObservableCommand` execution.metricsRollingStatisticalWindowBuckets
`queueSizeRejectionThreshold`	`5`	`Integer`	This property sets the	queue size rejection threshold — an artificial maximum queue size at which rejections will occur even if `maxQueueSize` has not been reached.
`requestLogEnabled`	`true`	`Boolean`	This property indicates whether whether `HystrixCommand` execution and events should be logged to `HystrixRequestLog`.
`threadPoolKey`	`null`	`String`	Used to define which thread-pool this command should run in. By default this is using the same key as the group key.
`threadPoolMetricsRollingStatisticalWindowBuckets`	`10`	`Integer`	This property sets the number of buckets the rolling statistical window is divided into.
`threadPoolMetricsRollingStatisticalWindowInMilliseconds`	`10000`	`Integer`	This property sets the duration of the statistical rolling window, in milliseconds. This is how long metrics are kept for the thread pool.

Example

Below is an example route that with showing an Hystrix endpoint that protects agains against slow operation and fallbacks by falling back to the inlined in-lined fallback route. By default the timeout request is just 1000 millis (1 sec) just 1000ms so the http HTTP endpoint has to be fairly quick to succeed.

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onFallback vs onFallbackViaNetwork

If you are using using onFallback then that is intended to be local processing only where you can do a message transformation or call a bean or something as the fallback. If you need to call an external service over the network then you should use use onFallbackViaNetwork that runs in another indepedent independent HystrixCommand that uses its own thread pool to not exhaust the first command.

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Hystrix has many options as listed in the table above. For example to set a higher timeout to to 5 seconds, and also let the circuit breaker wait wait 10 seconds before attempting a request again when the state was tripped to be open.

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Versions Compared

Old Version 6

New Version 7

Key

Example

onFallback vs onFallbackViaNetwork