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new 0972954 CAMEL-16861: Cleanup and update EIP docs
0972954 is described below
commit 09729544ebf66e48b64868f1e75c5d7b0325568d
Author: Claus Ibsen <claus.ib...@gmail.com>
AuthorDate: Tue Oct 12 14:19:34 2021 +0200
CAMEL-16861: Cleanup and update EIP docs
---
.../main/docs/modules/eips/pages/hystrix-eip.adoc | 7 +-
.../docs/modules/eips/pages/resilience4j-eip.adoc | 105 +++++++++++----------
.../eips/pages/resilience4jConfiguration-eip.adoc | 5 +
3 files changed, 63 insertions(+), 54 deletions(-)
diff --git
a/core/camel-core-engine/src/main/docs/modules/eips/pages/hystrix-eip.adoc
b/core/camel-core-engine/src/main/docs/modules/eips/pages/hystrix-eip.adoc
index 9362092..8fc4506 100644
--- a/core/camel-core-engine/src/main/docs/modules/eips/pages/hystrix-eip.adoc
+++ b/core/camel-core-engine/src/main/docs/modules/eips/pages/hystrix-eip.adoc
@@ -3,8 +3,7 @@
The Hystrix EIP provides integration with Netflix
https://github.com/Netflix/Hystrix[Hystrix]
to be used as xref:circuitBreaker-eip.adoc[Circuit Breaker] in the Camel
routes.
-Hystrix is a latency and fault tolerance library designed to isolate points of
access to remote systems,
-services and 3rd party libraries, stop cascading failure and enable resilience
in complex distributed systems where failure is inevitable.
+Resilience4j is a lightweight fault tolerance library inspired by Netflix
Hystrix, but designed for functional programming.
== Configuration options
@@ -99,9 +98,9 @@ And in XML:
----
In this example if calling the downstream service does not return a response
within 2 seconds,
-a timeout is triggered, and the exchange will fail with a TimeoutException.
+a timeout is triggered, and the exchange will fail with a `TimeoutException`.
-== Camel's Error Handler and Circuit Breaker EIP
+=== Camel's Error Handler and Circuit Breaker EIP
By default, the xref:circuitBreaker-eip.adoc[Circuit Breaker] EIP handles
errors by itself.
This means if the circuit breaker is open, and the message fails, then Camel's
error handler
diff --git
a/core/camel-core-engine/src/main/docs/modules/eips/pages/resilience4j-eip.adoc
b/core/camel-core-engine/src/main/docs/modules/eips/pages/resilience4j-eip.adoc
index 9dddc74..5d9100a 100644
---
a/core/camel-core-engine/src/main/docs/modules/eips/pages/resilience4j-eip.adoc
+++
b/core/camel-core-engine/src/main/docs/modules/eips/pages/resilience4j-eip.adoc
@@ -1,23 +1,7 @@
= Resilience4j EIP
-This component supports the Circuit Breaker EIP with the Resilience4j library.
-
-[NOTE]
-====
-Camel provides the Circuit Breaker EIP in the route model, which allows to
plugin different implementations.
-Resilience4j is one such implementation.
-====
-
-Maven users will need to add the following dependency to their pom.xml to use
this EIP:
-
-[source]
-----
-<dependency>
- <groupId>org.apache.camel</groupId>
- <artifactId>camel-resilience4j</artifactId>
- <version>x.x.x</version><!-- use the same version as your Camel core
version -->
-</dependency>
-----
+The Resilience4j EIP provides integration with Resilience4j
https://resilience4j.readme.io/[Resilience4j]
+to be used as xref:circuitBreaker-eip.adoc[Circuit Breaker] in the Camel
routes.
== Configuration options
@@ -32,11 +16,14 @@ The Resilience4j EIP supports 2 options which are listed
below:
|===
// eip options: END
-See xref:resilience4jConfiguration-eip.adoc[Resilience4j Configuration] for
all the configuration options on Resilience Circuit Breaker.
+See xref:resilience4jConfiguration-eip.adoc[Resilience4j Configuration] for
all the configuration options
+on Resilience xref:circuitBreaker-eip.adoc[Circuit Breaker].
+
+== Using Resilienc4j EIP
-== Samples
+Below is an example route showing a Resilience4j circuit breaker
+that protects against a downstream HTTP operation with fallback.
-Below is an example route showing a Resilience endpoint that protects against
a downstream HTTP operation by falling back to the in-lined fallback route.
[source,java]
----
from("direct:start")
@@ -49,29 +36,35 @@ from("direct:start")
----
And in XML DSL:
+
[source,xml]
----
-<camelContext xmlns="http://camel.apache.org/schema/spring";>
- <route>
+<route>
<from uri="direct:start"/>
<circuitBreaker>
- <to uri="http://fooservice.com/faulty"/>
- <onFallback>
- <transform>
- <constant>Fallback message</constant>
- </transform>
- </onFallback>
+ <to uri="http://fooservice.com/faulty"/>
+ <onFallback>
+ <transform>
+ <constant>Fallback message</constant>
+ </transform>
+ </onFallback>
</circuitBreaker>
<to uri="mock:result"/>
- </route>
-</camelContext>
+</route>
----
-== Configuring Resilience4j
+In case the calling the downstream HTTP service is failing, and an exception
is thrown
+then the circuit breaker will react and execute the fallback route instead.
+
+If there was no fallback, then the circuit breaker will throw an exception.
+
+TIP: For more information about fallback see
xref:onFallback-eip.adoc[onFallback].
+
+=== Configuring Resilience4j
You can fine-tune Resilience4j by the many
xref:resilience4jConfiguration-eip.adoc[Resilience4j Configuration] options.
-For example to use a 2 second execution timeout, you can do as follows:
+For example to use 2 second execution timeout, you can do as follows:
[source,java]
----
@@ -80,7 +73,7 @@ from("direct:start")
// use 2 second timeout
.resilience4jConfiguration().timeoutEnabled(true).timeoutDuration(2000).end()
.log("Resilience processing start: ${threadName}")
- .toD("direct:${body}")
+ .to("http://fooservice.com/faulty";)
.log("Resilience processing end: ${threadName}")
.end()
.log("After Resilience ${body}");
@@ -95,30 +88,24 @@ And in XML:
<circuitBreaker>
<resilience4jConfiguration timeoutEnabled="true" timeoutDuration="2000"/>
<log message="Resilience processing start: ${threadName}"/>
- <toD uri="direct:${body}"/>
+ <to uri="http://fooservice.com/faulty"/>
<log message="Resilience processing end: ${threadName}"/>
</circuitBreaker>
<log message="After Resilience: ${body}"/>
</route>
----
-== Fallback
-
-See xref:onFallback-eip.adoc[onFallback].
-
-== Other examples
+In this example if calling the downstream service does not return a response
within 2 seconds,
+a timeout is triggered, and the exchange will fail with a `TimeoutException`.
-You can find an example with the source code:
https://github.com/apache/camel-spring-boot-examples/tree/master/camel-example-spring-boot-resilience4j[camel-example-spring-boot-resilience4j].
+=== Camel's Error Handler and Circuit Breaker EIP
-== Using Resilience4j with Spring Boot
+By default, the xref:circuitBreaker-eip.adoc[Circuit Breaker] EIP handles
errors by itself.
+This means if the circuit breaker is open, and the message fails, then Camel's
error handler
+is not reacting also.
-See the xref:components:others:resilience4j.adoc[Resilience4j Component].
-
-== Camel's Error Handler and Circuit Breaker EIP
-
-By default the Circuit Breaker EIP handles errors by itself. This means if the
circuit breaker is open and
-the message fails, then Camel's error handler is not reacting also.
-However, you can enable Camels error handler with circuit breaker by enabling
the `inheritErrorHandler` option, as shown:
+However, you can enable Camels error handler with circuit breaker by enabling
+the `inheritErrorHandler` option, as shown:
[source,java]
----
@@ -136,7 +123,7 @@ from("direct:start")
.to("mock:result");
----
-This example is from an unit test, where you can see the Circuit Breaker EIP
block has been hardcoded
+This example is from a test, where you can see the Circuit Breaker EIP block
has been hardcoded
to always fail by throwing an exception. Because the `inheritErrorHandler` has
been enabled,
then Camel's error handler will attempt to call the Circuit Breaker EIP block
again.
@@ -146,3 +133,21 @@ That means the `mock:a` endpoint will receive the message
again, and a total of
If we turn off the `inheritErrorHandler` option (default) then the Circuit
Breaker EIP will only be
executed once because it handled the error itself.
+== Dependencies
+
+[NOTE]
+====
+Camel provides the xref:circuitBreaker-eip.adoc[Circuit Breaker] EIP in the
route model, which allows to plugin different implementations.
+Resilience4j is one such implementation.
+====
+
+Maven users will need to add the following dependency to their pom.xml to use
this EIP:
+
+[source,xml]
+----
+<dependency>
+ <groupId>org.apache.camel</groupId>
+ <artifactId>camel-resilience4j</artifactId>
+ <version>x.x.x</version><!-- use the same version as your Camel core
version -->
+</dependency>
+----
diff --git
a/core/camel-core-engine/src/main/docs/modules/eips/pages/resilience4jConfiguration-eip.adoc
b/core/camel-core-engine/src/main/docs/modules/eips/pages/resilience4jConfiguration-eip.adoc
index 16946a8..88df8e0 100644
---
a/core/camel-core-engine/src/main/docs/modules/eips/pages/resilience4jConfiguration-eip.adoc
+++
b/core/camel-core-engine/src/main/docs/modules/eips/pages/resilience4jConfiguration-eip.adoc
@@ -5,7 +5,12 @@
:since:
:supportlevel: Stable
+This page documents all the specific options for the
xref:resilience4j-eip.adoc[Resilience4j] EIP.
// eip options: START
include::partial$eip-options.adoc[]
// eip options: END
+
+== Example
+
+See xref:resilience4j-eip.adoc[Resilience4j] EIP for details how to use this
EIP.
