Apache Camel 3.x Upgrade Guide

This document is for helping you upgrade your Apache Camel application from Camel 3.x to 3.y. For example if you are upgrading Camel 3.0 to 3.2, then you should follow the guides from both 3.0 to 3.1 and 3.1 to 3.2.

Upgrading Camel 3.4 to 3.5

FluentProducerTemplate

The template will now automatic clear its state when sending the message, this avoids end users having to call clearAll after usage, in case the template should be reused to send other messages.

After the template has been started / used the first time, then its general configuration cannot be altered later, instead create a new template.

PackageScanClassResolver

The PackageScanClassResolver will now skip abstract classes in its findImplementations method.

camel-bean

The bean(class) EIP will now lookup in the registry first whether there is a single bean instance of the given class type and use the existing bean (for singleton scope) instead of creating a new instance.

camel-cassandraql

Load-balancing policy has changed. There are no existing load balancing policies (see upgrade guide). To customize load balancing policy, please use the parameter loadBalancingPolicyClass and provide own implementation of load balancing policy.

Session impelentation class has changed from com.datastax.driver.core.Session to com.datastax.oss.driver.api.core.CqlSession (see upgrade guide). This could have direct impact on the type of parameter beanRef if you are using Provided Session reference.

There is a new parameter datacenter (with default value datacenter1). Data center has to be defined for the proper behavior of the default load balancing policy.

camel-sjms

The default value for keepAliveDelay was changed from -1 to 5000 in the batch jms consumer.

camel-weather

The option httpClient is now a query parameter.

A new parameter geoLocationProvider was introduced to allow the use of a custom GeolocationProvider implementation.

Camel Karaf

The following feature has been removed due to no longer being compatible with OSGi: camel-couchbase.

LifecycleStrategy

The LifecycleStrategy has been enhanced and provides some additional methods and changes in the behavior:

  • onContextInitializing: is invoked when the context is about to be initialized, this was previopusly achieved by onContextInitialized but as the name was a misleading

  • onContextInitialized: is now invoked when the context is initialized

  • onContextStarting: is invoked when the context is about to start, this was previously achieved by the onContextStart which is now deprecated.

  • onContextStarted: is now invoked when the context is started

  • onContextStopping: is invoked when the context is about to be stopped, this was previously achieved by the onContextStop which is now deprecated.

  • onContextStop: is now invoked when the context is stopped

JUnit 5 testing

Camel has been migrated from JUnit 4 to JUnit 5 as our default testing in all the components. The new test components reflect this with the following JAR names:

  • camel-test-junit5

  • camel-test-spring-junit5

  • camel-testcontainers-junit5

  • camel-testcontainers-spring-junit5

The older test components supports only JUnit 4.

Spring Boot testing with JUnit 5

Testing Camel on Spring Boot with JUnit 5 have also changed slightly to use JUnit 5 APIs and testing style.

The following set of dependencies can be used:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-test-spring-junit5</artifactId>
    <scope>test</scope>
</dependency>

Then in your test classes you should annotate the Spring Boot test class with the new @CamelSpringBootTest (from package org.apache.camel.test.spring.junit5.CamelSpringBootTest in camel-test-spring-junit5 JAR) annotation as shown:

@CamelSpringBootTest
@SpringBootTest(classes = MyCamelApplication.class)
public class MyCamelApplicationJUnit5Test {

    @Autowired
    private CamelContext camelContext;

    @Test
    public void shouldProduceMessages() throws Exception {
        // here you can write your unit test
    }

}
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