Chapter 2. Migrating to Apache Camel 4

The polled endpoint URI is now stored as property on the Exchange (with key CamelToEndpoint) like all other EIPs. Before the URI was stored as a message header.

The following options in camel-resilience4j was mistakenly not defined as attributes:

These options were not exposed in YAML DSL, and in XML DSL you need to migrate from:

<circuitBreaker>
    <resilience4jConfiguration>
        <timeoutEnabled>true</timeoutEnabled>
        <timeoutDuration>2000</timeoutDuration>
    </resilience4jConfiguration>
...
</circuitBreaker>

<circuitBreaker>
    <resilience4jConfiguration>
        <timeoutEnabled>true</timeoutEnabled>
        <timeoutDuration>2000</timeoutDuration>
    </resilience4jConfiguration>
...
</circuitBreaker>

To use following attributes instead:

<circuitBreaker>
    <resilience4jConfiguration timeoutEnabled="true" timeoutDuration="2000"/>
...
</circuitBreaker>

<circuitBreaker>
    <resilience4jConfiguration timeoutEnabled="true" timeoutDuration="2000"/>
...
</circuitBreaker>

The option camel.health.components-enabled has been renamed to camel.health.producers-enabled.

Some components (in particular AWS) provides also health checks for producers; in Camel 3.x these health checks did not work properly and has been disabled in the source. To continue this behaviour in Camel 4, the producer based health checks are disabled.

Notice that camel-kafka comes with producer based health-check that worked in Camel 3, and therefore this change in Camel 4, means that this health-check is disabled.

You MUST enable producer health-checks globally, such as in application.properties:

camel.health.producers-enabled = true

camel.health.producers-enabled = true

The number of enums for org.apache.camel.Category has been reduced from 83 to 37, which means custom components that are using removed values need to choose one of the remainder values. We have done this to consolidate the number of categories of all components in the Camel community.

This dsl-generator has updated the underlying model classes (apicurio-data-models) from 1.1.27 to 2.0.3.

The camel-atom component has changed the 3rd party atom client from Apache Abdera to RSSReader. This means the feed object is changed from org.apache.abdera.model.Feed to com.apptasticsoftware.rssreader.Item.

The itemPartitionKey has been updated. It’s now a String a not a PartitionKey anymore. More details in CAMEL-19222.

When using the method option to refer to a specific method, and using parameter types and values, such as: "bean:myBean?method=foo(com.foo.MyOrder, true)" then any class types must now be using .class syntax, i.e. com.foo.MyOrder should now be com.foo.MyOrder.class.

"bean:myBean?method=foo(com.foo.MyOrder.class, true)"

"bean:myBean?method=foo(com.foo.MyOrder.class, true)"

This also applies to Java types such as String, int.

"bean:myBean?method=bar(String.class, int.class)"

"bean:myBean?method=bar(String.class, int.class)"

Upgraded from Box Java SDK v2 to v4, which have some method signature changes. The method to get a file thumbnail is no longer available.

The keyType parameter has been removed. The Key for the cache will now be only String type. More information in CAMEL-18877.

The underlying hapi-fhir library has been upgraded from 4.2.0 to 6.2.4. Only the Delete API method has changed and now returns ca.uhn.fhir.rest.api.MethodOutcome instead of org.hl7.fhir.instance.model.api.IBaseOperationOutcome. See hapi-fhir for a more detailed list of underlying changes (only the hapi-fhir client is used in Camel).

The API based components camel-google-drive, camel-google-calendar, camel-google-sheets and camel-google-mail has been upgraded from Google Java SDK v1 to v2 and to latest API revisions. The camel-google-drive and camel-google-sheets have some API methods changes, but the others are identical as before.

The component has been upgraded to use Apache HttpComponents v5 which has an impact on how the underlying client is configured. There are 4 different timeouts (connectionRequestTimeout, connectTimeout, soTimeout and responseTimeout) instead of initially 3 (connectionRequestTimeout, connectTimeout and socketTimeout) and the default value of some of them has changed so please refer to the documentation for more details.

Please note that the socketTimeout has been removed from the possible configuration parameters of HttpClient, use responseTimeout instead.

Finally, the option soTimeout along with any parameters included into SocketConfig, need to be prefixed by httpConnection., the rest of the parameters including those defined into HttpClientBuilder and RequestConfig still need to be prefixed by httpClient. like before.

The API in org.apache.camel.http.common.HttpBinding has changed slightly to be more reusable. The parseBody method now takes in HttpServletRequest as input parameter. And all HttpMessage has been changed to generic Message types.

The io.fabric8:kubernetes-client library has been upgraded and some deprecated API usage has been removed. Operations previously prefixed with replace are now prefixed with update.

For example replaceConfigMap is now updateConfigMap, replacePod is now updatePod etc. The corresponding constants in class KubernetesOperations are also renamed. REPLACE_CONFIGMAP_OPERATION is now UPDATE_CONFIGMAP_OPERATION, REPLACE_POD_OPERATION is now UPDATE_POD_OPERATION etc.

The following constants has been moved from BaseMainSupport / Main to MainConstants:

The metrics has been renamed to follow Micrometer naming convention .

The command camel dependencies has been renamed to camel dependency.

In Camel CLI the -dir parameter for init and run goal has been renamed to require 2 dashes --dir like all the other options.

The camel stop command will now by default stop all running integrations (the option --all has been removed).

The Placeholders substitutes is changed to use #name instead of $name syntax.

The camel-openapi-java component has been changed to use io.swagger.v3 libraries instead of io.apicurio.datamodels. As a result, the return type of the public method org.apache.camel.openapi.RestOpenApiReader.read() is now io.swagger.v3.oas.models.OpenAPI instead of io.apicurio.datamodels.openapi.models.OasDocument. When an OpenAPI 2.0 (swagger) specification is parsed, it is automatically upgraded to OpenAPI 3.0.x by the swagger parser. This version also supports OpenAPI 3.1.x specifications. The related spring-boot starter components have been modified to use the new return type.

Property names of blob fields on generated DTOs no longer have 'Url' affixed. For example, the ContentVersionUrl property is now ContentVersion.

The default delay (on slack consumer) is changed from 0.5s to 10s to avoid being rate limited to often by Slack.

The option replyTimeout in camel-spring-rabbitmq has been fixed and the default value from 5 to 30 seconds (this is the default used by Spring).

When declaring a restConfiguration in a Spring Beans XML file, for example:

<camelContext id="SampleCamel" xmlns="http://camel.apache.org/schema/spring">
    <restConfiguration port="8080" bindingMode="off" scheme="http"
                       contextPath="myapi" apiContextPath="myapi/swagger">
    </restConfiguration>

<camelContext id="SampleCamel" xmlns="http://camel.apache.org/schema/spring">
    <restConfiguration port="8080" bindingMode="off" scheme="http"
                       contextPath="myapi" apiContextPath="myapi/swagger">
    </restConfiguration>

The Camel Spring Boot application does not start due to a circular references error. The RestConfigurationDefinitionAutoConfiguration property is used when you use the Spring properties to configure the REST component. When you define the REST configuration in the XML file, the RestConfigurationDefinitionAutoConfiguration property is not needed. You can disable this property as follows:

@SpringBootApplication(exclude = RestConfigurationDefinitionAutoConfiguration.class)
// load the spring xml file from classpath
@ImportResource("classpath:my-camel.xml")
public class SampleCamelApplication {

@SpringBootApplication(exclude = RestConfigurationDefinitionAutoConfiguration.class)
// load the spring xml file from classpath
@ImportResource("classpath:my-camel.xml")
public class SampleCamelApplication {

Camel now shutdowns a bit later during Spring Boot shutdown. This allows Spring Boot graceful shutdown to complete first (stopping Spring Boot HTTP server gracefully), and then afterward Camel is doing its own Graceful Shutdown.

Technically camel-spring has changed getPhase() from returning Integer.MAX_VALUE to Integer.MAX_VALUE - 2049. This gives room for Spring Boot services to shut down first.

The uri tags are now static instead of dynamic (by default), as potential too many tags generated due to URI with dynamic values. This can be enabled again by setting camel.metrics.uriTagDynamic=true.

The platform-http-starter has been changed from using camel-servlet to use Spring HTTP server directly. Therefore, all the HTTP endpoints are no longer prefixed with the servlet context-path (default is camel).

For example:

from("platform-http:myservice")
  .to("...")

from("platform-http:myservice")
  .to("...")

Then calling myservice would before require to include the context-path, such as http://localhost:8080/camel/myservice. Now the context-path is not in use, and the endpoint can be called with http://localhost:8080/myservice.

If the route or consumer is suspended then http status 503 is now returned instead of 404.

The component was updated to use Twitter4j version 4.1.2, which has moved the packages used by a few of its classes. If accessing certain twitter-related data, such as the Twit status, you need to update the packages used from twitter4j.Status to twitter4j.v1.Status.