Apache Camel 4.x Upgrade Guide

The UseOriginalAggregationStrategy class will now propagate the caught exception stored in the exchange property Exchange.EXCEPTION_CAUGHT as well. For example when using the Splitter EIP with this, then any caught exception during splitting, would be stored as well, which allows access to this information afterward, for example in an onCompletion where the caught exception can be used to know some error happened during splitting.

Internally, Camel will now use Java’s own InputStream.transferTo for copying data between streams whenever such copies don’t require customized buffer sizes or data flushing policies. Additionally, the size of the data buffer used by Camel when performing these copies has increased from 4096 bytes to 16384 bytes (the default buffer size used by Java 21).

The following components that were marked as deprecated:

The header prefixes has been corrected from CamelAS2. → CamelAs2. to be consistent with naming convention used by other API based components. The documentation uses the correct naming prefix as CamelAs2..

The KafkaIdempotentRepository will now continue to sync cache updates after Camel has been started. You can configure startupOnly=true to only sync the cache once on startup (however then the cache is not synced with other Camel nodes in a cluster).

Continuing the multi-release tests cleanups, on this one, restricted methods from the CamelTestSupport class have been marked as final and cannot be extended.

We stopped relying on com.sun.xml.bind:jaxb-impl in favor of org.glassfish.jaxb:jaxb-runtime. This change should have no impact on existing code, because recent versions of the two artifacts bring the same classes. The main motivation for this change is to allow projects that still require classes from javax.xml.bind package to be able to depend on pre-3.x versions of com.sun.xml.bind:jaxb-impl together with the recent version of org.glassfish.jaxb:jaxb-runtime brought by Camel.