Apache Camel 4.x Upgrade Guide

Added void bind(String id, Class<?> type, Object bean, String initMethod, String destroyMethod) method to org.apache.camel.spi.Registry to support init and destroy method on beans.

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 tracer (BacklogTracer) has changed the backlogSize default value from 1000 to 100, and maxBodySize from 128kb to 32kb. This reduces the amount of data captured and stored and helps reduce the tracing overhead.

The org.apache.camel.support.DefaultExchangeHolder will now include both exchange variables and properties, if the parameter includeProperties is set to true.

The camel trace command has changed to show tracing status (by default). To dump traced messages use camel trace --action=dump.

The following components that were marked as deprecated:

The header prefixes have 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).

The chat-with-tools feature was deprecated. Use the new camel-langchain4j-tool component.

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.