Why is Camel sending Message body content rather than the Message itself when using the Bean component?

Question

I created a Java class for EIP Event Messages. I expected to receive a Message at Observer.accept(Object o) when using Camel's Bean component but I get an Event instead. While this is convenient since I don't have to extract the Event from the Message's body myself I don't have access to the message's possible headers and attachments with this.

EventMessageTest.java

package name.igb.eip.integration.styles.test;

import java.time.Instant;
import java.util.List;
import java.util.Vector;
import java.util.function.Consumer;
import java.util.function.Supplier;

import org.apache.camel.CamelContext;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.impl.DefaultCamelContext;
import org.apache.camel.impl.engine.DefaultCamelContextNameStrategy;
import org.apache.camel.model.RouteDefinition;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

class EventMessageTest {

    static final Logger log = LoggerFactory.getLogger( EventMessageTest.class );

    public static void main( final String... args ) throws Exception {

        try ( CamelContext cc = new DefaultCamelContext(); ) {

            cc.setNameStrategy( new DefaultCamelContextNameStrategy( "Messaging Sample" ) );

            cc.getRegistry().bind( "Subject", new Subject( "Subject" ) );
            cc.getRegistry().bind( "Observer", new Observer( "Observer" ) );

            final List observers = new Vector<>();
            observers.add( new Observer( "Observer 1" ) );
            observers.add( new Observer( "Observer 2" ) );
            observers.add( new Observer( "Observer 3" ) );

            cc.addRoutes( new RouteBuilder() {

                @Override
                public void configure() {
                    final RouteDefinition route =
                        from( "timer:Event?repeatCount=1" )
                            .log( "creating endpoint " + Subject.class.getSimpleName() + "..." )
                            .bean( Subject.class ) // Subject.get() returns an Event
                            .log( "creating..." )
                            .process().message( m -> {
                                log.info( "...{}<{}>",
                                    m, m.getBody( Event.class ).getClass().getSimpleName() );
                            } )
                            .routeId( "Event route" );

                    for ( final Observer observer : observers ) {
                        log.info( "creating endpoint {}...", observer.id );
                        route
                            .to( "bean:Observer" ) // this sends Event to Observer
                            // this alternative sends Message to Observer N
                            .process().message( m -> {
                                observer.accept( m );
                            } );
                    }
                }
            } ); // addRoutes( RouteBuilder() )

            cc.start();
            Thread.sleep( 2000 );
            cc.stop();
            cc.close();
        }
        catch ( final Exception e ) {
            e.printStackTrace();
        }
    } // main()

} // EventMessageTest

class Subject implements Supplier {

    String id;

    Subject( final String id ) {
        this.id = id;
    }

    @Override
    @Handler
    public Event get() {
        return new Event();
    }

} // Subject

class Event {
    String id = Instant.now().toString();
} // Event

class Observer implements Consumer

Why is Camel sending Message body content rather than the Message itself when using the Bean component?

EventMessageTest.java

Output

POM (for MRE testing)

Answers (0)

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