DeadLetterChannelOnRedeliveryTest.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.camel.processor;

import org.apache.camel.ContextTestSupport;
import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.component.mock.MockEndpoint;

/**
 * Unit test for testing possibility to modify exchange before redelivering
 */
public class DeadLetterChannelOnRedeliveryTest extends ContextTestSupport {

    static int counter;

    public void testOnExceptionAlterMessageBeforeRedelivery() throws Exception {
        MockEndpoint mock = getMockEndpoint("mock:result");
        mock.expectedBodiesReceived("Hello World3");

        template.sendBody("direct:start", "Hello World");

        assertMockEndpointsSatisfied();
    }

    public void testOnExceptionAlterMessageWithHeadersBeforeRedelivery() throws Exception {
        MockEndpoint mock = getMockEndpoint("mock:result");
        mock.expectedBodiesReceived("Hello World3");
        mock.expectedHeaderReceived("foo", "123");

        template.sendBodyAndHeader("direct:start", "Hello World", "foo", "123");

        assertMockEndpointsSatisfied();
    }

    @Override
    protected void setUp() throws Exception {
        super.setUp();
        counter = 0;
    }

    @Override
    protected RouteBuilder createRouteBuilder() throws Exception {
        return new RouteBuilder() {
            @Override
            public void configure() throws Exception {
                // START SNIPPET: e1
                // we configure our Dead Letter Channel to invoke
                // MyRedeliveryProcessor before a redelivery is
                // attempted. This allows us to alter the message before
                errorHandler(deadLetterChannel("mock:error").maximumRedeliveries(5)
                        .onRedelivery(new MyRedeliverProcessor())
                        // setting delay to zero is just to make unit testing faster
                        .redeliveryDelay(0L));
                // END SNIPPET: e1


                from("direct:start").process(new Processor() {
                    public void process(Exchange exchange) throws Exception {
                        // force some error so Camel will do redelivery
                        if (++counter <= 3) {
                            throw new IllegalArgumentException("Forced by unit test");
                        }
                    }
                }).to("mock:result");

            }
        };
    }

    // START SNIPPET: e2
    // This is our processor that is executed before every redelivery attempt
    // here we can do what we want in the java code, such as altering the message
    public class MyRedeliverProcessor implements Processor {

        public void process(Exchange exchange) throws Exception {
            // the message is being redelivered so we can alter it

            // we just append the redelivery counter to the body
            // you can of course do all kind of stuff instead
            String body = exchange.getIn().getBody(String.class);
            int count = exchange.getIn().getHeader(Exchange.REDELIVERY_COUNTER, Integer.class);

            exchange.getIn().setBody(body + count);

            // the maximum redelivery was set to 5
            int max = exchange.getIn().getHeader(Exchange.REDELIVERY_MAX_COUNTER, Integer.class);
            assertEquals(5, max);
        }
    }
    // END SNIPPET: e2


}