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AbstractCamelRunner class ties CamelContext's lifecycle to Service Component's lifecycle and handles configuration with help of Camel's PropertiesComponent. All you have to do to make a Service Component out of your java class is to extend it from AbstractCamelRunner and add the following org.apache.felix.scr.annotations on class level:

Code Block

language	java
title	Add required annotations

@Component
@References({
    @Reference(name = "camelComponent",referenceInterface = ComponentResolver.class,
        cardinality = ReferenceCardinality.MANDATORY_MULTIPLE, policy = ReferencePolicy.DYNAMIC,
        policyOption = ReferencePolicyOption.GREEDY, bind = "gotCamelComponent", unbind = "lostCamelComponent")
})

Then implement getRouteBuilders() method which returns the Camel routes you want to run:

Code Block

language	java
title	Load routes

	@Override
    protected List<RoutesBuilder> getRouteBuilders() {
        List<RoutesBuilder> routesBuilders = new ArrayList<>();
        routesBuilders.add(new YourRouteBuilderHere(registry));
        routesBuilders.add(new AnotherRouteBuilderHere(registry));
        return routesBuilders;
    }

And finally provide the default configuration with:

Code Block

language	java
title	Define configuration with annotations

@Properties({
   @Property(name = "camelContextId", value = "my-test"),
   @Property(name = "active", value = "true"),
   @Property(name = "...", value = "..."),
   ...
})

That's all. And if you used camel-archetype-scr to generate a project all this is already taken care of.

Below is an example of a complete Service Component class, generated by camel-archetype-scr:

Code Block

language	java
title	CamelScrExample.java

// This file was generated from org.apache.camel.archetypes/camel-archetype-scr/2.15-SNAPSHOT
package example;

import java.util.ArrayList;
import java.util.List;

import org.apache.camel.scr.AbstractCamelRunner;
import example.internal.CamelScrExampleRoute;
import org.apache.camel.RoutesBuilder;
import org.apache.camel.spi.ComponentResolver;
import org.apache.felix.scr.annotations.*;

@Component(label = CamelScrExample.COMPONENT_LABEL, description = CamelScrExample.COMPONENT_DESCRIPTION, immediate = true, metatype = true)
@Properties({
    @Property(name = "camelContextId", value = "camel-scr-example"),
    @Property(name = "camelRouteId", value = "foo/timer-log"),
    @Property(name = "active", value = "true"),
    @Property(name = "from", value = "timer:foo?period=5000"),
    @Property(name = "to", value = "log:foo?showHeaders=true"),
    @Property(name = "messageOk", value = "Success: {{from}} -> {{to}}"),
    @Property(name = "messageError", value = "Failure: {{from}} -> {{to}}"),
    @Property(name = "maximumRedeliveries", value = "0"),
    @Property(name = "redeliveryDelay", value = "5000"),
    @Property(name = "backOffMultiplier", value = "2"),
    @Property(name = "maximumRedeliveryDelay", value = "60000")
})
@References({
    @Reference(name = "camelComponent",referenceInterface = ComponentResolver.class,
        cardinality = ReferenceCardinality.MANDATORY_MULTIPLE, policy = ReferencePolicy.DYNAMIC,
        policyOption = ReferencePolicyOption.GREEDY, bind = "gotCamelComponent", unbind = "lostCamelComponent")
})
public class CamelScrExample extends AbstractCamelRunner {

    public static final String COMPONENT_LABEL = "example.CamelScrExample";
    public static final String COMPONENT_DESCRIPTION = "This is the description for camel-scr-example.";

    @Override
    protected List<RoutesBuilder> getRouteBuilders() {
        List<RoutesBuilder> routesBuilders = new ArrayList<>();
        routesBuilders.add(new CamelScrExampleRoute(registry));
        return routesBuilders;
    }
}

CamelContextId and active properties control the CamelContext's name (defaults to "camel-runner-default") and whether it will be started or not (defaults to "false"), respectively. In addition to these you can add and use as many properties as you like. Camel's PropertiesComponent handles recursive properties and prefixing with fallback without problem.

...

You can generate a project with the following steps:

Code Block

language	text
title	Generating a project

$ mvn archetype:generate -Dfilter=org.apache.camel.archetypes:camel-archetype-scr
 
Choose archetype:
1: local -> org.apache.camel.archetypes:camel-archetype-scr (Creates a new Camel SCR bundle project for Karaf)
Choose a number or apply filter (format: [groupId:]artifactId, case sensitive contains): : 1
Define value for property 'groupId': : example
[INFO] Using property: groupId = example
Define value for property 'artifactId': : camel-scr-example
Define value for property 'version': 1.0-SNAPSHOT: :
Define value for property 'package': example: :
[INFO] Using property: archetypeArtifactId = camel-archetype-scr
[INFO] Using property: archetypeGroupId = org.apache.camel.archetypes
[INFO] Using property: archetypeVersion = 2.15-SNAPSHOT
Define value for property 'className': : CamelScrExample
Confirm properties configuration:
groupId: example
artifactId: camel-scr-example
version: 1.0-SNAPSHOT
package: example
archetypeArtifactId: camel-archetype-scr
archetypeGroupId: org.apache.camel.archetypes
archetypeVersion: 2.15-SNAPSHOT
className: CamelScrExample
Y: :

All done! See ReadMe.txt in the generated project folder for the next steps:

Code Block

language	text
title	ReadMe.txt

Camel SCR bundle project
========================

To build this project run

    mvn install

To deploy this project in Apache Karaf (2.4.0)

    On Karaf command line:

    # Add Camel feature repository
    features:chooseurl camel 2.15-SNAPSHOT

    # Install camel-scr feature
    features:install camel-scr

    # Install commons-lang, used in the example route to validate parameters
    osgi:install mvn:commons-lang/commons-lang/2.6

    # Install and start your bundle
    osgi:install -s mvn:example/camel-scr-example/1.0-SNAPSHOT

    # See how it's running
    log:tail -n 10

    Press ctrl-c to stop watching the log.

For more help see the Apache Camel documentation

    http://camel.apache.org/

...

Code Block

language	java
title	CamelScrExampleTest.java

// This file was generated from org.apache.camel.archetypes/camel-archetype-scr/2.15-SNAPSHOT
package example;

import java.util.List;

import org.apache.camel.scr.internal.ScrHelper;
import org.apache.camel.builder.AdviceWithRouteBuilder;
import org.apache.camel.component.mock.MockComponent;
import org.apache.camel.component.mock.MockEndpoint;
import org.apache.camel.model.ModelCamelContext;
import org.apache.camel.model.RouteDefinition;
import org.junit.After;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TestName;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

@RunWith(JUnit4.class)
public class CamelScrExampleTest {

    Logger log = LoggerFactory.getLogger(getClass());

    @Rule
    public TestName testName = new TestName();

    CamelScrExample integration;
    ModelCamelContext context;

    @Before
    public void setUp() throws Exception {
        log.info("*******************************************************************");
        log.info("Test: " + testName.getMethodName());
        log.info("*******************************************************************");

        // Set property prefix for unit testing
        System.setProperty(CamelScrExample.PROPERTY_PREFIX, "unit");

        // Prepare the integration
        integration = new CamelScrExample();
        integration.prepare(null, ScrHelper.getScrProperties(integration.getClass().getName()));
        context = integration.getContext();

        // Disable JMX for test
        context.disableJMX();

        // Fake a component for test
        context.addComponent("amq", new MockComponent());
    }

    @After
    public void tearDown() throws Exception {
        integration.stop();
    }

	@Test
	public void testRoutes() throws Exception {
        // Adjust routes
        List<RouteDefinition> routes = context.getRouteDefinitions();

        routes.get(0).adviceWith(context, new AdviceWithRouteBuilder() {
            @Override
            public void configure() throws Exception {
                // Replace "from" endpoint with direct:start
                replaceFromWith("direct:start");
                // Mock and skip result endpoint
                mockEndpoints("log:*");
            }
        });

        MockEndpoint resultEndpoint = context.getEndpoint("mock:log:foo", MockEndpoint.class);
        // resultEndpoint.expectedMessageCount(1); // If you want to just check the number of messages
        resultEndpoint.expectedBodiesReceived("hello"); // If you want to check the contents

        // Start the integration
        integration.run();

        // Send the test message
        context.createProducerTemplate().sendBody("direct:start", "hello");

        resultEndpoint.assertIsSatisfied();
	}
}

Now, let's take a look at the interesting bits one by one.

Code Block

title	Using property prefixing

        // Set property prefix for unit testing
        System.setProperty(CamelScrExample.PROPERTY_PREFIX, "unit");

...

Prefixes, as a whole, can be used to cover the differences between the runtime environments where your routes might run. Moving the unchanged bundle through development, testing and production environments is a typical use case.

Code Block

language	java
title	Getting test configuration from annotations

        integration.prepare(null, ScrHelper.getScrProperties(integration.getClass().getName()));

Here we configure the Service Component in test with the same properties that would be used in OSGi environment.

Code Block

language	java
title	Mocking components for test

        // Fake a component for test
        context.addComponent("amq", new MockComponent());

Components that are not available in test can be mocked like this to allow the route to start.

Code Block

language	java
title	Adjusting routes for test

        // Adjust routes
        List<RouteDefinition> routes = context.getRouteDefinitions();

        routes.get(0).adviceWith(context, new AdviceWithRouteBuilder() {
            @Override
            public void configure() throws Exception {
                // Replace "from" endpoint with direct:start
                replaceFromWith("direct:start");
                // Mock and skip result endpoint
                mockEndpoints("log:*");
            }
        });

Camel's AdviceWith feature allows routes to be modified for test.

Code Block

language	java
title	Starting the routes

        // Start the integration
        integration.run();

Here we start the Service Component and along with it the routes.

Code Block

language	java
title	Sending a test message

        // Send the test message
        context.createProducerTemplate().sendBody("direct:start", "hello");

...

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