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Available as of Camel 2.15.0

Info
Camel-scr bundle is not included in Apache Camel versions prior 2.15.0, but the artifact itself can be used with any Camel version since 2.12.0.

org.apache.camel/camel-scr bundle provides a base class, AbstractCamelRunner, which manages a Camel context for you and a helper class, ScrHelper, for using your SCR properties in unit tests. Camel-scr feature for Apache Karaf defines all features and bundles required for running Camel in SCR bundles.

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Code Block

language	java
title	Load routesImplement getRouteBuilders()

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

...

Code Block

language	java
title	Define Default configuration with in annotations

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

...

Code Block

language	java
title	CamelScrExampleRoute.java

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

import org.apache.camel.LoggingLevel;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.impl.SimpleRegistry;
import org.apache.commons.lang.Validate;

public class CamelScrExampleRoute extends RouteBuilder {

    SimpleRegistry registry;

    // Configured fields
    private String camelRouteId;
    private Integer maximumRedeliveries;
    private Long redeliveryDelay;
    private Double backOffMultiplier;
    private Long maximumRedeliveryDelay;

    public CamelScrExampleRoute(final SimpleRegistry registry) {
        this.registry = registry;
    }

    @Override
	public void configure() throws Exception {
        checkProperties();

        // Add a bean to Camel context registry
        registry.put("test", "bean");

        errorHandler(defaultErrorHandler()
            .retryAttemptedLogLevel(LoggingLevel.WARN)
            .maximumRedeliveries(maximumRedeliveries)
            .redeliveryDelay(redeliveryDelay)
            .backOffMultiplier(backOffMultiplier)
            .maximumRedeliveryDelay(maximumRedeliveryDelay));

        from("{{from}}")
            .startupOrder(2)
            .routeId(camelRouteId)
            .onCompletion()
                .to("direct:processCompletion")
            .end()
            .removeHeaders("CamelHttp*")
            .to("{{to}}");


		from("direct:processCompletion")
            .startupOrder(1)
            .routeId(camelRouteId + ".completion")
            .choice()
                .when(simple("${exception} == null"))
                    .log("{{messageOk}}")
                .otherwise()
                    .log(LoggingLevel.ERROR, "{{messageError}}")
            .end();
		}
	}

    public void checkProperties() {
        Validate.notNull(camelRouteId, "camelRouteId property is not set");
        Validate.notNull(maximumRedeliveries, "maximumRedeliveries property is not set");
        Validate.notNull(redeliveryDelay, "redeliveryDelay property is not set");
        Validate.notNull(backOffMultiplier, "backOffMultiplier property is not set");
        Validate.notNull(maximumRedeliveryDelay, "maximumRedeliveryDelay property is not set");
    }
}

Let's take a look at CamelScrExampleRoute in more detail.

Code Block
// Configured fields private String camelRouteId; private Integer maximumRedeliveries; private Long redeliveryDelay; private Double backOffMultiplier; private Long maximumRedeliveryDelay;

...

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:

Done!

Now run:

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/

Unit testing Camel routes

Service Component is a POJO and has no special requirements for (non-OSGi) unit testing. There are however some techniques that are specific to Camel SCR or just make testing easier.

Below is an example unit test, generated by camel-archetype-scr:

mvn install

and the bundle is ready to be deployed.

Unit testing Camel routes

Service Component is a POJO and has no special requirements for (non-OSGi) unit testing. There are however some techniques that are specific to Camel SCR or just make testing easier.

Below is an example unit test, generated by camel-archetype-scr:

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

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
Disable JMX for test
      public void setUpcontext.disableJMX();

 throws Exception {
     // Fake  log.info("*******************************************************************");a component for test
        logcontext.infoaddComponent("Test: amq", +new testName.getMethodNameMockComponent());
    }

      log.info("*******************************************************************");

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

	@Test
	public void testRoutes() throws Exception {
        // Set property prefix for unit testing
Adjust routes
        List<RouteDefinition> routes = Systemcontext.setProperty(CamelScrExample.PROPERTY_PREFIX, "unit"getRouteDefinitions();

        // Prepare the integrationroutes.get(0).adviceWith(context, new AdviceWithRouteBuilder() {
        integration  = new CamelScrExample();
@Override
             integration.prepare(null, ScrHelper.getScrProperties(integration.getClass().getName()));
public void configure() throws Exception {
         context  = integration.getContext();

    // Replace "from" endpoint with  // Disable JMX for test
direct:start
                context.disableJMX(replaceFromWith("direct:start");

        // Fake a component for test
   // Mock and skip  context.addComponent("amq", new MockComponent());
result endpoint
      }

    @After
    public void tearDownmockEndpoints() throws Exception {"log:*");
        integration.stop();
    }

	@Test
	public void testRoutes() throws Exception {
        // Adjust routes});

        List<RouteDefinition>MockEndpoint routesresultEndpoint = context.getRouteDefinitions(getEndpoint("mock:log:foo", MockEndpoint.class);

        routes.get(0).adviceWith(context, new AdviceWithRouteBuilder() {
       // resultEndpoint.expectedMessageCount(1); // If you want to just check the number of messages
     @Override
   resultEndpoint.expectedBodiesReceived("hello"); // If you want to check the  public void configure() throws Exception {contents

        // Start the integration
        integration.run();

        // ReplaceSend "from"the endpointtest with direct:start
message
                 replaceFromWithcontext.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

        // MockSet property andprefix skipfor resultunit endpointtesting
        System.setProperty(CamelScrExample.PROPERTY_PREFIX, "unit");

This allows you to override parts of the configuration by prefixing properties with "unit.". For example, unit.from overrides from for the unit test.

Prefixes can be used to handle 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

       mockEndpoints("log:*");
     // 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

});

        MockEndpoint// resultEndpointAdjust = context.getEndpoint("mock:log:foo", MockEndpoint.class);
routes
        List<RouteDefinition> routes //= resultEndpointcontext.expectedMessageCountgetRouteDefinitions(1);

 // If you want to just check the number of messages routes.get(0).adviceWith(context, new AdviceWithRouteBuilder() {
        resultEndpoint.expectedBodiesReceived("hello"); // If you want@Override
 to check the contents

        //public Startvoid the integration
  configure() throws Exception {
      integration.run();

          // Send the test messageReplace "from" endpoint with direct:start
        context.createProducerTemplate().sendBody        replaceFromWith("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
 Mock and skip result endpoint
                System.setProperty(CamelScrExample.PROPERTY_PREFIX, "unit");

This allows you to override parts of the configuration by prefixing properties with "unit.". For example, unit.from overrides from for the unit test.

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.

mockEndpoints("log:*");
            }
        });

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

Code Block

language	java
title	Getting test configuration from annotations	Starting the routes

        // Start the integration
        integration.prepare(null, ScrHelper.getScrProperties(integration.getClass().getNamerun()));

Here we configure start the Service Component in test and along with the same properties that would be used in OSGi environmentit the routes.

Code Block

language	java
title	Mocking components for Sending a test message

        // FakeSend athe componenttest for testmessage
        context.createProducerTemplate().addComponentsendBody("amqdirect:start", new MockComponent()"hello");

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

Here we send a message to a route in test.

Running the bundle in Apache Karaf

Once the bundle has been built with mvn install it's ready to be deployed. To deploy the bundle on Apache Karaf perform the following steps on Karaf command line:

Code Block

language	javatext
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");

Here we send a message to a route in test.

Using Camel SCR bundle as a template

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Deploying the bundle in Apache Karaf

# Add Camel feature repository
karaf@root> features:chooseurl camel 2.15-SNAPSHOT
 
# Install camel-scr feature
karaf@root> features:install camel-scr
 
# Install commons-lang, used in the example route to validate parameters
karaf@root> osgi:install mvn:commons-lang/commons-lang/2.6
 
# Install and start your bundle
karaf@root> osgi:install -s mvn:example/camel-scr-example/1.0-SNAPSHOT
 
# See how it's running
karaf@root> log:tail -n 10
 
Press ctrl-c to stop watching the log.

Overriding the default configuration

By default, Service Component's configuration PID equals the fully qualified name of its class. You can change the example bundle's properties with Karaf's config:* commands:

Code Block

language	text
title	Override a property

# Override 'messageOk' property
karaf@root> config:propset -p example.CamelScrExample messageOk "This is better logging"

Or you can change the configuration by editing property files in Karaf's etc folder.

Using Camel SCR bundle as a template

Let's say you have a Camel SCR bundle that implements an integration pattern that you use frequently, say, from → to, with success/failure logging and redelivery which also happens to be the pattern our example route implements. You probably don't want to create a separate bundle for every instance. No worries, SCR has you covered.

Create a configuration PID for your Service Component, but add a tail with a dash and SCR will use that configuration to create a new instance of your component.

Code Block

language	text
title	Creating a new Service Component instance

# Create a PID with a tail
karaf@root> config:edit example.CamelScrExample-anotherone
 
# Override some properties
karaf@root> config:propset camelContextId my-other-context
karaf@root> config:propset to "file://removeme?fileName=removemetoo.txt"
 
# Save the PID
karaf@root> config:update

This will start a new CamelContext with your overridden properties. How convenient.

Tip

When designing a Service Component to be a template you typically don't want it to start without a "tailed" configuration i.e. with the default configuration.

To prevent your Service Component from starting with the default configuration add policy = ConfigurationPolicy.REQUIRE to the class level @Component annotation.

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Versions Compared

Old Version 11

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Key

Unit testing Camel routes

Unit testing Camel routes

Running the bundle in Apache Karaf

Using Camel SCR bundle as a template

Overriding the default configuration

Using Camel SCR bundle as a template