NMR

The nmr component is an adapter to the Normalized Message Router (NMR) in ServiceMix, which is intended for use by Apache Camel applications deployed directly into the OSGi container. By contrast, the JBI component is intended for use by Apache Camel applications deployed into the ServiceMix JBI container.

By contrast, the JBI component is intended for use by Camel applications deployed into the ServiceMix JBI container.

The NMR component is provided with Apache ServiceMix. It is not distributed with Apache Camel. To install the NMR component in ServiceMix, enter the following command in the ServiceMix console window:

features install nmr

In plain Karaf the nmr component can also be installed using the servicemix artifacts:

features:chooseurl camel <version>
features:addurl mvn:org.apache.servicemix.nmr/apache-servicemix-nmr/1.5.0/xml/features
features:install camel-blueprint nmr camel-nmr
install -s mvn:org.apache.servicemix.camel/org.apache.servicemix.camel.component/4.4.2

You also need to instantiate the NMR component. You can do this by editing your Spring configuration file, META-INF/spring/*.xml, and adding the following bean instance:

<beans xmlns:osgi="http://www.springframework.org/schema/osgi" ... >
    ...
    <bean id="nmr" class="org.apache.servicemix.camel.nmr.ServiceMixComponent">
        <property name="nmr">
            <osgi:reference interface="org.apache.servicemix.nmr.api.NMR" />
        </property>
    </bean>
    ...
</beans>

The following code:

from("nmr:MyServiceEndpoint")

Automatically exposes a new endpoint to the bus with endpoint name MyServiceEndpoint (see URI format).

When an NMR endpoint appears at the end of a route, for example:

to("nmr:MyServiceEndpoint")

the messages sent by this producer endpoint are sent to the already deployed NMR endpoint.

An NMR endpoint has this format:

nmr:endpointName

An NMR endpoint supports these options:

Consumer:

// consume nmr exchanges asynchronously
from("nmr:MyServiceEndpoint") 
// consume nmr exchanges synchronously and use the same thread as  defined by NMR ThreadPool
from("nmr:MyServiceEndpoint?synchronous=true").to()  

Producer:

// produce nmr exchanges asynchronously
from()...to("nmr:MyServiceEndpoint") 
// produce nmr exchanges synchronously and wait till 10s to receive response
from()...to("nmr:MyServiceEndpoint?timeout=10000") 

If you are using a stream type as the message body, be aware that a stream is capable of being read only once. So if you enable DEBUG logging, the body is usually logged and thus read. To deal with this, Camel has a streamCaching option that can cache the stream, enabling you to read it multiple times.

from("nmr:MyEndpoint").streamCaching().to("xslt:transform.xsl", "bean:doSomething");

From Apache Camel 1.5 onwards, stream caching is enabled by default, so you need not set the streamCaching() option. In Apache Camel 2.0 big input streams (by default, over 64K) are stored in a temp file, using CachedOutputStream. When you close the input stream, the temp file is deleted.

NMR camel routes can be tested using the Apache Camel unit test approach, even if they will be deployed next in different bundles in an OSGi runtime. With this aim in view, you will extend the ServiceMixNMR Mock class, org.apache.servicemix.camel.nmr.AbstractComponentTest, which will create an NMR bus, register the Apache Camel NMR Component and the endpoints defined into the Apache Camel routes.

public class ExchangeUsingNMRTest extends AbstractComponentTest {

    @Test
    public void testProcessing() throws InterruptedException {
        MockEndpoint mock = getMockEndpoint("mock:simple");
        mock.expectedBodiesReceived("Simple message body");

        template.sendBody("direct:simple", "Simple message body");

        assertMockEndpointsSatisfied();

    }

    @Override
    protected RouteBuilder createRouteBuilder() throws Exception {
        returnnew RouteBuilder() {

            @Override
            public void configure() throws Exception {
                from("direct:simple").to("nmr:simple");
                from("nmr:simple?synchronous=true").to("mock:simple");
            }
        };
    }
}