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h2. NMR Component

The *nmr* component is an adapter to the Normalized Message Router (NMR) in [ServiceMix|http://servicemix.apache.org/home.html], which is intended for use by Camel applications deployed directly into the OSGi container. You can exchange objects with NMR and not only XML like this is the case with the JBI specification. The interest of this component is that you can interconnect camel routes deployed in different OSGI bundles. 

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

h3. Installing

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

{code}
features install nmr
{code}

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:

{code:xml}
<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>
{code}

h3. NMR consumer and producer endpoints

The following code:

{code}
from("nmr:MyServiceEndpoint")
{code}

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:

{code}
to("nmr:MyServiceEndpoint")
{code}

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

{anchor:URI-format}
h3. URI format

{code}
nmr:endpointName
{code}

h4. URI Options
{div:class=confluenceTableSmall}
|| Option || Default Value || Description ||
| {{runAsSubject}} | {{false}} | *Apache ServiceMix 4.4:* When this is set to *{{true}}* on a consumer endpoint, the endpoint will be invoked on behalf of the {{Subject}} that is set on the {{Exchange}} (i.e. the call to {{Subject.getSubject(AccessControlContext)}} will return the {{Subject}} instance) |
| {{synchronous}} | {{false}} | When this is set to *{{true}}* on a consumer endpoint, an incoming, synchronous NMR Exchange will be handled on the sender's thread instead of being handled on a new thread of the NMR endpoint's thread pool |
| {{timeout}} | {{0}} | *Apache ServiceMix 4.4:* When this is set to a value greater than 0, the producer endpoint will timeout if it doesn't receive a response from the NMR within the given timeout period (in milliseconds).  Configuring a timeout value will switch to using synchronous interactions with the NMR instead of the usual asynchronous messaging. |
{div}

h4. Examples

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

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

h3. Using Stream bodies
If you are using a stream type as the message body, you should be aware that a stream is only capable of being read 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.

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

From *Camel 1.5* onwards, the stream caching is default enabled, so it is not necessary to set the {{streamCaching()}} option.
In *Camel 2.0* we store big input streams (by default, over 64K) in a {{temp}} file using {{CachedOutputStream}}. When you close the input stream, the temp file will be deleted.

h4. Testing
NMR camel routes can be tested using the camel unit test approach even if they will be deployed next in different bundles on an OSGI runtime. With this aim in view, you will extend the ServiceMixNMR Mock class {{org.apache.servicemix.camel.nmr.AbstractComponentClassAbstractComponentTest}} which will create a NMR bus, register the Camel NMR Component and the endpoints defined into the Camel routes.

{code}
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 {
        return new RouteBuilder() {

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


{include:Endpoint See Also}