NMR

NMR Component

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

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:

features install nmr

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>

NMR consumer and producer endpoints

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 JBI endpoint.

URI format

nmr:endpointName

URI Options

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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.

Examples

from("nmr:MyServiceEndpoint")
from("nmr:MyServiceEndpoint?synchronous=true").to("nmr:AnotherEndpoint")

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.

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

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.

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