• Using the NMR
  • Camel NMR
  • Event Listeners

Event listeners

The NMR has a rich event API that can be used to receive all sort of notifications about what's happening in the NMR.
Currently, two types of listeners are defined:

• org.apache.servicemix.nmr.api.event.EndpointListener

• org.apache.servicemix.nmr.api.event.ExchangeListener

Endpoint Listener

API

The EndpointListener defined two methods:

• endpointRegistered is called whenever a new endpoint is registered with the NMR

• endpointUnregistered is called whenever an existing endpoint is unregistered

public interface EndpointListener {
    void endpointRegistered(InternalEndpoint endpoint);
    void endpointUnregistered(InternalEndpoint endpoint);
}

Registering EndpointListener

An EndpointListener can be registered directly with the NMR:

nmr.getListenerRegistry().register(listener, null);

The recommended way of registering an EndpointListener is by adding it to the OSGi Service Registry, e.g. using a Blueprint XML file:

<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
           xmlns:ext="http://aries.apache.org/blueprint/xmlns/blueprint-ext/v1.0.0">

    <bean id="myListener" class="..."/>

    <service ref="myListener">
      <interfaces>
        <value>org.apache.servicemix.nmr.api.event.EndpointListener</value>
        <value>org.apache.servicemix.nmr.api.event.Listener</value>
      </interfaces>
    </service>

</blueprint>

Example

An example of using an endpoint listener is shipped as part of the ServiceMix distribution. It can be found in the examples/interceptors/endpoint directory.

ExchangeListener

API

The ExchangeListener defined two methods:

• exchangeSent is called whenever an exchange is sent to the NMR for delivery

• exchangeDelivered is called whenever an exchange is being delivered to an endpoint

• exchangeFailed is called when a failure occurs while handling an exchange

public interface ExchangeListener {
    void exchangeSent(Exchange exchange);
    void exchangeDelivered(Exchange exchange);
    void exchangeFailed(Exchange exchange);
}

Registering ExchangeListener

An ExchangeListener can be registered directly with the NMR:

nmr.getListenerRegistry().register(listener, null);

The recommended way of registering an ExchangeListener is by adding it to the OSGi Service Registry, e.g. using a Blueprint XML file:

<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
           xmlns:ext="http://aries.apache.org/blueprint/xmlns/blueprint-ext/v1.0.0">

    <bean id="myListener" class="..."/>

    <service ref="myListener">
      <interfaces>
        <value>org.apache.servicemix.nmr.api.event.ExchangeListener</value>
        <value>org.apache.servicemix.nmr.api.event.Listener</value>
      </interfaces>
    </service>

</blueprint>

Example

An example of using an exchange listener is shipped as part of the ServiceMix distribution. It can be found in the examples/interceptors/exchange directory.