Service Monitoring - OSGI

There are 2 approaches for doing this.


1. Class implementing Service Listener gets all service lifecycle Events .

public class PGServiceListener implements ServiceListener, BundleActivator {
……..

@Override
public void start(BundleContext cntxt) throws Exception {
cntxt.addServiceListener(this);

}

@Override
public void stop(BundleContext cntxt) throws Exception {
// TODO Auto-generated method stub

}

public void serviceChanged(ServiceEvent event) {
-à this is called for every service life cycle event
}


}

Here this class will be mentioned in the manifest file as a bundle Activator

2. Listening to the market Interface . Assuming that all the services implement a interface IService we can have the following listener which get all service related events.

<osgi:list id="listService"

interface="com.partygaming.service.monitor.external.IService"

cardinality="0..N">

<osgi:listener ref="serviceListener1" bind-method="bindService"

unbind-method="unBindService"></osgi:listener>

</osgi:list>



Looks like the second approach is better, as we get only 2 events, service register and unregister which we are interested in .It also gives all the properties of the service which will help us maintain other info like version.