Working on macosx, I often find that things are easier than I thought - just drop something where it makes sense, or do what you would naturally do, and things work as expected. Often, at least.

I had the same experience today playing with OSGi services - one of my services needs to be informed of all configuration changes. OSGi provides a ConfigurationListener interface for that, but how are those registered with the framework?

That's actually much easier than I thought at first - here's the complete source code:

import org.osgi.service.cm.ConfigurationEvent; import org.osgi.service.cm.ConfigurationListener; import org.slf4j.Logger; import org.slf4j.LoggerFactory;

/** * @scr.component * immediate="true" * metatype="no" * @scr.service */ public class DebuggingConfigurationListener implements ConfigurationListener {

private final Logger log = LoggerFactory.getLogger(getClass());	

public void configurationEvent(ConfigurationEvent e) {
	log.info("Got ConfigurationEvent, pid={}, type={}", e.getPid(), e.getType());
}

}

Not bad hey? The scr.service annotation causes the class to be registered as a ConfigurationListener service, and the framework uses a whiteboard pattern to send configuration events to all such services.

Note to self: make things easier than what people expect.