juneau-doc/docs/Topics/11.juneau-microservice-core/10.Listeners.html

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{8.0.0-new, 8.1.2-deprecated} 
Listeners

<p>
	As mentioned previously, the lifecycle methods for the {@link oaj.microservice.Microservice} class are explicitly
	defined as non-final so that they can be overridden by subclasses.
</p>
<p>
	In addition to this support, an interface for defining event listeners for your microservice:
</p>
<ul class='javatree'>
	<li class='jc'>{@link oaj.microservice.MicroserviceBuilder}
	<ul>
		<li class='jm'>{@link oaj.microservice.MicroserviceBuilder#listener(MicroserviceListener) listener(MicroserviceListener)} 
	</ul>
	<li class='jic'>{@link oaj.microservice.MicroserviceListener}
	<ul>
		<li class='jm'>{@link oaj.microservice.MicroserviceListener#onStart(Microservice) onStart(Microservice)} 
		<li class='jm'>{@link oaj.microservice.MicroserviceListener#onStop(Microservice) onStop(Microservice)} 
		<li class='jm'>{@link oaj.microservice.MicroserviceListener#onConfigChange(Microservice,ConfigEvents) onConfigChange(Microservice,ConfigEvents)} 
	</ul>
	<li class='jac'>{@link oaj.microservice.BasicMicroserviceListener}
</ul>
<p>
	This listener API can be used for listening for and reacting to configuration changes on the file system.
</p>
<p class='bpcode w800'>
	<jk>public class</jk> MyMicroserviceListener <jk>extends</jk> BasicMicroserviceListener {
	
		<ja>@Override</ja> <jc>/* MicroserviceListener */</jc>
		<jk>public void</jk> onConfigChange(Microservice microservice, ConfigEvents events) {
			
			<jc>// Restart the microservice if anything was modified in one of our sections</jc>
			<jk>if</jk> (events.isSectionChanged(<js>"MySection"</js>))
				microservice.stop().start();
		}
	}
</p>
<p>
	Note that the {@link oaj.microservice.Microservice#onConfigChange(ConfigEvents)} method can also be overridden
	to react to configuration changes as well:
</p>
<p class='bpcode w800'>
	<jk>public class</jk> MyMicroservice <jk>extends</jk> Microservice {
	
		<ja>@Override</ja> <jc>/* MicroserviceListener */</jc>
		<jk>public void</jk> onConfigChange(ConfigEvents events) {
			
			<jc>// Restart the microservice if anything was modified in one of our sections</jc>
			<jk>if</jk> (events.isSectionChanged(<js>"MySection"</js>))
				<jk>this</jk>.stop().start();
		}
	}
</p>