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Microservice Listeners

The lifecycle methods of the Microservice class are non-final so that subclasses can override them. A listener interface offers the same hooks without subclassing.

When to use it​

Use a listener to run code when the microservice starts or stops, or to restart it when a section of the config file changes.

Example​

import org.apache.juneau.config.event.*;
import org.apache.juneau.microservice.*;

public class MyMicroserviceListener extends BasicMicroserviceListener {

    @Override /* MicroserviceListener */
    public void onStart(Microservice microservice) {
        System.out.println("Started");
    }

    @Override /* MicroserviceListener */
    public void onConfigChange(Microservice microservice, ConfigEvents events) {

        // Restart the microservice if anything was modified in one of our sections
        try {
            if (events.isSectionModified("MySection"))
                microservice.stop().start();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
}

Options​

Microservice.Builderlistener(MicroserviceListener)MicroserviceListeneronStart(Microservice) onStop(Microservice) onConfigChange(Microservice,ConfigEvents)BasicMicroserviceListener

Note that the Microservice.onConfigChange(ConfigEvents) method can also be overridden to react to configuration changes as well:

public class MyMicroservice extends Microservice {

    @Override /* MicroserviceListener */
    public void onConfigChange(ConfigEvents events) {

        // Restart the microservice if anything was modified in one of our sections
        if (events.isSectionModified("MySection"))
            this.stop().start();
    }
}

See also​