DebugService.groovy

package todosample

import grails.events.Listener

class DebugService {
    @Listener
    def packageWarStart() {
        println "[DebugService] Packaging started"
    }

    @Listener
    def packageWarStatus(String msg) {
        println "[DebugService] Packaging status: ${msg}"
    }
}

TodoEvents.groovy

import todosample.Todo

events = {
    'afterInsert' browser:true, filter:Todo
    'afterDelete' browser:true, filter:Todo
    'afterUpdate' browser:true, filter:Todo
    deployStart browser: true
    deployEnd browser: true
    packageWarStart browser: true
    packageWarStatus browser: true
    packageWarEnd browser: true
}