config.yml

services:
    notification:
        class: Itembase\CoreBundle\Services\NotificationService
        arguments: [@mailer, @doctrine.orm.entity_manager, @templating]

// as you can see we are injecting @mailer, @doctrine.orm.entity_manager, @templating
// You'll find this again in NotificationService constructor.
// that is a nice way to pass services arround.

Itembase\CoreBundle\Command\ActivityStreamUpdaterCommand.php

// this command uses the Notification Service

class ActivityStreamUpdaterCommand extends ContainerAwareCommand
{
	private $silentMode;

	private function sendOutNotification($action, $payload, $user, $actorIdentifier, $actorName)
	{	
		if ($user->getUsername() != $actorIdentifier) {	

// get a instance of NotificationService
			$notifier = $this->getContainer()->get('notification');

// now use the NotificationServer 
			$notifier->sendNotification(
				$user, // Receiver

Itembase\CoreBundle\Services\NotificationService.php

namespace Itembase\CoreBundle\Services;

class NotificationService
{

	private $mailer;
	private $em;
	private $templating;
	

// constructor with params, that will be injected.
	public function __construct(\Swift_Mailer $mailer, EntityManager $em, EngineInterface $templating)
	{    
	    $this->em = $em;
	    $this->mailer = $mailer;
	    $this->templating = $templating;
	}

ItembaseCoreBundleCommandActivityStreamUpdaterCommand.php

<?
// this command uses the Notification Service

class ActivityStreamUpdaterCommand extends ContainerAwareCommand
{
	private $silentMode;

	private function sendOutNotification($action, $payload, $user, $actorIdentifier, $actorName)
	{	
		if ($user->getUsername() != $actorIdentifier) {	

// get a instance of NotificationService
			$notifier = $this->getContainer()->get('notification');

// now use the NotificationServer 
			$notifier->sendNotification(
				$user, // Receiver

ItembaseCoreBundleServicesNotificationService.php

<?
namespace Itembase\CoreBundle\Services;

class NotificationService
{

	private $mailer;
	private $em;
	private $templating;
	

// constructor with params, that will be injected.
	public function __construct(\Swift_Mailer $mailer, EntityManager $em, EngineInterface $templating)
	{    
	    $this->em = $em;
	    $this->mailer = $mailer;
	    $this->templating = $templating;
	}