From c45eaba9de60ee434c2fda9130716b3d4251fde6 Mon Sep 17 00:00:00 2001
From: Christian Soronellas <christian.soronellas@atrapalo.com>
Date: Mon, 23 Nov 2015 01:31:28 +0100
Subject: [PATCH] Added usage examples of AMQPExchangeListener and
 AMQPMessageProducer on the README.md

---
 README.md | 169 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 169 insertions(+)

diff --git a/README.md b/README.md
index 7916f65..5181071 100644
--- a/README.md
+++ b/README.md
@@ -144,3 +144,172 @@ For the Doctrine Transactional Session, pass the EntityManager instance.
 As you can see, the use case creation and execution is the same as the non transactional, the only difference is the decoration with the Transactional Application Service.
 
 As a collateral benefit, the Doctrine Session manages internally the ```flush``` method, so you don't need to add a ```flush``` in your Domain neither your infrastructure.
+
+## Asynchronous AMQP listeners
+
+This library is capable to support asynchronous messaging in order to make Bounded Context capable to listen to other Bounded Context's events in an efficient way. The base for this is the both the **``[amqp](https://pecl.php.net/package/amqp)```** and the **```[react's event loop](https://github.com/reactphp/event-loop)```**. In addition, to support more efficient event loopings, we recommend the installation of one of this extensions
+
+* **[libevent](http://php.net/manual/es/book.libevent.php)**
+* **[libev](http://php.net/manual/es/intro.ev.php)**
+* **[event](http://php.net/manual/es/book.event.php)**
+
+The usage of any of this extensions is handled by ReactPHP's *event-loop* in a totally transparent way.
+
+### Example
+
+Supose we need to listen to the ```Acme\Billing\DomainModel\Order\OrderWasCreated``` event triggered via messaging from  another bounded context. The following, is an example of a AMQP exchange listener that listents to the ```Acme\Billing\DomainModel\Order\OrderWasCreated``` event.
+
+```php
+<?php
+
+namespace Acme\Inventory\Infrastructure\Messaging\Amqp;
+
+use stdClass;
+use AMQPQueue;
+use JMS\Serializer\Serializer;
+use League\Tactician\CommandBus;
+use React\EventLoop\LoopInterface;
+use Ddd\Infrastructure\Application\Notification\AmqpExchangeListener;
+
+class OrderWasCreatedListener extends AmqpExchangeListener
+{
+    private $commandBus;
+    
+    public function __construct(AMQPQueue $queue, LoopInterface $loop, Serializer $serializer, CommandBus $commandBus)
+    {
+        $this->commandBus = $commandBus;
+        
+        parent::construct($queue, $loop, $serializer);
+    }
+    
+    /**
+     * This method will be responsible to decide whether this listener listens to an specific
+     * event type or not, given an event type name
+     *
+     * @param string $typeName
+     *
+     * @return bool
+     */
+    protected function listensTo($typeName)
+    {
+        return 'Acme\Billing\DomainModel\Order\OrderWasCreated' === $typeName;
+    }
+
+    /**
+     * The action to perform
+     *
+     * @param stdClass $event
+     *
+     * @return void
+     */
+    protected function handle($event)
+    {
+        $this->commandBus->handle(new CreateOrder(
+            $event->order_id,
+            // ...
+        ));
+    }
+}
+```
+
+And this is a possible command to create AMQP workers
+
+```php
+<?php
+
+namespace AppBundle\Command;
+
+use AMQPConnection;
+use AMQPChannel;
+use React\EventLoop\Factory;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+use JMS\Serializer\Serializer;
+use League\Tactician\CommandBus;
+
+class OrderWasCreatedWorkerCommand extends Command
+{
+    private $serializer;
+    private $commandBus;
+    
+    public function __construct(Serializer $serializer, CommandBus $commandBus)
+    {
+        $this->serializer = $serializer;
+        $this->commandBus = $commandBus;
+        
+        parent::__construct();
+    }
+    
+    public function execute(InputInterface $input, OutputInterface $output)
+    {
+        $connection = new AMQPConnection([
+            'host' => 'example.host',
+            'vhost' => '/',
+            'port' => 5763,
+            'login' => 'user',
+            'password' => 'password'
+        ]);
+        $connection->connect();
+        
+        $queue = new AMQPQueue(new AMQPChannel($connection));
+        $queue->setName('events');
+        $queue->setFlags(AMQP_NOPARAM);
+        $queue->declareQueue();
+        
+        $loop = Factory::create();
+        
+        $listener = new OrderWasCreatedListener(
+            $queue,
+            $loop,
+            $serializer,
+            $this->commandBus
+        );
+        
+        $loop->run();
+    }
+}
+```
+
+## AMQP Message producer
+
+The intention of the AMQP message producer is to be composed in some other class. The following is an example of the usage of the AMQP message producer.
+
+```php
+<?php
+
+use Doctrine\ORM\Tools\Setup;
+use Doctrine\ORM\EntityManager;
+use Ddd\Infrastructure\Application\Notification\AmqpMessageProducer;
+use Ddd\Application\Notification\NotificationService;
+
+$connection = new AMQPConnection([
+    'host' => 'example.host',
+    'vhost' => '/',
+    'port' => 5763,
+    'login' => 'user',
+    'password' => 'password'
+]);
+$connection->connect();
+
+$exchange = new AMQPExchange(new AMQPChannel($connection));
+$exchange->setName('events');
+$exchange->declare();
+
+$config = Setup::createYAMLMetadataConfiguration([__DIR__."/src/Infrastructure/Application/Persistence/Doctrine/Config"], false);
+$entityManager = EntityManager::create(['driver' => 'pdo_sqlite', 'path' => __DIR__ . '/db.sqlite'], $config);
+
+$eventStore = $entityManager->getRepository('Ddd\Domain\Event\StoredEvent');
+$publishedMessageTracker = $entityManager->getRepository('Ddd\Domain\Event\PublishedMessage');
+$messageProducer = new AmqpMessageProducer($exchange);
+
+$notificationService = new NotificationService(
+    $eventStore,
+    $publishedMessageTracker,
+    $messageProducer
+);
+
+$notificationService->publish(/** ... **/);
+```
\ No newline at end of file