.. index:: single: Messenger
Symfony's Messenger provides a message bus and some routing capabilities to send messages within your application and through transports such as message queues. Before using it, read the :doc:`Messenger component docs </components/messenger>` to get familiar with its concepts.
In applications using :doc:`Symfony Flex </setup/flex>`, run this command to install messenger before using it:
$ composer require messenger
Once enabled, the message_bus
service can be injected in any service where
you need it, like in a controller:
// src/Controller/DefaultController.php namespace App\Controller; use App\Message\SendNotification; use Symfony\Bundle\FrameworkBundle\Controller\AbstractController; use Symfony\Component\Messenger\MessageBusInterface; class DefaultController extends AbstractController { public function index(MessageBusInterface $bus) { $bus->dispatch(new SendNotification('A string to be sent...')); } }
In order to do something when your message is dispatched, you need to create a
message handler. It's a class with an __invoke
method:
// src/MessageHandler/MyMessageHandler.php namespace App\MessageHandler; class MyMessageHandler { public function __invoke(MyMessage $message) { // do something with it. } }
Once you've created your handler, you need to register it:
.. configuration-block:: .. code-block:: yaml # config/services.yaml services: App\MessageHandler\MyMessageHandler: tags: [messenger.message_handler] .. code-block:: xml <!-- config/services.xml --> <?xml version="1.0" encoding="UTF-8" ?> <container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"> <services> <service id="App\MessageHandler\MyMessageHandler"> <tag name="messenger.message_handler" /> </service> </services> </container> .. code-block:: php // config/services.php use App\MessageHandler\MyMessageHandler; $container->register(MyMessageHandler::class) ->addTag('messenger.message_handler');
Note
If the message cannot be guessed from the handler's type-hint, use the
handles
attribute on the tag.
By default, messages are processed as soon as they are dispatched. If you prefer to process messages asynchronously, you must configure a transport. These transports communicate with your application via queuing systems or third parties. The built-in AMQP transport allows you to communicate with most of the AMQP brokers such as RabbitMQ.
Note
If you need more message brokers, you should have a look at Enqueue's transport which supports things like Kafka, Amazon SQS or Google Pub/Sub.
A transport is registered using a "DSN", which is a string that represents the connection credentials and configuration. By default, when you've installed the messenger component, the following configuration should have been created:
.. configuration-block:: .. code-block:: yaml # config/packages/messenger.yaml framework: messenger: transports: amqp: "%env(MESSENGER_TRANSPORT_DSN)%" .. code-block:: xml <!-- config/packages/messenger.xml --> <?xml version="1.0" encoding="UTF-8" ?> <container xmlns="http://symfony.com/schema/dic/symfony" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:framework="http://symfony.com/schema/dic/symfony" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/symfony http://symfony.com/schema/dic/symfony/symfony-1.0.xsd"> <framework:config> <framework:messenger> <framework:transport name="amqp" dsn="%env(MESSENGER_TRANSPORT_DSN)%" /> </framework:messenger> </framework:config> </container> .. code-block:: php // config/packages/messenger.php $container->loadFromExtension('framework', array( 'messenger' => array( 'transports' => array( 'amqp' => '%env(MESSENGER_TRANSPORT_DSN)%', ), ), ));
# .env
###> symfony/messenger ###
MESSENGER_DSN=amqp://guest:guest@localhost:5672/%2f/messages
###< symfony/messenger ###
This is enough to allow you to route your message to the amqp
transport.
This will also configure the following services for you:
- A
messenger.sender.amqp
sender to be used when routing messages; - A
messenger.receiver.amqp
receiver to be used when consuming messages.
Note
In order to use Symfony's built-in AMQP transport, you will need the Serializer Component. Ensure that it is installed with:
$ composer require symfony/serializer-pack
Instead of calling a handler, you have the option to route your message(s) to a sender. Part of a transport, it is responsible for sending your message somewhere. You can configure which message is routed to which sender with the following configuration:
.. configuration-block:: .. code-block:: yaml # config/packages/messenger.yaml framework: messenger: routing: 'My\Message\Message': amqp # The name of the defined transport .. code-block:: xml <!-- config/packages/messenger.xml --> <?xml version="1.0" encoding="UTF-8" ?> <container xmlns="http://symfony.com/schema/dic/symfony" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:framework="http://symfony.com/schema/dic/symfony" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/symfony http://symfony.com/schema/dic/symfony/symfony-1.0.xsd"> <framework:config> <framework:messenger> <framework:routing message-class="My\Message\Message"> <framework:sender service="amqp" /> </framework:routing> </framework:messenger> </framework:config> </container> .. code-block:: php // config/packages/messenger.php $container->loadFromExtension('framework', array( 'messenger' => array( 'routing' => array( 'My\Message\Message' => 'amqp', ), ), ));
Such configuration would only route the My\Message\Message
message to be
asynchronous, the rest of the messages would still be directly handled.
You can route all classes of messages to the same sender using an asterisk instead of a class name:
.. configuration-block:: .. code-block:: yaml # config/packages/messenger.yaml framework: messenger: routing: 'My\Message\MessageAboutDoingOperationalWork': another_transport '*': amqp .. code-block:: xml <!-- config/packages/messenger.xml --> <?xml version="1.0" encoding="UTF-8" ?> <container xmlns="http://symfony.com/schema/dic/symfony" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:framework="http://symfony.com/schema/dic/symfony" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/symfony http://symfony.com/schema/dic/symfony/symfony-1.0.xsd"> <framework:config> <framework:messenger> <framework:routing message-class="My\Message\Message"> <framework:sender service="another_transport" /> </framework:routing> <framework:routing message-class="*"> <framework:sender service="amqp" /> </framework:routing> </framework:messenger> </framework:config> </container> .. code-block:: php // config/packages/messenger.php $container->loadFromExtension('framework', array( 'messenger' => array( 'routing' => array( 'My\Message\Message' => 'another_transport', '*' => 'amqp', ), ), ));
A class of messages can also be routed to multiple senders by specifying a list:
.. configuration-block:: .. code-block:: yaml # config/packages/messenger.yaml framework: messenger: routing: 'My\Message\ToBeSentToTwoSenders': [amqp, audit] .. code-block:: xml <!-- config/packages/messenger.xml --> <container xmlns="http://symfony.com/schema/dic/symfony" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:framework="http://symfony.com/schema/dic/symfony" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/symfony http://symfony.com/schema/dic/symfony/symfony-1.0.xsd"> <framework:config> <framework:messenger> <framework:routing message-class="My\Message\ToBeSentToTwoSenders"> <framework:sender service="amqp" /> <framework:sender service="audit" /> </framework:routing> </framework:messenger> </framework:config> </container> .. code-block:: php // config/packages/messenger.php $container->loadFromExtension('framework', array( 'messenger' => array( 'routing' => array( 'My\Message\ToBeSentToTwoSenders' => array('amqp', 'audit'), ), ), ));
By specifying a null
sender, you can also route a class of messages to a sender
while still having them passed to their respective handler:
.. configuration-block:: .. code-block:: yaml # config/packages/messenger.yaml framework: messenger: routing: 'My\Message\ThatIsGoingToBeSentAndHandledLocally': [amqp, ~] .. code-block:: xml <!-- config/packages/messenger.xml --> <container xmlns="http://symfony.com/schema/dic/symfony" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:framework="http://symfony.com/schema/dic/symfony" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/symfony http://symfony.com/schema/dic/symfony/symfony-1.0.xsd"> <framework:config> <framework:messenger> <framework:routing message-class="My\Message\ThatIsGoingToBeSentAndHandledLocally"> <framework:sender service="amqp" /> <framework:sender service="" /> </framework:routing> </framework:messenger> </framework:config> </container> .. code-block:: php // config/packages/messenger.php $container->loadFromExtension('framework', array( 'messenger' => array( 'routing' => array( 'My\Message\ThatIsGoingToBeSentAndHandledLocally' => array('amqp', null), ), ), ));
Once your messages have been routed, you will like to consume your messages in most
of the cases. To do so, you can use the messenger:consume-messages
command
like this:
$ bin/console messenger:consume-messages amqp
The first argument is the receiver's service name. It might have been created by
your transports
configuration or it can be your own receiver.
If you are interested in architectures like CQRS, you might want to have multiple buses within your application.
You can create multiple buses (in this example, a command bus and an event bus) like this:
.. configuration-block:: .. code-block:: yaml # config/packages/messenger.yaml framework: messenger: # The bus that is going to be injected when injecting MessageBusInterface: default_bus: messenger.bus.commands # Create buses buses: messenger.bus.commands: ~ messenger.bus.events: ~ .. code-block:: xml <!-- config/packages/messenger.xml --> <container xmlns="http://symfony.com/schema/dic/symfony" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:framework="http://symfony.com/schema/dic/symfony" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/symfony http://symfony.com/schema/dic/symfony/symfony-1.0.xsd"> <framework:config> <framework:messenger default-bus="messenger.bus.commands"> <framework:bus name="messenger.bus.commands" /> <framework:bus name="messenger.bus.events" /> </framework:messenger> </framework:config> </container> .. code-block:: php // config/packages/messenger.php $container->loadFromExtension('framework', array( 'messenger' => array( 'default_bus' => 'messenger.bus.commands', 'buses' => array( 'messenger.bus.commands' => null, 'messenger.bus.events' => null, ), ), ));
This will generate the messenger.bus.commands
and messenger.bus.events
services
that you can inject in your services.
Auto-wiring is a great feature that allows you to reduce the amount of configuration required for your service container to be created. When using multiple buses, by default, the auto-wiring will not work as it won't know which bus to inject in your own services.
In order to clarify this, you can use the DependencyInjection's binding capabilities to clarify which bus will be injected based on the argument's name:
.. configuration-block:: .. code-block:: yaml # config/services.yaml services: _defaults: # ... bind: $commandBus: '@messenger.bus.commands' $eventBus: '@messenger.bus.events' .. code-block:: xml <!-- config/services.xml --> <?xml version="1.0" encoding="UTF-8" ?> <container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"> <services> <defaults> <bind key="$commandBus" type="service" id="messenger.bus.commands" /> <bind key="$commandBus" type="service" id="messenger.bus.events" /> </defaults> </services> </container>
What happens when you dispatch a message to a message bus(es) depends on its collection of middleware (and their order). By default, the middleware configured for each bus looks like this:
logging
middleware. Responsible for logging the beginning and the end of the message within the bus;- _Your own collection of middleware;
route_messages
middleware. Will route the messages you configured to their corresponding sender and stop the middleware chain;call_message_handler
middleware. Will call the message handler(s) for the given message.
As described in the component documentation, you can add your own middleware within the buses to add some extra capabilities like this:
.. configuration-block:: .. code-block:: yaml # config/packages/messenger.yaml framework: messenger: buses: messenger.bus.default: middleware: - 'App\Middleware\MyMiddleware' - 'App\Middleware\AnotherMiddleware' .. code-block:: xml <!-- config/packages/messenger.xml --> <container xmlns="http://symfony.com/schema/dic/symfony" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:framework="http://symfony.com/schema/dic/symfony" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/symfony http://symfony.com/schema/dic/symfony/symfony-1.0.xsd"> <framework:config> <framework:messenger> <framework:bus name="messenger.bus.default"> <framework:middleware id="App\Middleware\MyMiddleware" /> <framework:middleware id="App\Middleware\AnotherMiddleware" /> </framework:bus> </framework:messenger> </framework:config> </container> .. code-block:: php // config/packages/messenger.php $container->loadFromExtension('framework', array( 'messenger' => array( 'buses' => array( 'messenger.bus.default' => array( 'middleware' => array( 'App\Middleware\MyMiddleware', 'App\Middleware\AnotherMiddleware', ), ), ), ), ));
Note that if the service is abstract, a different instance of service will be created per bus.
If you don't want the default collection of middleware to be present on your bus, you can disable them like this:
.. configuration-block:: .. code-block:: yaml # config/packages/messenger.yaml framework: messenger: buses: messenger.bus.default: default_middleware: false .. code-block:: xml <!-- config/packages/messenger.xml --> <container xmlns="http://symfony.com/schema/dic/symfony" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:framework="http://symfony.com/schema/dic/symfony" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/symfony http://symfony.com/schema/dic/symfony/symfony-1.0.xsd"> <framework:config> <framework:messenger> <framework:bus name="messenger.bus.default" default-middleware="false" /> </framework:messenger> </framework:config> </container> .. code-block:: php // config/packages/messenger.php $container->loadFromExtension('framework', array( 'messenger' => array( 'buses' => array( 'messenger.bus.default' => array( 'default_middleware' => false, ), ), ), ));
Some third-party bundles and libraries provide configurable middleware via factories. Defining such requires a two-step configuration based on Symfony's :doc:`dependency injection </service_container>` features:
.. configuration-block:: .. code-block:: yaml # config/services.yaml services: # Step 1: a factory class is registered as a service with the required # dependencies to instantiate a middleware doctrine.orm.messenger.middleware_factory.transaction: class: Symfony\Bridge\Doctrine\Messenger\DoctrineTransactionMiddlewareFactory arguments: ['@doctrine'] # Step 2: an abstract definition that will call the factory with default # arguments or the ones provided in the middleware config messenger.middleware.doctrine_transaction_middleware: class: Symfony\Bridge\Doctrine\Messenger\DoctrineTransactionMiddleware factory: 'doctrine.orm.messenger.middleware_factory.transaction:createMiddleware' abstract: true # the default arguments to use when none provided from config. Example: # middleware: # - doctrine_transaction_middleware: ~ arguments: ['default'] .. code-block:: xml <!-- cconfig/services.xml --> <?xml version="1.0" encoding="UTF-8" ?> <container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"> <services> <!-- Step 1: a factory class is registered as a service with the required dependencies to instantiate a middleware --> <service id="doctrine.orm.messenger.middleware_factory.transaction" class="Symfony\Bridge\Doctrine\Messenger\DoctrineTransactionMiddlewareFactory"> <argument type="service" id="doctrine" /> </service> <!-- Step 2: an abstract definition that will call the factory with default arguments or the ones provided in the middleware config --> <service id="messenger.middleware.doctrine_transaction_middleware" class="Symfony\Bridge\Doctrine\Messenger\DoctrineTransactionMiddleware" abstract="true"> <factory service="doctrine.orm.messenger.middleware_factory.transaction" method="createMiddleware" /> <argument>default</argument> </service> </services> </container> .. code-block:: php // config/services.php use Symfony\Bridge\Doctrine\Messenger\DoctrineTransactionMiddleware; use Symfony\Bridge\Doctrine\Messenger\DoctrineTransactionMiddlewareFactory; use Symfony\Component\DependencyInjection\Reference; // Step 1: a factory class is registered as a service with the required // dependencies to instantiate a middleware $container ->register('doctrine.orm.messenger.middleware_factory.transaction', DoctrineTransactionMiddlewareFactory::class) ->setArguments(array(new Reference('doctrine'))); // Step 2: an abstract definition that will call the factory with default // arguments or the ones provided in the middleware config $container->register('messenger.middleware.doctrine_transaction_middleware', DoctrineTransactionMiddleware::class) ->setFactory(array( new Reference('doctrine.orm.messenger.middleware_factory.transaction'), 'createMiddleware' )) ->setAbstract(true) ->setArguments(array('default'));
The "default" value in this example is the name of the entity manager to use,
which is the argument expected by the
Symfony\Bridge\Doctrine\Messenger\DoctrineTransactionMiddlewareFactory::createMiddleware
method.
Then you can reference and configure the
messenger.middleware.doctrine_transaction_middleware
service as a middleware:
.. configuration-block:: .. code-block:: yaml # config/packages/messenger.yaml framework: messenger: buses: command_bus: middleware: # Using defaults - doctrine_transaction_middleware # Using another entity manager - doctrine_transaction_middleware: ['custom'] .. code-block:: xml <!-- config/packages/messenger.xml --> <container xmlns="http://symfony.com/schema/dic/symfony" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:framework="http://symfony.com/schema/dic/symfony" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/symfony http://symfony.com/schema/dic/symfony/symfony-1.0.xsd"> <framework:config> <framework:messenger> <framework:bus name="command_bus"> <!-- Using defaults --> <framework:middleware id="doctrine_transaction_middleware" /> <!-- Using another entity manager --> <framework:middleware id="doctrine_transaction_middleware"> <framework:argument>custom</framework:argument> </framework:middleware> </framework:bus> </framework:messenger> </framework:config> </container> .. code-block:: php // config/packages/messenger.php $container->loadFromExtension('framework', array( 'messenger' => array( 'buses' => array( 'command_bus' => array( 'middleware' => array( // Using defaults 'doctrine_transaction_middleware', // Using another entity manager array('id' => 'doctrine_transaction_middleware', 'arguments' => array('custom')), ), ), ), ), ));
Note
The doctrine_transaction_middleware
shortcut is a convention. The real
service id is prefixed with the messenger.middleware.
namespace.
Note
Middleware factories only allow scalar and array arguments in config (no references to other services). For most advanced use-cases, register a concrete definition of the middleware manually and use its id.
Tip
The doctrine_transaction_middleware
is a built-in middleware wired
automatically when the DoctrineBundle and the Messenger component are
installed and enabled.
Once you have written your transport's sender and receiver, you can register your transport factory to be able to use it via a DSN in the Symfony application.
You need to give FrameworkBundle the opportunity to create your transport from a DSN. You will need a transport factory:
use Symfony\Component\Messenger\Transport\TransportFactoryInterface; use Symfony\Component\Messenger\Transport\TransportInterface; use Symfony\Component\Messenger\Transport\ReceiverInterface; use Symfony\Component\Messenger\Transport\SenderInterface; class YourTransportFactory implements TransportFactoryInterface { public function createTransport(string $dsn, array $options): TransportInterface { return new YourTransport(/* ... */); } public function supports(string $dsn, array $options): bool { return 0 === strpos($dsn, 'my-transport://'); } }
The transport object needs to implement the TransportInterface
(which simply combines
the SenderInterface
and ReceiverInterface
). It will look like this:
class YourTransport implements TransportInterface { public function send($message) : void { // ... } public function receive(callable $handler) : void { // ... } public function stop() : void { // ... } }
.. configuration-block:: .. code-block:: yaml # config/services.yaml services: Your\Transport\YourTransportFactory: tags: [messenger.transport_factory] .. code-block:: xml <!-- cconfig/services.xml --> <?xml version="1.0" encoding="UTF-8" ?> <container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"> <services> <service id="Your\Transport\YourTransportFactory"> <tag name="messenger.transport_factory" /> </service> </services> </container> .. code-block:: php // config/services.php use Your\Transport\YourTransportFactory; $container->register(YourTransportFactory::class) ->setTags(array('messenger.transport_factory'));
Within the framework.messenger.transports.*
configuration, create your
named transport using your own DSN:
.. configuration-block:: .. code-block:: yaml # config/packages/messenger.yaml framework: messenger: transports: yours: 'my-transport://...' .. code-block:: xml <!-- config/packages/messenger.xml --> <?xml version="1.0" encoding="UTF-8" ?> <container xmlns="http://symfony.com/schema/dic/symfony" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:framework="http://symfony.com/schema/dic/symfony" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/symfony http://symfony.com/schema/dic/symfony/symfony-1.0.xsd"> <framework:config> <framework:messenger> <framework:transport name="yours" dsn="my-transport://..." /> </framework:messenger> </framework:config> </container> .. code-block:: php // config/packages/messenger.php $container->loadFromExtension('framework', array( 'messenger' => array( 'transports' => array( 'yours' => 'my-transport://...', ), ), ));
In addition of being able to route your messages to the yours
sender, this
will give you access to the following services:
messenger.sender.yours
: the sender;messenger.receiver.yours
: the receiver.