[Messenger] Add RunProcessMessage

Author: alexandre-daubois

messenger.rst

@@ -1897,6 +1897,42 @@ on a case-by-case basis via the :class:`Symfony\\Component\\Messenger\\Stamp\\Se
     provides that control. See `SymfonyCasts' message serializer tutorial`_ for
     details.
 
+Running External Processes
+--------------------------
+
+Messenger comes with a handy helper to easily run external processes by
+dispatching a message. This takes advantages of the
+:doc:`Process component </components/process>`. By dispatching a
+:class:`Symfony\\Component\\Process\\Messenger\\RunProcessMessage`, Messenger
+will take care of creating a new process with the parameters you passed
+to the message::
+
+    use Symfony\Component\Messenger\MessageBusInterface;
+    use Symfony\Component\Process\Messenger\RunProcessMessage;
+
+    class CleanUpService
+    {
+        public function __construct(private MessageBusInterface $bus)
+        {
+        }
+
+        public function cleanUp(): void
+        {
+            $this->bus->dispatch(new RunProcessMessage(['rm', '-rf', 'var/log/temp/*'], cwd: '/my/custom/working-dir'));
+
+            // ...
+        }
+    }
+
+Once handled, the message will contain many useful information such as the exit
+code or the output of the process. You can refer to the page dedicated on
+:doc:`handler results </messenger/handler_results>` for more information.
+
+.. versionadded:: 6.4
+
+    The :class:`Symfony\\Component\\Process\\Messenger\\RunProcessMessage`
+    class was introduced in Symfony 6.4.
+
 Customizing Handlers
 --------------------