make the event bus optional

patchlevel · Mar 21, 2024 · 9af2628 · 9af2628
1 parent 3b6277f
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diff --git a/docs/pages/getting_started.md b/docs/pages/getting_started.md
@@ -278,7 +278,6 @@ After we have defined everything, we still have to plug the whole thing together
 
 ```php
 use Doctrine\DBAL\DriverManager;
-use Patchlevel\EventSourcing\EventBus\DefaultEventBus;
 use Patchlevel\EventSourcing\Projection\Engine\DefaultSubscriptionEngine;
 use Patchlevel\EventSourcing\Projection\Subscriber\MetadataSubscriberAccessorRepository;
 use Patchlevel\EventSourcing\Projection\Store\DoctrineSubscriptionStore;
@@ -320,12 +319,9 @@ $projectionist = new DefaultSubscriptionEngine(
     $projectorRepository,
 );
 
-$eventBus = DefaultEventBus::create();
-
 $repositoryManager = new DefaultRepositoryManager(
     $aggregateRegistry,
     $eventStore,
-    $eventBus,
 );
 
 $hotelRepository = $repositoryManager->get(Hotel::class);

diff --git a/docs/pages/repository.md b/docs/pages/repository.md
@@ -1,10 +1,8 @@
 # Repository
 
 A `repository` takes care of storing and loading the `aggregates`.
-He is also responsible for building [messages](event_bus.md) from the events and then dispatching them to the event bus.
-
-Every aggregate needs a repository to be stored. 
-And each repository is only responsible for one aggregate.
+He is also responsible for building [messages](event_bus.md) from the events 
+and optionally dispatching them to the event bus.
 
 ## Create a repository
 
@@ -13,8 +11,7 @@ This helps to build the repository correctly.
 
 The `DefaultRepositoryManager` needs some services to work. 
 For one, it needs [AggregateRootRegistry](aggregate.md#aggregate-root-registry) so that it knows which aggregates exist. 
-The [store](store.md), which is then given to the repository so that it can save and load the events at the end. 
-And the [EventBus](event_bus.md) to publish the new events.
+And the [store](store.md), which is then given to the repository so that it can save and load the events at the end.
 
 After plugging the `DefaultRepositoryManager` together, you can create the repository associated with the aggregate.
 
@@ -24,7 +21,6 @@ use Patchlevel\EventSourcing\Repository\DefaultRepositoryManager;
 $repositoryManager = new DefaultRepositoryManager(
     $aggregateRootRegistry,
     $store,
-    $eventBus
 );
 
 $repository = $repositoryManager->get(Profile::class);
@@ -34,6 +30,41 @@ $repository = $repositoryManager->get(Profile::class);
 
     The same repository instance is always returned for a specific aggregate.
 
+### Event Bus
+
+You can pass an event bus to the `DefaultRepositoryManager` to dispatch events synchronously.
+This is useful if you want to react to events in the same transaction.
+
+```php
+use Patchlevel\EventSourcing\EventBus\DefaultEventBus;
+use Patchlevel\EventSourcing\Repository\DefaultRepositoryManager;
+
+$eventBus = DefaultEventBus::create([/* listeners */]);
+
+$repositoryManager = new DefaultRepositoryManager(
+    $aggregateRootRegistry,
+    $store,
+    $eventBus,
+);
+
+$repository = $repositoryManager->get(Profile::class);
+```
+
+!!! warning
+
+    If you use the event bus, you should be aware that the events are dispatched synchronously.
+    You may encounter "at least once" problems.
+
+!!! note
+
+    You can find out more about event bus [here](event_bus.md).
+
+!!! tip
+
+    In most cases it is better to react to events asynchronously, 
+    that's why we recommend the subscription engine.
+    More information can be found [here](subscription.md).
+
 ### Snapshots
 
 Loading events for an aggregate is superfast. 
@@ -54,7 +85,7 @@ $snapshotStore = new DefaultSnapshotStore([
 $repositoryManager = new DefaultRepositoryManager(
     $aggregateRootRegistry,
     $store,
-    $eventBus,
+    null,
     $snapshotStore
 );
 
@@ -77,7 +108,7 @@ $decorator = new ApplicationIdDecorator();
 $repositoryManager = new DefaultRepositoryManager(
     $aggregateRootRegistry,
     $store,
-    $eventBus,
+    null,
     null,
     $decorator
 );
@@ -98,9 +129,7 @@ saving it or checking whether it exists.
 
 An `aggregate` can be `saved`. 
 All new events that have not yet been written to the database are fetched from the aggregate. 
-These events are then also append to the database. 
-After the events have been written, 
-the new events are dispatched on the [event bus](./event_bus.md).
+These events are then also append to the database.
 
 ```php
 use Patchlevel\EventSourcing\Aggregate\Uuid;
@@ -115,11 +144,6 @@ $repository->save($profile);
 
     All events are written to the database with one transaction in order to ensure data consistency.
 
-!!! tip
-
-    If you want to make sure that dispatching events and storing events is transaction safe, 
-    then you should look at the [outbox](outbox.md) pattern.
-
 ### Load an aggregate
 
 An `aggregate` can be loaded using the `load` method. 

diff --git a/src/Repository/DefaultRepository.php b/src/Repository/DefaultRepository.php
@@ -49,8 +49,8 @@ final class DefaultRepository implements Repository
     /** @param AggregateRootMetadata<T> $metadata */
     public function __construct(
         private Store $store,
-        private EventBus $eventBus,
         private readonly AggregateRootMetadata $metadata,
+        private EventBus|null $eventBus = null,
         private SnapshotStore|null $snapshotStore = null,
         private MessageDecorator|null $messageDecorator = null,
         ClockInterface|null $clock = null,
@@ -267,7 +267,7 @@ static function (object $event) use ($aggregateName, $aggregateId, &$playhead, $
                 }
 
                 $this->archive(...$messages);
-                $this->eventBus->dispatch(...$messages);
+                $this->eventBus?->dispatch(...$messages);
             });
 
             $this->aggregateIsValid[$aggregate] = true;

diff --git a/src/Repository/DefaultRepositoryManager.php b/src/Repository/DefaultRepositoryManager.php
@@ -32,7 +32,7 @@ final class DefaultRepositoryManager implements RepositoryManager
     public function __construct(
         private AggregateRootRegistry $aggregateRootRegistry,
         private Store $store,
-        private EventBus $eventBus,
+        private EventBus|null $eventBus = null,
         private SnapshotStore|null $snapshotStore = null,
         private MessageDecorator|null $messageDecorator = null,
         ClockInterface|null $clock = null,
@@ -66,8 +66,8 @@ public function get(string $aggregateClass): Repository
 
         return $this->instances[$aggregateClass] = new DefaultRepository(
             $this->store,
-            $this->eventBus,
             $this->metadataFactory->metadata($aggregateClass),
+            $this->eventBus,
             $this->snapshotStore,
             $this->messageDecorator,
             $this->clock,

diff --git a/tests/Benchmark/SimpleSetupBench.php b/tests/Benchmark/SimpleSetupBench.php
@@ -5,8 +5,6 @@
 namespace Patchlevel\EventSourcing\Tests\Benchmark;
 
 use Patchlevel\EventSourcing\Aggregate\AggregateRootId;
-use Patchlevel\EventSourcing\EventBus\DefaultEventBus;
-use Patchlevel\EventSourcing\EventBus\EventBus;
 use Patchlevel\EventSourcing\Message\Serializer\DefaultHeadersSerializer;
 use Patchlevel\EventSourcing\Repository\DefaultRepository;
 use Patchlevel\EventSourcing\Repository\Repository;
@@ -23,7 +21,6 @@
 final class SimpleSetupBench
 {
     private Store $store;
-    private EventBus $bus;
     private Repository $repository;
 
     private AggregateRootId $id;
@@ -32,8 +29,6 @@ public function setUp(): void
     {
         $connection = DbalManager::createConnection();
 
-        $this->bus = DefaultEventBus::create();
-
         $this->store = new DoctrineDbalStore(
             $connection,
             DefaultEventSerializer::createFromPaths([__DIR__ . '/BasicImplementation/Events']),
@@ -44,7 +39,7 @@ public function setUp(): void
             'eventstore',
         );
 
-        $this->repository = new DefaultRepository($this->store, $this->bus, Profile::metadata());
+        $this->repository = new DefaultRepository($this->store, Profile::metadata());
 
         $schemaDirector = new DoctrineSchemaDirector(
             $connection,

diff --git a/tests/Benchmark/SnapshotsBench.php b/tests/Benchmark/SnapshotsBench.php
@@ -5,8 +5,6 @@
 namespace Patchlevel\EventSourcing\Tests\Benchmark;
 
 use Patchlevel\EventSourcing\Aggregate\AggregateRootId;
-use Patchlevel\EventSourcing\EventBus\DefaultEventBus;
-use Patchlevel\EventSourcing\EventBus\EventBus;
 use Patchlevel\EventSourcing\Message\Serializer\DefaultHeadersSerializer;
 use Patchlevel\EventSourcing\Repository\DefaultRepository;
 use Patchlevel\EventSourcing\Repository\Repository;
@@ -26,7 +24,6 @@
 final class SnapshotsBench
 {
     private Store $store;
-    private EventBus $bus;
     private SnapshotStore $snapshotStore;
     private Repository $repository;
 
@@ -38,8 +35,6 @@ public function setUp(): void
     {
         $connection = DbalManager::createConnection();
 
-        $this->bus = DefaultEventBus::create();
-
         $this->store = new DoctrineDbalStore(
             $connection,
             DefaultEventSerializer::createFromPaths([__DIR__ . '/BasicImplementation/Events']),
@@ -54,7 +49,7 @@ public function setUp(): void
 
         $this->snapshotStore = new DefaultSnapshotStore(['default' => $this->adapter]);
 
-        $this->repository = new DefaultRepository($this->store, $this->bus, Profile::metadata(), $this->snapshotStore);
+        $this->repository = new DefaultRepository($this->store, Profile::metadata(), null, $this->snapshotStore);
 
         $schemaDirector = new DoctrineSchemaDirector(
             $connection,

diff --git a/tests/Benchmark/SplitStreamBench.php b/tests/Benchmark/SplitStreamBench.php
@@ -5,8 +5,6 @@
 namespace Patchlevel\EventSourcing\Tests\Benchmark;
 
 use Patchlevel\EventSourcing\Aggregate\AggregateRootId;
-use Patchlevel\EventSourcing\EventBus\DefaultEventBus;
-use Patchlevel\EventSourcing\EventBus\EventBus;
 use Patchlevel\EventSourcing\Message\Serializer\DefaultHeadersSerializer;
 use Patchlevel\EventSourcing\Metadata\Event\AttributeEventMetadataFactory;
 use Patchlevel\EventSourcing\Repository\DefaultRepository;
@@ -27,7 +25,6 @@
 final class SplitStreamBench
 {
     private Store $store;
-    private EventBus $bus;
     private Repository $repository;
 
     private AggregateRootId $id;
@@ -36,8 +33,6 @@ public function setUp(): void
     {
         $connection = DbalManager::createConnection();
 
-        $this->bus = DefaultEventBus::create();
-
         $this->store = new DoctrineDbalStore(
             $connection,
             DefaultEventSerializer::createFromPaths([__DIR__ . '/BasicImplementation/Events']),
@@ -50,9 +45,9 @@ public function setUp(): void
 
         $this->repository = new DefaultRepository(
             $this->store,
-            $this->bus,
             Profile::metadata(),
             null,
+            null,
             new SplitStreamDecorator(
                 new AttributeEventMetadataFactory(),
             ),

diff --git a/tests/Benchmark/SubscriptionEngineBench.php b/tests/Benchmark/SubscriptionEngineBench.php
@@ -5,8 +5,6 @@
 namespace Patchlevel\EventSourcing\Tests\Benchmark;
 
 use Patchlevel\EventSourcing\Aggregate\AggregateRootId;
-use Patchlevel\EventSourcing\EventBus\DefaultEventBus;
-use Patchlevel\EventSourcing\EventBus\EventBus;
 use Patchlevel\EventSourcing\Message\Serializer\DefaultHeadersSerializer;
 use Patchlevel\EventSourcing\Repository\DefaultRepository;
 use Patchlevel\EventSourcing\Repository\Repository;
@@ -30,7 +28,6 @@
 final class SubscriptionEngineBench
 {
     private Store $store;
-    private EventBus $bus;
     private Repository $repository;
 
     private SubscriptionEngine $subscriptionEngine;
@@ -41,8 +38,6 @@ public function setUp(): void
     {
         $connection = DbalManager::createConnection();
 
-        $this->bus = DefaultEventBus::create();
-
         $this->store = new DoctrineDbalStore(
             $connection,
             DefaultEventSerializer::createFromPaths([__DIR__ . '/BasicImplementation/Events']),
@@ -55,7 +50,7 @@ public function setUp(): void
             'eventstore',
         );
 
-        $this->repository = new DefaultRepository($this->store, $this->bus, Profile::metadata());
+        $this->repository = new DefaultRepository($this->store, Profile::metadata());
 
         $subscriptionStore = new DoctrineSubscriptionStore(
             $connection,

diff --git a/tests/Benchmark/blackfire.php b/tests/Benchmark/blackfire.php
@@ -4,7 +4,6 @@
 
 use Doctrine\DBAL\Driver\PDO\SQLite\Driver;
 use Doctrine\DBAL\DriverManager;
-use Patchlevel\EventSourcing\EventBus\DefaultEventBus;
 use Patchlevel\EventSourcing\Message\Serializer\DefaultHeadersSerializer;
 use Patchlevel\EventSourcing\Repository\DefaultRepository;
 use Patchlevel\EventSourcing\Schema\DoctrineSchemaDirector;
@@ -26,8 +25,6 @@
     'path' => DB_PATH,
 ]);
 
-$bus = DefaultEventBus::create();
-
 $store = new DoctrineDbalStore(
     $connection,
     DefaultEventSerializer::createFromPaths([__DIR__ . '/BasicImplementation/Events']),
@@ -38,7 +35,7 @@
     'eventstore',
 );
 
-$repository = new DefaultRepository($store, $bus, Profile::metadata());
+$repository = new DefaultRepository($store, Profile::metadata());
 
 $schemaDirector = new DoctrineSchemaDirector(
     $connection,

diff --git a/tests/Integration/BankAccountSplitStream/IntegrationTest.php b/tests/Integration/BankAccountSplitStream/IntegrationTest.php
@@ -5,7 +5,6 @@
 namespace Patchlevel\EventSourcing\Tests\Integration\BankAccountSplitStream;
 
 use Doctrine\DBAL\Connection;
-use Patchlevel\EventSourcing\EventBus\DefaultEventBus;
 use Patchlevel\EventSourcing\Message\Serializer\DefaultHeadersSerializer;
 use Patchlevel\EventSourcing\Metadata\AggregateRoot\AggregateRootRegistry;
 use Patchlevel\EventSourcing\Metadata\Event\AttributeEventMetadataFactory;
@@ -63,12 +62,10 @@ public function testSuccessful(): void
             new MetadataSubscriberAccessorRepository([$bankAccountProjector]),
         );
 
-        $eventBus = DefaultEventBus::create([$bankAccountProjector]);
-
         $manager = new DefaultRepositoryManager(
             new AggregateRootRegistry(['bank_account' => BankAccount::class]),
             $store,
-            $eventBus,
+            null,
             null,
             new ChainMessageDecorator([
                 new SplitStreamDecorator(new AttributeEventMetadataFactory()),
@@ -91,6 +88,8 @@ public function testSuccessful(): void
         $bankAccount->addBalance(500);
         $repository->save($bankAccount);
 
+        $engine->run();
+
         $result = $this->connection->fetchAssociative('SELECT * FROM projection_bank_account WHERE id = ?', ['1']);
 
         self::assertIsArray($result);
@@ -102,7 +101,7 @@ public function testSuccessful(): void
         $manager = new DefaultRepositoryManager(
             new AggregateRootRegistry(['bank_account' => BankAccount::class]),
             $store,
-            $eventBus,
+            null,
             null,
             new ChainMessageDecorator([
                 new SplitStreamDecorator(new AttributeEventMetadataFactory()),
@@ -125,6 +124,8 @@ public function testSuccessful(): void
         $bankAccount->addBalance(200);
         $repository->save($bankAccount);
 
+        $engine->run();
+
         $result = $this->connection->fetchAssociative('SELECT * FROM projection_bank_account WHERE id = ?', ['1']);
 
         self::assertIsArray($result);
@@ -136,7 +137,7 @@ public function testSuccessful(): void
         $manager = new DefaultRepositoryManager(
             new AggregateRootRegistry(['bank_account' => BankAccount::class]),
             $store,
-            $eventBus,
+            null,
             null,
             new ChainMessageDecorator([
                 new SplitStreamDecorator(new AttributeEventMetadataFactory()),