Setup prerequisites

Author: Jeroen de Graaf

README.md

@@ -2,4 +2,97 @@
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-Gember Event Sourcing Symfony Bundle for ([gember/event-sourcing](https://github.com/GemberPHP/event-sourcing)).
+Gember Event Sourcing Symfony Bundle for ([gember/event-sourcing](https://github.com/GemberPHP/event-sourcing)).
+
+## Prerequisites
+This package requires Symfony `^7.1`.
+
+Several additional packages should be installed and configured in Symfony as well:
+
+#### Symfony Messenger (`symfony/messenger`)
+At least one message bus should be configured, with the name `@event.bus`. 
+
+When this bus is configured, Gember Event Sourcing works out of the box.
+However, when a different event bus is preferred, it can be overwritten by configuration (`gember_event_sourcing.yaml`).
+```yaml
+gember_event_sourcing:
+    message_bus:
+        symfony:
+            event_bus: '@event.bus'
+```
+Note: It must be a service implementing `Symfony\Component\Messenger\MessageBusInterface`.
+
+#### Symfony Cache (`symfony/cache`)
+Gember Event Sourcing makes use of `@cache.app`. 
+This cache service is automatically configured when using Symfony framework including `symfony/cache`.
+
+When this cache service is configured, Gember Event Sourcing works out of the box.
+However, when a different cache pool is preferred, it can be overwritten by configuration (`gember_event_sourcing.yaml`):
+```yaml
+gember_event_sourcing:
+    cache:
+        enabled: true
+        psr6: '@cache.app'
+        
+        # Or set a PSR-16 compatible cache layer of your choice
+        # psr16: '@some.psr16.service'
+```
+Note: It must be a service implementing `Psr\Cache\CacheItemPoolInterface` (PSR-6) or `Psr\SimpleCache\CacheInterface` (PSR-16).
+
+#### Symfony Serializer (`symfony/serializer`)
+Gember Event Sourcing makes use of `@serializer`.
+This serializer service is automatically configured when using Symfony framework including `symfony/serializer`.
+
+When this serializer service is configured, Gember Event Sourcing works out of the box.
+However, when a different serializer is preferred, it can be overwritten by configuration (`gember_event_sourcing.yaml`):
+```yaml
+gember_event_sourcing:
+    serializer:
+        symfony:
+          serializer: '@serializer'
+```
+Note: It must be a service implementing `Symfony\Component\Serializer\SerializerInterface`.
+
+#### Doctrine DBAL/ORM (`doctrine/dbal`, `doctrine/orm`)
+Gember Event Sourcing makes use of `@doctrine.dbal.default_connection`.
+This connection service is automatically configured when using Symfony framework including `doctrine/dbal` or `doctrine/orm`.
+
+When this connection service is configured, Gember Event Sourcing works out of the box.
+However, when a different Doctrine connection is preferred, it can be overwritten by configuration (`gember_event_sourcing.yaml`):
+```yaml
+gember_event_sourcing:
+  event_store:
+    rdbms:
+      doctrine_dbal:
+        connection: '@doctrine.dbal.default_connection'
+```
+Note: It must be a service implementing `Doctrine\DBAL\Connection`.
+
+#### Symfony UID (`symfony/uid`)
+Gember Event Sourcing makes use of `@Symfony\Component\Uid\Factory\UuidFactory` or `Symfony\Component\Uid\Factory\UlidFactory`.
+
+These factories are automatically configured when using Symfony framework including `symfony/uid`.
+
+By default, the UUID factory is used in Gember Event Sourcing. 
+However, if the ULID factory is preferred, it can be overwritten by configuration (`gember_event_sourcing.yaml`):
+```yaml
+gember_event_sourcing:
+  generator:
+    identity:
+      # Use Gember alias of @Symfony\Component\Uid\Factory\UuidFactory:
+      service: '@gember.identity_generator_symfony.uuid.symfony_uuid_identity_generator'
+
+      # Or use Gember alias of @Symfony\Component\Uid\Factory\UlidFactory:
+      # service: '@gember.identity_generator_symfony.ulid.symfony_ulid_identity_generator'
+```
+
+## Installation
+When all prerequisites are met, it's time to install the bundle package itself:
+
+```bash
+composer require gember/event-sourcing-symfony-bundle 
+```
+
+## Good to go! 
+Check the main package [gember/event-sourcing](https://github.com/GemberPHP/event-sourcing) or 
+the demo application [gember/example-event-sourcing-dcb](https://github.com/GemberPHP/example-event-sourcing-dcb) for examples.