Configuration

Aggregate

A path must be specified for Event Sourcing to know where to look for your aggregates. If you want you can use glob patterns to specify multiple paths.

return [
    'aggregates' => [app_path()],
];

Or use an array to specify multiple paths.

return [
    'aggregates' => [
        app_path() . 'src/Hotel/Domain',
        app_path() . 'src/Room/Domain',
    ],
];

Events

A path must be specified for Event Sourcing to know where to look for your events. If you want you can use glob patterns to specify multiple paths.

return [
    'events' => [app_path()],
];

Or use an array to specify multiple paths.

return [
    'events' => [
        app_path() . 'src/Hotel/Domain/Event',
        app_path() . 'src/Room/Domain/Event',
    ],
];

Custom Headers

If you want to implement custom headers for your application, you must specify the paths to look for those headers. If you want you can use glob patterns to specify multiple paths.

return [
    'headers' => [app_path()],
];

Or use an array to specify multiple paths.

return [
    'headers' => [
        app_path() . 'src/Hotel/Domain/Header',
        app_path() . 'src/Room/Domain/Header',
    ],
];

Connection

You have to specify the connection url to the event store.

return [
    'connection' => [
        'url' => env('EVENT_SOURCING_DB_URL'),
    ],
];

Connection for Projections

Per default, our event sourcing connection is not available to use in your application. But you can create a dedicated connection that you can use for your projections.

return [
    'connection' => [
        'url' => env('EVENT_SOURCING_DB_URL'),
        'provide_dedicated_connection' => true,
    ],
];

use Doctrine\DBAL\Connection;
use Patchlevel\LaravelEventSourcing\Attribute\ProjectionConnection;

final class MyService
{
    public function __construct(
        #[ProjectionConnection]
        private readonly Connection $connection,
    ) {
    }
}

Store

The store and schema is configurable.

Change Store type

You can change the store type of the event store.

return [
    'store' => ['type' => 'dbal_stream'],
];

Following store types are available:

• dbal_aggregate default (deprecated)
• dbal_stream recommended
• in_memory
• custom

Change table Name

You can change the table name of the event store.

return [
    'store' => [
        'type' => 'dbal_stream',
        'options' => ['table_name' => 'my_event_store'],
    ],
];

Read Only Mode

For dbal_aggregate and dbal_stream store types you can activate the read only mode. Readings are possible, but if you try to write, an exception StoreIsReadOnly is thrown.

return [
    'store' => [
        'type' => 'dbal_stream',
        'readonly' => true,
    ],
];

Data Migration

If you want to migrate from your current store to a new store, you can use the following configuration. This registers a new store and a new cli command event-sourcing:store:migrate. You can define translators to translate the old events to the new store. Here is an example for a migration from dbal_aggregate to dbal_stream.

use Patchlevel\EventSourcing\Message\Translator\AggregateToStreamHeaderTranslator;

return [
    'store' => [
        'type' => 'dbal_aggregate',
        'readonly' => true,
        'options' => ['table_name' => 'old_store'],
        'migrate_to_new_store' => [
            'enabled' => true,
            'type' => 'dbal_stream',
            'options' => ['table_name' => 'my_stream_store'],
            'translators' => [
                AggregateToStreamHeaderTranslator::class,
            ],
        ],
    ],
];

Subscription

Store

You can change where the subscription engine stores its necessary information about the subscription. Default is dbal, which means it stores it in the same DB that is used by the dbal event store.

Otherwise you can choose between the following stores:

• dbal default
• in_memory
• static_in_memory
• custom

return [
    'subscription' => [
        'store' => [
            'type' => 'custom', // default is 'dbal'
            'service' => 'my_subscription_store',
            'options' => ['table_name' => 'my_subscription_store'],
        ],
    ],
];

Catch Up

If aggregates are used in the processors and new events are generated there, then they are not part of the current subscription engine run and will only be processed during the next run or boot. This is usually not a problem in prod environment because a worker is used and these events will be processed at some point. But in testing it is not so easy. For this reason, you can activate the catch_up option. For local dev this is also very handy.

return [
    'subscription' => [
        'catch_up' => [
            'enabled' => true,
            'limit' => null, // define a limit to catch up only a limited number of events
        ],
    ],
];

Throw on Error

You can activate the throw_on_error option to throw an exception if a subscription engine run has an error. This is useful for testing and development to get direct feedback if something is wrong.

return [
    'subscription' => ['throw_on_error' => true],
];

Run After Aggregate Save

If you want to run the subscription engine after an aggregate is saved, you can activate this option. This is useful for testing and development, so you don't have to run a worker to process the events.

return [
    'subscription' => [
        'run_after_aggregate_save' => [
            'enabled' => true,
            'ids' => null, // limit to specific subscriptions ids
            'groups' => null, // limit to specific subscriptions groups
            'limit' => null, // limit how many events should be processed
        ],
    ],
];

Auto Setup

If you want to automatically setup the subscription engine, you can activate this option. This is useful for development, so you don't have to setup the subscription engine manually.

return [
    'subscription' => [
        'auto_setup' => [
            'enabled' => true,
            'ids' => null, // limit to specific subscriptions ids
            'groups' => null, // limit to specific subscriptions groups
        ],
    ],
];

Rebuild After File Change

If you want to rebuild the subscription engine after a file change, you can activate this option. This is also useful for development, so you don't have to rebuild the projections manually.

return [
    'subscription' => [
        'rebuild_after_file_change' => ['enabled' => true],
    ],
];

Gap Detection

Depending on the database you are using for the eventstore it may be happening that your subscriptions are skipping some events. This is due to how auto-increments work in these databases in combination with e.g. longer open transactions. Even when not working with longer open transactions, this may occur if load is high on the database. We already have a locking mechanism in place to prevent this behavior which throttles write speed. Gap Detection operates differently, it checks if a gap between the last message handled and the current message is present. If so it waits a reasonable amount of time and re-fetches the message. This results in slower updates for the subscriptions but creates more resilience.

return [
    'subscription' => [
        'gap_detection' => ['enabled' => true],
    ],
];

You can also define how often the gap detection should re-check the gap and how long it should wait, in this example we instantly retry the first time, then we wait 500ms and after that we check a last time after 1 second.

return [
    'subscription' => [
        'gap_detection' => [
            'enabled' => true,
            'retries_in_ms' => [0, 5, 50, 500],
        ],
    ],
];

Another config option is to define the detection window. The option defines the timeframe from now if we should check for a gap. It's defined as an DateInterval so you need to provide a valid string for it.

return [
    'subscription' => [
        'gap_detection' => [
            'enabled' => true,
            'detection_window' => 'PT5M',
        ],
    ],
];

Command Bus

You can enable the command bus integration to use your aggregates as command handlers.

return [
    'subscription' => [
        'command_bus' => ['enabled' => true],
    ],
];

For now, we do not provide a laravel/queue integration, but we are open for suggestions.

Instant Retry

You can define the default instant retry configuration for the command bus. This will be used if you don't define a retry configuration for a specific command.

use Patchlevel\EventSourcing\Repository\AggregateOutdated;

return [
    'subscription' => [
        'command_bus' => [
            'enabled' => true,
            'instant_retry' => [
                'default_max_retries' => 3,
                'default_exceptions' => [
                    AggregateOutdated::class,
                ],
            ],
        ],
    ],
];

Query Bus

You can enable the query bus integration to use queries to retrieve data from your system.

return [
    'subscription' => [
        'query_bus' => ['enabled' => true],
    ],
];

For now, we do not provide a laravel/queue integration, but we are open for suggestions.

Event Bus

You can enable the event bus to listen for events and messages synchronously. The subscription engine is highly recommended to use instead of the event bus.

return [
    'subscription' => [
        'event_bus' => ['enabled' => true],
    ],
];

Snapshot

You only need to tell the aggregate that it should use this snapshot store.

namespace App\Profile\Domain;

use Patchlevel\EventSourcing\Aggregate\BasicAggregateRoot;
use Patchlevel\EventSourcing\Attribute\Aggregate;
use Patchlevel\EventSourcing\Attribute\Snapshot;

#[Aggregate(name: 'profile')]
#[Snapshot('default')]
final class Profile extends BasicAggregateRoot
{
    // ...
}

Cryptography

You can use the library to encrypt and decrypt personal data. For this you need to enable the crypto shredding.

return [
    'cryptography' => [
        'enabled' => true,
        'use_encrypted_field_name' => true,
        'fallback_to_field_name' => false,
    ],
];

If you want to use another algorithm, you can specify this here:

return [
    'cryptography' => [
        'enabled' => true,
        'algorithm' => 'aes256',
    ],
];

Clock

The clock is used to return the current time as DateTimeImmutable.

Freeze Clock

You can freeze the clock for testing purposes:

return [
    'clock' => ['freeze' => '2020-01-01 22:00:00'],
];

PSR-20

You can also use your own implementation of your choice. They only have to implement the interface of the psr-20. You can then specify this service here:

return [
    'clock' => ['service' => 'my_own_clock_service_id'],
];