# Service (Application) Configuration

`Ecotone` allows for customization of the core functionality as well as the [modules](https://docs.ecotone.tech/modules/overview).

## Extension Objects

Extension objects are configuration classes that tell Ecotone which provider we want to use. For example, when setting up asynchronous processing, we can choose different Message Channel implementations like RabbitMQ, Redis, or a database queue.

```php
class MyConfiguration
{
    #[ServiceContext]
    public function messageChannel()
    {
        return DbalBackedMessageChannelBuilder::create('async');
    }
}
```

{% hint style="success" %}
Extension Objects give us the flexibility to pick the best tool for our needs and easily switch providers later without changing any of our business logic. This way for example, we may use different extension objects for tests (e.g. In Memory Channel), and for Production (RabbitMQ/Kafka Channel).
{% endhint %}

## Module Configuration Extensions

Module Extensions are configurations for specific module, using class based configuration.\
\
Let's take a look on [Dbal](https://docs.ecotone.tech/modules/dbal-support) module configuration as example:

```php
class MyConfiguration // 1
{
    #[ServiceContext] // 2
    public function configuration() // 3
    {
        return DbalConfiguration::createWithDefaults() // 4
                ->withTransactionOnAsynchronousEndpoints(true)
                ->withTransactionOnCommandBus(true);
    }
}
```

1. Create your own class. You can name it whatever you like.
2. Add attribute to let `Ecotone` know that it should call this method to get the configuration.
3. Name the method whatever you like. You may return `array` of configurations or `specific configuration instance`.
4. Return specific configuration.

{% hint style="info" %}
Ecotone does not require specific class name or method name.\
All what is needed is `#[ServiceContext]` attribute.
{% endhint %}

### Environment Specific Configuration

If you want to enable different configuration for specific environment you may use of `Environment attribute`.

```php
class MyConfiguration
{
    #[ServiceContext]
    #[Environment(["dev", "prod"])]
    public function registerTransactions()
    {
        return DbalConfiguration::createWithDefaults()
                ->withTransactionOnAsynchronousEndpoints(true)
                ->withTransactionOnCommandBus(true);
    }
    
    #[ServiceContext]
    #[Environment(["test"])]
    public function registerTransactions()
    {
        return DbalConfiguration::createWithDefaults()
                ->withTransactionOnAsynchronousEndpoints(false)
                ->withTransactionOnCommandBus(false);
    }
}
```

Above will turn off transactions for `test` environment, keeping it however for `prod` and `dev`.

### Configuration Variables

You may access your configuration variables inside `ServiceContext` methods.

```php
class MyConfiguration
{
    #[ServiceContext]
    public function registerTransactions(#[ConfigurationVariable("database")] string $connectionDsn)
    {
        return Repository($connectionDsn);
    }
}
```

If you don't pass `ConfigurationVariable` attribute, it will be taken from parameter name.\
Below example is equal to above.

```php
class MyConfiguration
{
    #[ServiceContext]
    public function registerTransactions(string $database)
    {
        return Repository($database);
    }
}
```

{% hint style="warning" %}
Service Context is evaluated before container is dumped and cached. Therefore if you will change environment variables after your cache is dumped this won't be changed.\
\
This happens because Ecotone tries to maximalize configuration caching, in order to speed up run time execution and do no configuration at that time.
{% endhint %}

## Global Configuration

Some configuration are globally available, in that sense, they can be configured directly in related framework:

1. [Symfony Configuration](https://docs.ecotone.tech/modules/symfony/symfony-ddd-cqrs-event-sourcing#configuration)
2. [Laravel Configuration](https://docs.ecotone.tech/modules/laravel/laravel-ddd-cqrs-event-sourcing#configuration)
3. [Ecotone Lite](https://docs.ecotone.tech/modules/ecotone-lite#configuration)