# `DDD.Supervisor`
[🔗](https://github.com/blackuprise/vicander/blob/v0.1.1/lib/ddd/events/supervisor.ex#L1)

Starts what the framework needs at runtime, in the right order: the event bus, the handler
subscriptions, the outbox poller and the dead-letter handler. Put it in your supervision tree
after your repo:

    children = [
      MyApp.Repo,
      {DDD.Supervisor, handlers: [MyApp.Handlers.SendWelcome, MyApp.Projections.ListSummary]}
    ]

The repo is `config :vicander, repo: MyApp.Repo` (see `DDD.Config`).

## Options

  * `:handlers` - the event handlers and projections (modules that `use DDD.EventHandler` or
    `DDD.Projection`) to subscribe. They are subscribed before the poller starts, because an
    event with no subscribed handler counts as delivered. Default: none.
  * `:poller` - options for `DDD.Outbox.Poller` (`:interval_ms`, `:batch_size`, ...), or
    `false` for no poller and no dead-letter handler: what a test or a web-only node wants.
    Default: `[]`, which polls every 500 ms in batches of 100.
  * `:retention` - `[older_than_days: 30]` (and optionally `:every_ms`) to prune published
    events from the outbox on a timer (`DDD.Outbox.Retention`). Default: never prune.
  * `:repo` - another repo than the configured one
  * `:name` - the supervisor's name (default `DDD.Supervisor`)

If the event bus restarts, it forgets its subscriptions, so the supervisor restarts everything
after it (the subscriptions and the poller) too.

# `child_spec`

Returns a specification to start this module under a supervisor.

See `Supervisor`.

# `start_link`

```elixir
@spec start_link(keyword()) :: Supervisor.on_start()
```

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*Consult [api-reference.md](api-reference.md) for complete listing*