# RabbitMQStream

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Zero dependencies Elixir Client for [RabbitMQ Streams Protocol](https://www.rabbitmq.com/streams.html).

## Usage

### Subscribing to stream

First you define a connection

```elixir
defmodule MyApp.MyConnection do
  use RabbitMQStream.Connection
end
```

You then can declare a subscriber module with the `RabbitMQStream.Subscriber`:

```elixir
defmodule MyApp.MySubscriber do
  use RabbitMQStream.Subscriber,
    connection: MyApp.MyConnection,
    stream_name: "my_stream",
    initial_offset: :first

  @impl true
  def handle_chunk(%RabbitMQStream.OsirisChunk{}=_chunk, _subscriber) do
    :ok
  end
end
```

Or you could manually subscribe to the stream with

```elixir
{:ok, _subscription_id} = MyApp.MyConnection.subscribe("stream-01", self(), :next, 999)
```

The caller process will start receiving messages with the format `{:chunk, %RabbitMQStream.OsirisChunk{} = chunk}`

```elixir
def handle_info({:chunk, %RabbitMQStream.OsirisChunk{} = chunk}, state) do
  # do something with message
  {:noreply, state}
end
```

You can take a look at an example Subscriber GenServer at the [Subscribing Documentation](guides/tutorial/subscribing.md).

### Publishing to stream

RabbitMQ Streams protocol needs a static `:reference_name` per publisher. This is used to prevent message duplication. For this reason, each stream needs, for now, a static module to publish messages, which keeps track of its own `publishing_id`.

You can define a `Publisher` module like this:

```elixir
defmodule MyApp.MyPublisher do
  use RabbitMQStream.Publisher,
    stream: "stream-01",
    connection: MyApp.MyConnection
end
```

Then you can publish messages to the stream:

```elixir
MyApp.MyPublisher.publish("Hello World")
```

## Installation

The package can be installed by adding `rabbitmq_stream` to your list of dependencies in `mix.exs`:

```elixir
def deps do
  [
    {:rabbitmq_stream, "~> 0.3.0"},
    # ...
  ]
end
```

## Configuration

The configuration for the connection can be set in your `config.exs` file:

```elixir
config :rabbitmq_stream, MyApp.MyConnection,
  username: "guest",
  password: "guest"
  # ...
end

```

For more information, check the [documentation](https://hexdocs.pm/rabbitmq_stream/).