Broadway Framework Elixir

Broadway is a flexible and efficient data processing and event-driven framework built with Elixir.

It allows developers to build concurrent and fault-tolerant data processing pipelines in a declarative manner. Broadway is highly scalable and can handle large volumes of data while ensuring low latency and high throughput.

In this tutorial, we will explore the history, features, and examples of using Broadway in Elixir applications. We will cover the basic concepts, demonstrate some of the key features with code snippets, and discuss the output of each example.

History of Broadway

Broadway was introduced by Plataformatec, a software consultancy company specializing in Elixir and Ruby. The framework was initially released in 2019 and has gained popularity in the Elixir community due to its simplicity and scalability.

Key Features of Broadway

1. Fault-tolerant and reliable processing

Broadway provides fault-tolerant processing by handling failures and retries transparently. It ensures that no data is lost during processing, even in the presence of failures. Failed events can be retried or skipped based on custom logic defined by the developer.

2. High concurrency and scalability

Broadway leverages Elixir's lightweight processes and the actor model to achieve high concurrency and scalability. It allows developers to process multiple events concurrently, enabling efficient utilization of system resources.

3. Backpressure handling

Broadway automatically handles backpressure to prevent overwhelming downstream systems. It adjusts the processing rate based on the capacity of the system to ensure efficient and reliable data processing.

4. Declarative configuration

Broadway allows developers to define data processing pipelines using a declarative configuration. It provides a clean and expressive syntax for defining stages, data sources, and processors, making it easy to understand and maintain complex pipelines.

5. Built-in data source connectors

Broadway provides built-in connectors for various data sources such as RabbitMQ, Kafka, and GenStage. These connectors simplify the integration of Broadway with external systems and enable seamless data ingestion.

Examples of Broadway Features

Example 1: Creating a Simple Broadway Pipeline

Let's start with a simple example of creating a Broadway pipeline that processes events from a data source.

defmodule MyApp.Pipeline do
  use Broadway

  def start_link(_opts) do
    Broadway.start_link(__MODULE__,
      name: __MODULE__,
      processors: [
        default: [name: MyApp.Processor]
      ]
    )
  end
end

defmodule MyApp.Processor do
  def handle_message(_, event, _) do
    # Process the event
    IO.inspect(event)

    {:ok, event}
  end
end

In this example, we define a Broadway pipeline using the Broadway macro. The pipeline consists of a single processor module MyApp.Processor that handles each event. The handle_message/3 function is called for each event, where we can perform any desired processing logic. In this case, we simply inspect the event and return it.

To start the pipeline, we call MyApp.Pipeline.start_link/1.

Example 2: Fault-tolerant Processing

Broadway provides built-in fault-tolerant processing capabilities. Let's modify our previous example to handle failures and retries.

defmodule MyApp.Processor do
  def handle_message(_, event, _) do
    case process_event(event) do
      {:ok, result} -> {:ok, result}
      {:error, reason} -> {:retry, reason}
    end
  end

  defp process_event(event) do
    # Process the event and handle potential failures
    if some_condition do
      {:ok, processed_event}
    else
      {:error, "Failed to process event"}
    end
  end
end

In this example, we handle failures by returning {:retry, reason} if the event processing fails. Broadway will automatically retry the event based on the configured retry strategy. If an event fails multiple times, it can be skipped or sent to a dead-letter queue for manual inspection.

Example 3: Backpressure Handling

Broadway automatically handles backpressure to prevent overwhelming downstream systems. Let's see how it works in practice.

defmodule MyApp.Processor do
  def handle_message(_, event, _) do
    # Simulate a slow processing operation
    Process.sleep(1000)

    IO.inspect(event)

    {:ok, event}
  end
end

In this example, we introduce a sleep operation to simulate a slow processing operation. Broadway automatically adjusts the processing rate based on the capacity of the system and the downstream systems, ensuring that the pipeline does not overwhelm the system with excessive events.

Conclusion

Broadway is a powerful framework for building scalable and fault-tolerant data processing pipelines in Elixir. It provides a declarative syntax, fault-tolerant processing, high concurrency, backpressure handling, and built-in data source connectors. By leveraging Broadway, developers can easily build efficient and reliable data processing systems.

To learn more about Broadway and explore advanced features, you can visit the official documentation and examples on the official Broadway website.