Add example and more detailed description for GenRMQ.Processor (#146)

README.md

@@ -18,7 +18,7 @@ The project currently provides the following functionality:
 
 - `GenRMQ.Consumer` - a behaviour for implementing RabbitMQ consumers
 - `GenRMQ.Publisher` - a behaviour for implementing RabbitMQ publishers
-- `GenRMQ.Processor` - a behaviour for implementing RabbitMQ message processors
+- `GenRMQ.Processor` - a behaviour for implementing RabbitMQ message processors, this is useful to separate out business logic from your consumer
 - `GenRMQ.RabbitCase` - test utilities for RabbitMQ ([example usage][rabbit_case_example])
 
 ## Installation
@@ -35,7 +35,7 @@ Please check [how to migrate to gen_rmq `1.0.0`][migrating_to_100] from previous
 
 ## Examples
 
-More thorough examples for using `GenRMQ.Consumer` and `GenRMQ.Publisher` can be found in the [examples][examples] directory.
+More thorough examples for using `GenRMQ.Consumer`, `GenRMQ.Publisher`, and `GenRMQ.Processor` can be found in the [examples][examples] directory.
 
 ### Consumer
 
@@ -197,7 +197,7 @@ Are you using `gen_rmq` in production? Please let us know, we are curious!
 
 The MIT License (MIT)
 
-Copyright (c) 2018 - 2019 Meltwater Inc. [http://underthehood.meltwater.com/][underthehood]
+Copyright (c) 2018 - 2020 Meltwater Inc. [http://underthehood.meltwater.com/][underthehood]
 
 [behaviours]: https://hexdocs.pm/elixir/behaviours.html
 [amqp]: https://github.com/pma/amqp

examples/processor.ex

@@ -0,0 +1,24 @@
+defmodule ExampleProcessor do
+  @moduledoc """
+  Example GenRMQ.Processor implementation
+
+  Sample usage:
+  ```
+  iex -S mix
+  iex(1)> ExampleProcessor.process(%GenRMQ.Message{payload: "Hello", attributes: [], state: %{}})
+  Received message: %GenRMQ.Message{attributes: [], payload: "Hello", state: %{}}
+  iex(2)> ExampleProcessor.process(%GenRMQ.Message{payload: "error", attributes: [], state: %{}})
+  ** (RuntimeError) Exception triggered by message
+    (gen_rmq) examples/processor.ex:18: ExampleProcessor.process/1
+  ```
+  """
+
+  @behaviour GenRMQ.Processor
+
+  def process(%GenRMQ.Message{payload: "error"}), do: raise("Exception triggered by message")
+
+  def process(%GenRMQ.Message{} = message) do
+    IO.puts("Received message: #{inspect(message)}")
+    :ok
+  end
+end

lib/processor.ex

@@ -1,6 +1,10 @@
 defmodule GenRMQ.Processor do
   @moduledoc """
-  Defines functions to implement by any AMQP processor
+  Behaviour module for implementing a RabbitMQ message processor.
+
+  A message processor is typically used to separate out business logic from a consumer,
+  to let the consumer only deal with RabbitMQ specifics.
   """
+
   @callback process(message :: %GenRMQ.Message{}) :: :ok | {:error, term}
 end