Hyperbuffs

Hyperbuffs is an Elixir library which strongly connects Phoenix to Protobuf definitions. Based on content negotiation from incoming requests, your controllers will seamlessly accept and respond in either JSON or Protobuf (you can even accept one and return another). The goal is that your controller definitions are strongly typed and you give clients the option of how the data is encoded.

To use Hyperbuffs, you will define your services with a desired RPC schema and connect those to your routes.

service ExampleService {
  rpc ping (Ping) returns (Pong) {
    option (google.api.http) = { post: "/ping" };
  }

  rpc status (StatusRequest) returns (StatusResponse) {
    option (google.api.http) = { get: "/status" };
  }
}

  service ExampleService, ExampleController

and your controllers will speak Protobuf:

  defmodule ExampleController do

    # Our actions now take a protobuf and return a protobuf
    @spec create(%Plug.Conn{}, %Defs.Ping{}) :: %Defs.Pong
    def create(_conn, %Defs.Ping{payload: payload}) do
      Defs.Pong.new(payload: payload)
    end
  end

Installation

If available in Hex, the package can be installed as:

1. Add hyperbuffs to your list of dependencies in mix.exs:

```elixir
def deps do
  [{:hyperbuffs, "~> 0.2.3"}]
end
```

2. Install protoc-gen-elixir from protobuf-ex:

```bash
cd ~
git clone https://github.com/hayesgm/protobuf-ex.git
cd protobuf-ex
mix escript.install
```

3. Add the following to your controllers, views and router:

`lib/my_app.ex`

```elixir
defmodule MyApp do
  # ...
  def controller do
    quote do
      use Phoenix.Controller, namespace: MyApp
      use Hyperbuffs.Controller # <- add this
      # ...
    end
  end

  def view do
    quote do
      use Phoenix.View, root: "lib/my_app/templates",
                        namespace: MyApp
      use Hyperbuffs.View # <- add this
      # ...
    end
  end

  def router do
    quote do
      use Phoenix.Router
      use Hyperbuffs.Router # <- add this
      # ...
    end
  end
end
```

*or*, add Hyperbuffs to each controller, view and router:

`page_controller.ex`

```elixir
def MyApp.PageController do
  use MyApp, :controller
  use Hyperbuffs.Controller

end
```

`page_view.ex`

```elixir
def MyApp.PageView do
  use MyApp, :view
  use Hyperbuffs.View

end
```

`router.ex`

```elixir
defmodule API.Router do
  use API, :router
  use Hyperbuffs.Router

end
```

4. Add protobufs mime type to your config:

`mix.exs`

defp deps do
  # ...
  {:mime, "~> 1.1"}
end

`config.exs`

```elixir
config :mime, :types, %{
  "application/x-protobuf" => ["proto"]
}
```

5. After adding that, you'll need to recompile mime:

```bash
mix deps.clean mime --build
mix deps.get
```

Getting Started

To use Hyperbuffs, you'll need to define some protobufs, add the service definitions to your routes, and then build your controller actions to take and return protobufs. The following walks through an example of this.

1. Add your protobuf definitions, e.g.:

`priv/proto/services.proto`

```elixir
syntax = "proto3";

import "annotations.proto";

package MyApp;

service PingService {
  rpc ping (Ping) returns (Pong) {
    option (google.api.http) = { get: "/ping" };
  }
}

message Ping {}
message Pong {
  uint32 timestamp = 1;
}
```

2. Generate your protobuf definitions (replace my_app with your app or package name)

mkdir ./lib/my_app/proto

protoc --proto_path="./priv/proto" --proto_path="./deps/hyperbuffs/priv/proto" --elixir_out="./lib/my_app/proto" ./priv/proto/**

Note: for an umbrella app, this would be:

protoc --proto_path="./priv/proto" --proto_path="../../deps/hyperbuffs/priv/proto" --elixir_out="./lib/my_app/proto" ./priv/proto/**

2. Add proto config to your desired routes:

```elixir
defmodule MyApp.Router do
  use MyApp, :router

  # Add this section if you want to allow protobuf inputs and responses
  pipeline :api do
    plug Plug.Parsers, parsers: [Plug.Parsers.Protobuf] # allows Protobuf input
    plug :accepts, ["json", "proto"] # allows for Protobuf response
  end

  scope "/" do
    pipe_through :api

    service MyApp.PingService, StatusController
  end
end
```

3. Build your actions in your controller:

```elixir
defmodule MyApp.StatusController do
  use MyApp, :controller

  @doc """
  Responds Pong to Ping.

  ## Examples

      iex> MyApp.StatusController.ping(%Plug.Conn{}, %MyApp.Ping{})
      %MyApp.Pong{timestamp: 1508114537}
  """
  @spec ping(Plug.Conn.t, %MyApp.Ping{}) :: %MyApp.Pong{}
  def ping(_conn, _ping) do
    MyApp.Pong.new(timestamp: :os.system_time(:seconds))
  end
end
```

4. Make sure you have a view for your controller:

```elixir
defmodule MyApp.StatusView do
  use MyApp, :view

end
```

5. That's all, run your app and view the endpoint.

```bash
$ mix phx.server
$ curl localhost:4000/ping
{"timestamp":1509119708}
```

Actions

Actions in Hyperbuffs try to follow an RPC model where you have a declared input and you return a declared output. Hyperbuffs will ensure that the input and output can be either JSON or Protobufs based on the Content-Type and Accept headers respectively.

That said, you still have access to conn and can render traditionally as well. Here's a few examples:

  @spec my_action(Plug.Conn.t, %{}) :: Plug.Conn.t | %{} | {Plug.Conn.t, %{}}
  def my_action(conn, req=%Defs.SomeReq{}) do
    # Return just a protobuf
    Defs.SomeResp.new(msg: "Hi #{req.name}")
  end

  def my_action(conn, req=%Defs.SomeReq{}) do
    # Return a conn and a protobuf to be rendered
    {
      conn |> put_resp_header("X-Req-Id", 5)
      Defs.SomeResp.new(msg: "Hi #{req.name}")
    }
  end

  def my_action(conn, req=%Defs.SomeReq{}) do
    # Return just a conn
    conn
    |> Hyperbuffs.View.render_proto Defs.SomeResp.new(msg: "Hi #{req.name}")
  end

Contributing

• For bugs, please open an issue with steps to reproduce.
• For smaller feature requests, please either create an issue, or fork and create a PR.
• For larger feature requests, please create an issue before starting work so we can discuss the design decisions.