Send and receive Bitcoin transactions from your Phoenix or Plug-based Elixir application.

Txpost implements a standard for encoding and decoding Bitcoin transactions and other data in a concise binary format using CBOR. A number of modules following the Plug specification can easily be slotted in your Phoenix or Plug-based application's pipeline. An optional Router module is available, allowing you to implement routing logic for different types of transactions from a single endpoint.

• Receive Bitcoin transactions in a concise and efficient binary serialisation format
• Simple and flexible schema for sending Bitcoin data with other data parameters
• Send multiple transactions in a single request, or build streaming applications
• Sign and verify data payloads with ECDSA signatures

Txpost is an implementation of the following BRFC specifications. They describe a standard for serialising Bitcoin transactions and associated parameters, along with arbitrary meta data, in a concise binary format using CBOR:

• BRFC c9a2975b3d19 - CBOR Tx Payload specification
• BRFC 5b82a2ed7b16 - CBOR Tx Envelope specification

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

def deps do
  [
    {:txpost, "~> 0.1"}
  ]
end

Add Txpost.Parsers.CBOR to your endpoint's list of parsers.

plug Plug.Parsers,
  parsers: [
    :json,
    Txpost.Parsers.CBOR
  ]

Finally create any routes needed to handle transaction requests and add Txpost.Plug to the plug pipeline. For example, adding a route to a Phoenix router:

defmodule MyAppWeb.Router do
  use MyAppWeb, :router

  pipeline :tx_api do
    plug :accepts, ["cbor"]
    plug Txpost.Plug
  end

  scope "/tx" do
    pipe_through :tx_api
    post "/create", MyAppWeb.TxController, :create
  end
end

For detailed examples, refer to the full documentation.

The example above creates a single route passing all transactions to the same controller. You could create many routes for different transactions but in some applications it may be desirable to advertise a single endpoint to receive different types of transactions, each handled by different controllers. In this case Txpost.Router can be used to route transactions to different controllers, using any logic you need.

A tx router is a module that implements the Txpost.Router.handle_tx/2 callback.

defmodule MyApp.TxRouter do
  use Txpost.Router

  def handle_tx(conn, _params) do
    case get_req_meta(conn) do
      %{"type" => "article"} -> ArticleController.call(conn, :create)
      %{"type" => "image"} -> ImageController.call(conn, :create)
    end
  end
end

For more details, refer to the full documentation.

Txpost is open source and released under the Apache-2 License.

© Copyright 2021 Chronos Labs Ltd.