AMQP RPC Client/Server templates

Warning! POC quality!

Goals

Reduce boilerplate
Handle reconnects
Messages housekeeping
Logging
Monitoring
Use fuse
Content negotiation

Fuse

Fuse helps reduce latency when something goes wrong with RabbitMQ or RPC server side by breaking circuit and returning immideately. Fuse can be configured via fuse_name and fuse_opts keys. We trying to maintain sensible default for those.

Monitoring/Instrumenting

Clients can be instrumented using built-in metrics plugins. Currenly implemented

ETS-backed plugin (default)
Prometheus plugin.

Example

Below is ‘classic’ RPC example from RabbitMQ tutorials
rewritten using amqp_rpc:

Client:

defmodule Fibonacci do
  use AMQP.RPC.Client, [exchange: "",
                        queue: "rpc_queue"]
  def fib(n, timeout \\ @timeout) do
    rpc(%{command_name: "fib",
          args: n}, timeout)
  end
end

Server:

defmodule FibonacciServer do
  use AMQP.RPC.Server, [exchange: "",
                        queue: "rpc_queue",
                        commands: [:fib]]
  ## adapted from https://gist.github.com/stevedowney/2f910bd3d72678b4cf99
  def fib(0), do: 0
  def fib(n)
  when is_number(n) and n > 0,
    do: fib(n, 1, 0, 1)
  def fib(_), do: [error: "positive integers only"]
  def fib(n, m, _prev_fib, current_fib)
  when n == m,
    do: current_fib
  def fib(n, m, prev_fib, current_fib),
    do: fib(n, m+1, current_fib, prev_fib + current_fib)
end

Installation

Available in Hex, the package can be installed as:

Add amqp_rpc to your list of dependencies in mix.exs:
```
def deps do
 [{:amqp_rpc, "~> 0.0.7"}]
end
```

Ensure amqp_rpc is started before your application:

def application do
 [applications: [:amqp_rpc]]
end