MMonad

Messaging Monad, backed by 0MQ

MMonad provides a DSL for sending and receiving messages through 0MQ sockets.

1. 0MQ

• libzmq ZeroMQ core engine in C++, implements ZMTP/3.0 https://github.com/zeromq/libzmq
• czmq High-level C binding for ØMQ https://github.com/zeromq/czmq

2. Ruby

• 2.4.2 minimum supported. rbenv is the recommended Ruby install tool

3. Docker https://store.docker.com/search?offering=community&type=edition (optional, but highly recommended)

Users with a Docker installation will find the first two requirements met by using the published image layer at https://hub.docker.com/r/jprime/mmonad

User contributions are welcome and subject to the contribution and code of conduct guideliness. All code made available under AGPL-3.0.

MMonad makes two interfaces available to Ruby programmers: (1) the MMonad::Agent and (2) the MMonad::Client. These interfaces are provided as modules. Users extend a class with the chosen interface, supplying specific behaviors via the DSL.

DSL for data-processing nodes:

• MMonad::Agent
  • .socket specifies underlying socket or address for networking
  • .pattern specifies the 0MQ socket pattern for message delivery
  • .process specifies the programmer's steps for message ingestion and/or transformation
  • .exceptions specifies the programmer's custom error handling behavior
  • .run initiates the data-processing loop with the above DSL specifications, blocking on the thread

DSL for data-passing nodes:

• MMonad::Client
  • .endpoint specifies the underlying socket or address for networking
  • .pattern specifies the 0MQ socket pattern for message passing
  • .response specifies the programmer's steps for response parsing
  • .timeout specifies how long to wait on a socket for a response
  • .message accepts a Hash to pass along the 0MQ socket as data

The structure of the Mmonad DSL has been designed such that projects using the gem need only focus on their specific business logic, leaving all the generic 0MQ pattern implementation to this project. The examples below demonstrate how projects using mmonad focus on their own business logic.

Each example below has a corresponding feature test. See the feature test directory for basic testing strategies. See the MMonad::Pattern::LIBRARY for currently supported patterns.

class MyAgent
  extend MMonad::Agent

  socket 'tcp://0.0.0.0:5678'
  pattern :reply

  process do |message|
    puts "got a message: #{message}"

    { business_reply: "Business is great!" }
  end

  exceptions do |exception|
    { business_reply: "This is not good for business: #{exception}" }
  end
end

class MyClient
  extend MMonad::Client

  endpoint 'tcp://localhost:5678'
  pattern :request

  timeout 5 # seconds

  response do |message|
    puts "got a response: #{message}"
  end
end

Thread.new { MyAgent.run }

MyClient << { customer_message: "How is business?" }

#=> got a message: { "customer_message" => "How is business?" }
#=> got a response: { "business_reply" => "Business is great!" }