SOA

A lot of Ruby and Rails developers can see writing on walls that tells them small, focused services are the future. Here is a quote from a well-known Ruby thoughtleader, promoting them on the popular microservice platform called Twitter dot com:

Microservices are great for turning method calls in to distributed computing problems

• Aaron Patterson on Aug. 9, 2018

I've helped many teams maintain old, slow, & confusing monolithic applications and it's taught me one thing: monolithic codebases become more complex over time. As a result, many companies have decided to build non-monolithic applications instead (these are called "services"; the better, more modern ones are called "microservices"). Applications built with services are initially much more difficult to create and operate, but they also tend to die sooner, which is the best known way to reduce code complexity.

But how do you write services and microservices in a monolithic language like Ruby? Up until now, writing services required JavaScript and AWS Lambda. But because I prefer to write Ruby and sometimes I work offline (AWS can't be used offline yet), I wrote the SOA gem.

The SOA gem is a drop-in replacement for Ruby's built-in method dispatch system. You can continue to call legacy methods like you always have alongside new service invocations registered with the SOA gem. It's the perfect companion for teams looking to make a more gradual transition to a services architecture without rewriting their entire decades-old application in JavaScript and AWS Lambda.

Installation

To install SOA, we use the command line program gem which communicates with the RubyGems.org microservice to download the necessary files:

gem install soa

And then, in your code, you can activate "SOA mode" in your Ruby interpreter like this

require "soa"

[Note that the SOA gem is only tested with C-Ruby. If you want to write services with JRuby, you'll need to wait for the release of a SOAP gem.]

Once required, the SOA gem will prepare your Ruby runtime to run services and microservices instead using our easy-to-use DSL.

Usage

To create a new microservice, we use the service method and specify a route path like so:

require "soa"

service "/api/user/:id" do |id|
  User.find(id)
end

In order to invoke a SOA microservice, we just call_service with the URL. The service is then looked up from the SOA Service Registry, the params are parsed, the service is invoked, and the results are returned.

user = call_service "/api/user/45"
puts user.id # => 45

It would barely be any easier to just define and call a legacy monolithic Ruby method!