Blog article

If you’re considering migrating your Ruby on Rails application to Elixir for its advantages such as performance, concurrency, and fault-tolerance, you might have a lot of questions. However, the transition can be a smooth one if you approach it systematically and consider a few critical factors.

The purpose of this post is to highlight a few key aspects that you should take into consideration when migrating your existing Ruby on Rails code to Elixir. So let’s jump straight into it!

Understanding the Paradigm Shift

Perhaps the most important consideration, and the one we’ve seen teams struggle the most, is the paradigm shift from Object Oriented Programming (OOP) to Functional Programming (FP). As your probably already know, Ruby is an OOP language whereas Elixir is a functional one.

This means the way you structure your applications, handle state, and deal with data will be different. In functional programming, you’ll favor pure functions without side effects, and data is immutable. In contrast, OOP uses classes, objects, and mutable state. Understanding this shift and its implications is crucial to successfully transition from Ruby on Rails to Elixir.

Before starting the migration, you should spend some time learning about functional programming concepts. There are a bunch of great resources to get started with Elixir, so go ahead and make sure you understand the new paradigm first.

Phoenix Web Framework

If coming from Ruby you’re likely familiar with Rails, and how it makes a lot of things easier when building for the web. In a similar fashion, Phoenix is the most popular web framework in the Elixir ecosystem, since it offers similar benefits in terms of productivity and convention over configuration. In addition, it also leverages the features of the Elixir language and the Erlang VM to offer higher performance and more robustness, especially for real-time applications.

You need to understand how Phoenix differs from Rails though. For example, Phoenix doesn’t support ActiveRecord-style ORM. Instead, it uses Ecto, a database wrapper and query generator with a different philosophy. Understanding Ecto’s advantages, like data mapping and change tracking, will be important during your migration since your Model layer of MVC will be drastically different on Elixir.

Concurrency and Error Handling

Elixir, running on the Erlang VM, is known for its lightweight process model that makes concurrent programming a breeze. This is a stark contrast to Ruby, which has a Global Interpreter Lock (GIL) preventing your code to make use of more than one CPU core at a time.

Understanding how Elixir handles concurrency will allow you to architect your applications in a way that you can take full advantage of this feature. You can handle more users with fewer resources, which is a significant win for web applications.

Similarly, error handling in Elixir is different due to its “let it crash” philosophy. In Elixir, you’re expected to let processes that encounter errors die and have supervisors restart them, rather than trying to handle every possible error. This approach simplifies code and makes systems more resilient.

Real-Time Web Application Support

Real-time features are increasingly becoming essential components of web applications today. Both Ruby on Rails and Elixir with Phoenix have ways to handle these needs, but their approaches differ significantly.

On one hand, Rails uses Action Cable for handling WebSockets, allowing for real-time features like chat, notifications, and live updates. However, it’s worth noting that this can be resource-intensive and might struggle to scale under high loads due to Ruby’s limitations in handling concurrent connections.

On the other hand, Elixir with Phoenix shines in this area with a feature called Channels. Built on top of Erlang’s lightweight process model, Phoenix Channels allow for a vast number of concurrent connections, delivering real-time functionalities with high performance and efficient resource utilization.

Additionally, you can take advantage of LiveView. It enables real-time, server-rendered HTML without writing any JavaScript. This feature can simplify the development process and help build interactive, real-time applications faster.

If your Rails application heavily uses real-time features or is expected to handle a significant number of concurrent connections, migrating to Elixir and Phoenix could bring substantial benefits in terms of performance and scalability.

Background Processing

Background processing is a fundamental part of many web applications. In Ruby on Rails, this typically involves using a separate service for background jobs using gems like Sidekiq, DelayedJob, or Resque. These libraries make use of multi-threading and Redis to process jobs asynchronously.

When transitioning to Elixir, it’s important to understand that the language, running on the Erlang VM, has different mechanisms for background processing. That means it’s not mandatory to rely on separate services or libraries, given that Elixir applications can use OTP (Open Telecom Platform) principles to create lightweight processes for asynchronous tasks. For example, background tasks in Elixir are just another process. This can significantly simplify your system architecture as you don’t need a separate service for job processing.

This ability to handle concurrency within the application itself is a significant advantage Elixir holds over many other programming languages and is a key factor to consider when migrating from Ruby to Elixir.

Code Conversion and Interoperability

Lastly, a practical consideration is the actual process of converting your Ruby code to Elixir. This isn’t always straightforward, as the languages are different and some things simply don’t translate directly.

It’s often a good idea to not attempt a “big bang” conversion of your entire application at once. Instead, consider an iterative approach, converting and implementing parts of your application one at a time. This approach will allow you to gradually get used to Elixir and Phoenix, and reduce the risks of introducing bugs during the migration.

Keep in mind that there’s also the option for interoperability. For a smoother transition, you could have your Ruby and Elixir applications communicate, say via HTTP APIs or message queues, allowing you to gradually shift functionality over to Elixir.

Remember, the aim of this migration is not just to convert Ruby code into Elixir syntax, but to leverage the strengths of Elixir and Phoenix and build more robust, scalable, and efficient applications.

Closing thoughts

Migrating applications from one language to another is a major endeavor that can bring significant benefits, like improvements in performance, scalability, and robustness. However, it’s also a journey of learning and exploration, and the transition needs to be planned and executed thoughtfully.

Keep in mind that migrations are never a one-size-fits-all process. But, with careful consideration and a methodical approach, you’ll be well on your way to leveraging the powerful capabilities of Elixir.

And, if you’d like some additional help on the process don’t hesitate to reach out! Having a number of migrations on our belt already, we can certainly bring our experience to the table and help you!