For several years now, the Node.js ecosystem has been steadily shifting towards ES modules (ESM) as the preferred method for sharing and utilizing JavaScript code. While CommonJS has served the community well, ESM are rapidly gaining traction as they offer a standardized approach for creating JavaScript modules across all supported runtimes.

In part one of this series, we managed distributed state using GenServers. This provided a foundation for understanding some core concepts in distributed Phoenix applications. Now, we turn our focus to deployment and scaling strategies. As your application evolves to meet growing demands, knowing how to scale horizontally, maintain high availability, and monitor distributed components becomes crucial.

In this article, you'll learn about N+1 queries, how to detect them with AppSignal, and how to fix them to speed up your Django apps significantly. We'll start with the theoretical aspects and then move on to practical examples. The practical examples will mirror scenarios you might encounter in a production environment. Let's get started!

In the previous part of this series, we discovered how to create persistent connections in Rack in theory, but now we'll put what we learned into practice. The web has two formalized specifications for communication over a persistent connection: server-sent events (SSEs) and WebSockets. WebSockets are widely used and highly popular, but SSEs are far less well-known. Let's explore them first.

Unit tests are essential for increasing the test coverage of a backend application, ensuring its reliability, functionality, and robustness. Jest has become one of the most popular solutions when unit testing in Node, due to its intuitive API, zero-configuration philosophy, and flexible approach to code transpilation. In this guide, you will learn more about Jest, explore its features, and see it in action through a complete example. Become a Jest unit testing expert!

In the first part of this series, we set up a basic Rack app, learned how to process a request and send a response. In this post, we'll take over connections from Rack and hold persistent connections to enable pathways such as WebSockets. First, though, let's look at how an HTTP connection actually works.

When running tests, it's a great feeling to see dozens of green check marks indicating that a test suite is passing. It's especially gratifying after tackling a tricky bug or slogging through a tough feature. But those passing tests may be giving you a false sense of security. Often, bugs lurk in passing tests, undermining trust in the test suite and your application. Such tests can cause more harm than good, giving you a hearty pat on the back while hiding broken functionality.

Do you want the benefits of contract testing with much less effort? Are you convinced of the benefits of contract testing but think it’s just too difficult to roll out across your organization? You might worry that implementing Pact in your organization requires challenging changes to culture and process. In this article, I’ll show you a drastically simplified approach to contract testing that a single developer can bring online.

When developing an Elixir app, you'll often need to handle tasks in a way that does not interrupt the normal user request-response cycle. Tasks like sending emails are great examples of jobs that should be delegated to a capable background job processing service. In the Elixir ecosystem, Oban is one such background job processing library. In this article, we'll learn what Oban is, how it works, and how to instrument it using AppSignal.

Rack is the foundation for every popular Ruby web framework in existence. It standardizes an interface between a Ruby application and a web server. This mechanism allows us to pair any Rack-compliant web server (such as Puma, Unicorn, or Falcon) with any Rack-compliant web framework (like Rails, Sinatra, Roda, or Hanami). Separating the concerns like this is immensely powerful and provides a lot of flexibility. It does, however, also come with limitations.