Implementing Real-time User Online Count with Phoenix Presence

The blog post explains how to add a real-time live reader count feature to a blog using the Phoenix Presence module within a Phoenix LiveView application. Florian Arens shares his experience of redesigning his website and adding a real-time user counter to blog posts. He describes this counter as an interactive element that increases and decreases as users come and go. The article delves into the Phoenix LiveView lifecycle, the use of Phoenix PubSub for real-time messaging, and the easy integration of Phoenix Presence to track user presence with metadata. It also touches upon the lightweight and concurrent nature of Elixir processes, making them suitable for handling many connections such as individual LiveView client sessions. The article includes code snippets that illustrate the implementation process, from subscribing to topics to tracking and displaying online user counts in real-time.