October 2022 Summaries

The article discusses the challenges of scaling WebSocket infrastructure and the key decisions involved in planning for it. It explains that while delivering live experiences through WebSockets is relatively easy, scaling them can be complex due to their stateful nature. Vertical scaling focuses on increasing the capacity of individual machines, whereas horizontal scaling introduces more machines to handle changes in demand. The article also covers some technical challenges and solutions related to load balancing and data synchronization. It emphasizes that while horizontal scaling is the only sustainable way to expand WebSocket capacity, it requires extra work in maintaining infrastructure.

WhatsApp's recent global outage highlights the importance of reliable realtime communication in today's world. As society increasingly relies on realtime experiences for work, study, and play, downtime can have significant financial and reputational costs. WhatsApp's $22bn realtime data architecture played a crucial role in its acquisition by Facebook due to its ability to deliver instant chat messages reliably even in areas with poor internet connection. To ensure the dependability of realtime experiences, organizations must consider various scenarios such as intermittent networks, globally distributed users, and maintaining stability and reliability. Leveraging infrastructure designed for these challenges can help avoid outages and provide a seamless user experience.

This post demonstrates how to use Azure Functions and Durable Functions to build a serverless workflow that publishes progress updates in real-time using Ably, a cloud-based pubsub service. The solution includes a Vue front-end for visualizing the workflow status and an Azure Static Web Apps hosting solution. The serverless workflow is implemented with Durable Functions, which allows writing workflows as code and enables stateful functions. The Ably realtime client is used to establish a WebSocket-based connection and subscribe to named events that correspond with the activity functions in the back-end. The front-end updates its UI based on these progress updates received from Ably.