Serverless Support for Socket.IO in Azure Web PubSub service

We’re excited to announce the public preview of Socket.IO serverless mode on the Azure Web PubSub service. This new mode eliminates the need for developers to maintain persistent connections on the application server, providing a more streamlined and scalable approach. In addition to the existing native mode, developers can now deploy Socket.IO applications to serverless environments using Azure Functions. It provides a stateless, highly scalable infrastructure that simplifies real-time feature development while reducing both operational costs and maintenance overhead.

What is Socket.IO serverless mode?

In traditional native mode, all Socket.IO clients connect directly to Azure Web PubSub. Developers don’t have to worry about whether there will be 100 million or 1 million concurrent users. This is a service that handles expansion or contraction according to changes in application users. However, the application server that handles the business logic must maintain a persistent connection to the service, which adds complexity compared to stateless HTTP services.

• Problems arise with persistent connections. Unlike HTTP services, which can recover quickly from downtime, servers with persistent connections require continuous uptime to manage client communications.
• Developer familiarity: Teams accustomed to stateless HTTP services may experience engineering difficulties due to persistent connections.
• Cost inefficiency: Maintaining persistent connections in low-frequency real-time messaging scenarios incurs unnecessary compute costs, such as managing the “ping-pong” heartbeats used by Socket.IO for connection loss detection.

As serverless computing gains popularity, developers are looking for ways to reduce the burden of server management while focusing on core business logic. Socket.IO serverless mode provides a flexible serverless deployment model, allowing real-time two-way communication between clients and servers without a persistent server connection.

In the new serverless mode, the Socket.IO server becomes stateless, pushing messages to clients through RESTful APIs and receiving messages through webhooks without compromising real-time communication between clients and servers. Socket.IO clients still have a persistent connection to the service, but developers can now focus on writing backend logic as stateless Azure Functions to simplify deployment and scaling.

This feature is not supported by default. Socket.IO library This is made possible through Azure Web PubSub for Socket.IO. This is part of our ongoing effort to improve the Socket.IO developer experience and simplify real-time application development.

Differences between native mode and serverless mode

Below is a typical architecture for native mode and serverless using Azure Web PubSub for Socket.IO. For more information on the differences, see: Feature Overview.

Differences between native mode and serverless in Web PubSub for Socket.IO

Getting started with Socket.IO serverless mode

Socket.IO serverless mode is ideal for scenarios that require lightweight, event-driven communication without the need for persistent backend connectivity. One of the best starting points is broadcast message to the Socket.IO client. Applications such as real-time sports scores, financial tickers, or real-time dashboards can greatly benefit from the scalability and cost efficiencies that serverless architecture provides.

To get started: “Post a message” Explore the tutorial and build a real-time stock index application using Python and Azure Functions.

In addition to one-way broadcasting two way Real-time communication between client and server remains the core feature of Socket.IO. our “Building a chat app” A step-by-step tutorial on how to implement two-way communication using Socket.IO serverless mode.

If you want a quick hands-on experience,quick start“ Learn how to build and deploy a chat application using Socket.IO serverless mode with identity-based authentication.