What is Azure SignalR? #

Azure SignalR Service is a managed service offered by Microsoft Azure that facilitates the integration of real-time communication features into web and mobile applications. Leveraging the SignalR library, it enables bidirectional, instant messaging between clients and servers. The service is designed to simplify the development of applications that require real-time updates, such as chat applications, multiplayer games, and collaborative tools, by handling the underlying infrastructure complexities. Azure SignalR Service also excels in scalability, allowing it to automatically adjust to varying workloads and ensuring that applications remain responsive during high traffic periods.

This service supports a wide range of client platforms, making it suitable for cross-platform development, including web, mobile, desktop, and IoT applications. It offers robust connection management capabilities, simplifying user presence tracking and connection handling, and incorporates security features to safeguard real-time communication. Moreover, Azure SignalR Service can be seamlessly integrated with other Azure services and third-party applications, making it a versatile choice for developers seeking to incorporate real-time functionality into their applications while taking advantage of Azure’s cloud infrastructure.

Why it is important to load balance Azure SignalR? #

Load balancing an Azure SignalR Service is important for several reasons. First and foremost, it ensures high availability and reliability of real-time communication within your applications. By distributing incoming connections and traffic across multiple instances of the Azure SignalR Service, load balancing prevents any single instance from becoming overwhelmed, reducing the risk of service disruptions due to overloads or potential failures. This is especially crucial for applications that rely on real-time updates, as downtime or poor performance can result in a negative user experience.

Secondly, load balancing Azure SignalR Service helps optimize performance and scalability. Azure SignalR Service is designed to automatically scale based on demand, and using load balancers can enhance this scalability. When traffic increases, the load balancer can route connections to additional service instances, ensuring that your application remains responsive during traffic spikes. Conversely, it can also distribute traffic away from underutilized instances, helping to save on costs. Overall, load balancing Azure SignalR Service is a fundamental practice for maintaining consistent performance, high availability, and efficient resource utilization in real-time communication applications hosted on the Azure platform.

Configure Sticky Sessions or Session Affinity in the load balancer #

In RELIANOID Load Balancer, configuring sticky sessions for SignalR is very simple. If a HTTP farm is used, Persistence by IP Client Address can be enabled in the SignalR service. Also, Cookie Insert can be used for a more elaborated affinity where the load balancer created a cookier per user.

For L4 farms, can be also configured for sticky session by configuring persistence by Source IP.

All types of persistence it comes with a timeout that indicates the expiration of such session if the client is not requesting the virtual service anymore. Such value will depend on the real application usability, but values from 60 to 120 seconds could be generally a good option.