Serverless SignalR Service - What do Azure Functions provide?

Question

Say I'm working with an Azure SignalR Service run in serverless mode to implement a chat application. I'm wondering why would we use Azure Functions for this. What do they provide us? Couldn't we just build the connection with the SignalR Service on our own directly? Or say, after we negotiate an access token with an Azure Function, why can't we just use the connection we build with that token to broadcast messages, rather than relying on an additional Azure Function to broadcast messages?

Answer 1

In the past, people used to couple SignalR in their own web api or mvc project. The problem was that when there was a need to scale, it wasn't possible to scale things separately. Also, when comes to SignalR, it's hard to work with sticky sessions for example. This is when they released Azure SignalR Service, a managed service that would implement the backplane pattern for you.

More info:

https://learn.microsoft.com/en-us/aspnet/signalr/overview/performance/scaleout-in-signalr

The last piece would be to separate the real time bi-directional communication from the webapi / mvc project. They added Azure Functions as it's a light weight and easier to scale when comparating with webapi / mvc.

why can't we just use the connection we build with that token to broadcast messages, rather than relying on an additional Azure Function to broadcast messages

A: It's because the function is not being executed 100% time.