How does SignalR's scaleout dependencyResolver UseSqlServer work under the hood?

Question

Can anyone explain how signalR scaleout dependecyResolver UseSqlServer works.

1. How the Sql backplane works for SignalR applications (what goes on inside the sql server).
2. What is the architecture behind this component.
3. How does it queue and exchange messages.
4. What triggers to SignalR application to take action when there are changes in messaging queue table because the only implementation is what you see in the startup file and there's no other reference to it.
5. How does sql server messaging works without the service broker as mentioned in the MS documentation. https://learn.microsoft.com/en-us/aspnet/signalr/overview/performance/scaleout-with-sql-server message queue table startup.cs

There are lot of documentation on how to implement this but I need to know how this works inside to implement a different messaging system. I want to know how it exchanges messages in a cluster environment with multiple client applications. If anyone can explain that would be a great help. (a good diagram would help)