Implementing a custom backplane

This recipe will be slightly different from the other ones used in this chapter. We'll not show you any fancy application; instead, we will demonstrate how we can build a brand new custom backplane and hook it into SignalR's pipeline.

The idea of a backplane is to support SignalR's broadcasting feature in scenarios where we need to scale out the broadcast over multiple servers. We've already described the backplanes made available out of the box with SignalR, but here we show you how we can create our own backplane to distribute messages on top of a broadcasting system that we should know very well by now SignalR itself!

As explained in Chapter 7, Analyzing Advanced Scenarios, a backplane has to support several instances of the same SignalR server, and it has to redistribute every outgoing message from one of those instances to every server that it supports. This mechanism makes message broadcasting work well even behind a load balancer, regardless of which...