11. Server Sent Events (SSE)

Server Sent Events (SSE) is a technology that allows a server to communicate directly with a connected client. SSE can be more efficient in certain circumstances, as the client will only request to retrieve information when the server notifies the client of a change. However, one drawback to SSE is that clients need to remain connected, taking up resources like memory and CPU.

With HTMX and ASP.NET Core, it is pretty straightforward to use SSE events. This project uses the NuGet package Lib.AspNetCore.ServerSentEvents to propagate changes to all connected clients. To see the service in action, look at the file Models/ServerEventsWorker and the Razor page 11_ServerEvents.

As you may have noticed, the number below continues to change.

Hint: Try opening several tabs to the same page. You'll notice the numbers all coincide and update at the same time.