UPDATE [2018–02–21]: initial code contained a major drawback that leads to threads hangs. My apologies! Please see the new section “SSE on AspNet Core (done right)”. Let’s consider we need to build an admin web console in an app for displaying log/diagnostics events in real-time. I used to use Server Sent Event (SSE) technology for such a task. And recently migrated that code from WebApi 2 onto As