A comparison between WebSockets, server-sent events, and polling

Comparisons of mechanisms to implement a "real-time" behavior in web applications often touch on API differences, however neglect performance and request overhead in such implementations. This article provides metrics for HTTP long-polling, HTTP short-polling, server-sent events, and WebSockets in the form of bandwidth per request. The primary audience of this article is a seasoned web developer or library author, however web developers of all skill levels may benefit from the following material.