
Originally Posted by
elanthis
... the same way any other application opens a "push" socket (which isn't a real thing).
In terms of streaming videos, it does it the same way any other video streaming app does it. HTML5 video doesn't use regular AJAX requests or anything for video, it mandates that the browser supports built-in native video streaming just like Flash or whatnot does.
If you're asking how general Web apps do push updates, there's a few different ways. The only cross-browser method is to poll the server for updates, or to use "never-ending" HTTP responses (which are problematic on several levels). There's also some new HTML5 features like server-sent DOM events and WebSockets, but those are not universally supported and are still very very rarely used by real applications.