Server-Sent Events can be used by web applications or web sites to setup a
uni-directional (one-way) communication channel over a single TCP connection.
You can use it for push notifications from a server to a browser client.
Server-Sent Events sometimes provide an alternative to
usages of Ajax, HTTP Long Polling or Comet.
In the browser you can use Server-Sent Events via the EventSource API.
This API belongs to HTML5 and is standardized by the W3C:
http://www.w3.org/TR/eventsource/
ZAP is able to: