Comet (programming)

Comet is a web application model in which a long-held HTTPS request allows a web server to push data to a browser, without the browser explicitly requesting it.^[1][2] Comet is an umbrella term, encompassing multiple techniques for achieving this interaction. All these methods rely on features included by default in browsers, such as JavaScript, rather than on non-default plugins. The Comet approach differs from the original model of the web, in which a browser requests a complete web page at a time.^[3]

The use of Comet techniques in web development predates the use of the word Comet as a neologism for the collective techniques. Comet is known by several other names, including Ajax Push,^[4][5] Reverse Ajax,^[6] Two-way-web,^[7] HTTP Streaming,^[7] and HTTP server push^[8] among others.^[9] The term Comet is not an acronym, but was coined by Alex Russell in his 2006 blog post.^{[10][citation needed]}

In recent years^[when?], the standardisation and widespread support of WebSocket and Server-sent events has rendered the Comet model obsolete.