"Atom Publishing Protocol" and "Atom API": not synonyms

Back in 2003 there was a lot of buzz surrounding the (then new) Atom syndication format and its sister, the Atom API. Mark Pilgrim published an article about the API on XML.com, it was implemented in some high-profile applications (including Blogger and TypePad) and it generally wormed its way into people's brains.

Shortly afterward its name was changed to the Atom Publishing Protocol, erasing all that lovely brand recognition. Since then, the specifics of the Protocol have changed significantly. Most notably, the API is based on a draft version of the Atom format (now deprecated), while the Protocol is based on Atom 1.0. The two formats are just different enough to cause problems (barring extremely lenient software).

The similarity of the two names and the plethora of existing material about the API (Google turns up twice as many results for "atom api" as for "atom publishing protocol") are already confusing people. The Protocol will be an RFC any day now*, and it won't be good for anyone if implementors are looking at the wrong specs and users at the wrong clients.

I've seen this mistake made several times recently (1, 2); let's try to end the confusion.

* I've been saying that for months.