Hi, we are considering a policy for REST API end point result format versioning and negotiation. The background and considerations are spelled out in a task and mw.org page: https://phabricator.wikimedia.org/T124365 https://www.mediawiki.org/wiki/Talk:API_versioning Based on the discussion so far, have come up with the following candidate solution: 1) Clearly advise clients to explicitly request the expected mime type with an Accept header. Support older mime types (with on-the-fly transformations) until usage has fallen below a very low percentage, with an explicit sunset announcement. 2) Always return the latest content type if no explicit Accept header was specified. We are interested in hearing your thoughts on this. Once we have reached rough consensus on the way forward, we intend to apply the newly minted policy to an evolution of the Parsoid HTML format, which will move the data-mw attribute to a separate metadata blob. Gabriel Wicke

The IRC discussion just finished, thanks to everybody who participated! You can read a full log on the task [1]. Here is a short summary: == Question 1: How to request a specific response format == Overall there was a slight preference for using the Accept header over query strings for format negotiation. It was noted that support for query strings can be added additionally at a later point. == Question 2: What to do if no format was specified == The main question in the discussion was whether strong encouragement will be enough to persuade clients to explicitly specify a format version. A common concern was that clients without explicit version in the request won't pay attention to announcements either, and will only find out when things break. There was consensus for starting with strong encouragement and quick default changes. If most clients continue to omit explicit versions in their requests, then we can reconsider *forcing* clients to supply a version. == Next steps == The Architecture Committee will officially decide this matter based on the discussion at next Wednesday's meeting. Gabriel [1]: https://phabricator.wikimedia.org/T124365#2036959 On Mon, Feb 15, 2016 at 7:41 PM, Gabriel Wicke <gwicke(a)wikimedia.org> wrote: -- Gabriel Wicke Principal Engineer, Wikimedia Foundation