AJAX: Implemention of ifModified attribute for pushing changes to server

[nemesis02]

Implements If-Match, and If-Unmodified-Since request headers under POST, POST and DELETE types since If-Modified-Since and If-None-Match are mainly retrieval operations.

[addyosmani]

Deferring to jaubourg for thoughts on this.

[jaubourg]

Everything is in "mainly". It should be pretty easy to implement this behaviour using a prefilter. Come to think of it, the ifmodified option could and should actually be handled that way.

I'm really not convinced here. I'd be tempted to tag it ajaxHooks... if there was such a tag.

[rdfedor@…]

the current tags that are in there apply for the retrieval of data only under the ifmodified attribute, the post versions don't make sense if you say them out loud from a version control perspective. You want to push a change if an etag matches that to which you last retrieved, not if etag doesn't match. Similar behaviours just different purposes, or direction to which the data is going. If an etag does not match via post, it means the data has changed since the last time that user retrieved the data and he should update his request to ensures latest changes are saved and data isnt overwritten.

[timmywil]

We'll keep this as implementable in a prefilter.