On 6/19/15, 14:39, "Ian Cordasco" <ian.corda...@rackspace.com> wrote:
> > >On 6/19/15, 14:26, "Kevin L. Mitchell" <kevin.mitch...@rackspace.com> >wrote: > >>On Fri, 2015-06-19 at 10:07 +0100, Chris Dent wrote: >>> * Are there additional relevant pros and cons for the two proposals? >>> * Are there additional proposals which can address the shortcomings >>> in either? >> >>On the latter question, would using the If-Modified-Since header[1] make >>any sense as a possible solution? That at least would be a standard >>HTTP convention for this sort of thing, and tends to match up with the >>semantics of a changes-since query parameter. > >First, please use the updated RFC references >(https://tools.ietf.org/html/rfc7232#section-3.3) > >If-Modified-Since does not. That's meant for entire resources. In other >words, let's say you're listing images in Glance and you do > > GET /v2/images > >And your response has > > HTTP/1.1 200 OK > Last-Modified: some_last_modified_value > >In the headers, when you do > > GET /v2/images > If-Modified-Since: some_last_modified_value > >Then you should either get a: > > HTTP/1.1 204 No Content > >Or > > HTTP/1.1 200 OK > Last-Modified: new_last_modified_value > > (all of the images you saw before) > >In other words, If-Modified-Since is meant purely for the state of the >resource. It's main purpose is when used in conjunction with caching. > >That said, changes-since is more of a "delta". If you need an analogy, >think of it as an equivalent to > > $ git log 2015.1.0..stable/kilo > >It's just the deltas after a certain timestamp. Also, for what it's worth, I used to think If-Modified-Since was what you thought it was, but I found out how woefully wrong I was. It's not exactly intuitive, but you can toy with it via the GitHub API. Their /users and /repos resources will give you ETag and Last-Modified information. If you wait a little long enough for it to change and use either of those values to make a request, you'll get all of it again, from the beginning. >Cheers, >Ian __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
