[openstack-dev] [api] Counting resources

Christopher Yeoh cbkyeoh at gmail.com
Thu Nov 20 14:24:55 UTC 2014

On Thu, 20 Nov 2014 14:47:16 +0100
Salvatore Orlando <sorlando at nicira.com> wrote:

> Aloha guardians of the API!
> I haven recently* reviewed a spec for neutron [1] proposing a
> distinct URI for returning resource count on list operations.
> This proposal is for selected neutron resources, but I believe the
> topic is general enough to require a guideline for the API working
> group. Your advice is therefore extremely valuable.
> In a nutshell the proposal is to retrieve resource count in the
> following way:
> GET /<prefix>/<resource_name>/count
> In my limited experience with RESTful APIs, I've never encountered
> one that does counting in this way. This obviously does not mean it's
> a bad idea. I think it's not great from a usability perspective to
> require two distinct URIs to fetch the first page and then the total
> number of elements. I reckon the first response page for a list
> operation might include also the total count. For example:
> {'resources': [{meh}, {meh}, {meh_again}],
>  'resource_count': 55
>  <link_to_next_page>}
> I am however completely open to consider other alternatives.
> What is your opinion on this matter?

FWIW there is a nova spec proposed for counting resources as
well (I think it might have been previously approved for Juno). 


I haven't compared the two, but I can't think of a reason we'd
need to be any different between projects here.



> Regards,
> Salvatore
> * it's been 10 days now
> [1] https://review.openstack.org/#/c/102199/

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