[ubuntu-cloud] Deprecation of Query2 format

[Ben Howard]

With 12.04 we introduced the Query2 [1], which is a machine readable
method of consuming information related to the Cloud Images. Users of
Query2 highlighted that the format producesunnecessarilyverbose
files,and thuswasnot easily consumed. Subsequently, we came to the
conclusion that a simplified format is needed in order to better serve
the needs of our users. In light of these concerns, we will be
deprecating the existing Query2  structure on 21 November 2012, pending
[2]. 

The simplified format can be found at [3]. The design principle behind 
the new Query2 format is to eventually provide a web service, and as
such, requests for the new format are accessed in an API-like way. Right
now the naming structure is fairly rigid and hierarchical (see [4] for
an example). The new Query2 format seeks to solve the deficiencies of
the old format by removing the static verbosity, and instead is loosely
structured with only a few required elements. We also standardized the
differences between the "build" and "ec2" data types, so that that
parsers for the new code can easily distinguish between response
types. The latest image or build is now identified by the response, and
we introduced a "request" section to validate the results and aide in
debugging. Finally, the new structure will allow for the addition of
future clouds, discovery of new versions of Ubuntu, and
self-documentation of API requests. 

The new format describes two principle ideas. The first is a  "cloud"
which describes the published images; right now only EC2 is supported.
The second is a "build" which describesthefiles which are downloadable.
The default behavior of the new format is to give as  little information
as possiblein orderto reduce parsing complexity. The trade off is that
you will need to request the right file to get the  information you
need. For example, [4] is a synonym of [5], as the format makes default
assumptions*.

Should you have any questions, comments,or concerns please feel free to
reach out to me directly. 

Thanks,
Ben Howard

[1]
https://wiki.ubuntu.com/PrecisePangolin/ReleaseNotes/UbuntuServer?action=recall&rev=47
[2]
https://blueprints.launchpad.net/ubuntu/+spec/servercloud-r-query2-deprecation
[3] https://cloud-images.ubuntu.com/query2
[4]
http://cloud-images.ubuntu.com/query2/data=cloud&distro=precise&arch=amd64&stream=server&instance_type=ebs&region=us-east-1
[5] https://cloud-images.ubuntu.com/query2/data=cloud&distro=precise


* Assumptions: Any request missing a request element will be filled in
using a default. The defaults are "arch" of "amd64" , "stream" of
"server", "instance_type" of  "ebs", EC2 region of "us-east-1" and
"release_tag" of "release".

-- 


Ben Howard
ben.howard at canonical.com
Canonical
GPG ID 0x5406A866



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