[occi-wg] Is AtomPub already the HTTP of cloud computing?

[Sam Johnston]

Second post in the three-post series:
Is AtomPub already the HTTP of cloud
computing?<http://samj.net/2009/05/is-atompub-already-http-of-cloud.html>A
couple of weeks ago I asked Is OCCI the HTTP of cloud
computing?<http://samj.net/2009/05/is-occi-http-of-cloud-computing.html>I
explained the limitations of HTTP in this context, which basically
stem
from the fact that the payloads it transfers are opaque. That's fine when
they're [X]HTML because you can express links between resources within the
resources themselves, but what about when they're some other format - like
OVF describing a virtual machine as may well be the case for OCCI? If I want
to link between a virtual machine and its network(s) and/or storage
device(s) then I'm out of luck... I need to either find an existing
meta-model or roll my own from scratch.

That's where Atom (or more specifically, AtomPub) comes in... in the
simplest sense it adds a light, RESTful XML layer to HTTP which you can
extend as necessary. It provides for collections (a 'feed' of multiple
resources or 'entries' in a single HTTP message) as well as a simple
meta-model for linking between resources, categorising them, etc. It also
gives some metadata relating to unique identifiers, authors/contributors,
caching information, etc., much of which can be derived from HTTP (e.g. URL
<-> Atom ID, Last-Modified <-> updated).

Although it was designed with syndication in mind, it is a very good fit for
creating APIs, as evidenced by its extensive use in:

   - Google's GData <http://code.google.com/apis/gdata/>
   - Microsoft's Live
Services<http://www.25hoursaday.com/weblog/CommentView.aspx?guid=8c8b2311-96c9-41b9-badd-51e68d4ce995>
   - IBM's Lotus
Connections<http://www.ibm.com/developerworks/lotus/library/connections-deploy-pt6/>
   - SalesForce.com's Google Apps
Integration<http://www.dehora.net/journal/2008/06/24/salesforcecom-and-google-integration-atompub/>

I'd explain in more detail but Mohanaraj Gopala Krishnan has done a great
job already in his AtomPub, Beyond
Blogs<http://www.slideshare.net/mohangk/atompub-beyond-blogs?type=presentation>presentation.

The only question that remains is whether or not this is the best we can
do... stay tuned for the answer. The biggest players in cloud computing seem
to think so (except Amazon, whose APIs predate Google's and Microsoft's) but
maybe there's an even simpler approach that's been sitting right under our
noses the whole time.
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