[occi-wg] Preliminary JSON rendering draft, discussion material

[Edmonds, AndrewX]

I completely agree with Ralf on the need for pagination. It's also worth looking at OpenStack's approach to pagination [1] as we have the semantics and syntax in the OCCI model to support this.

Andy

[1] http://docs.openstack.org/api/openstack-compute/1.1/content/Paginated_Collections-d1e664.html

-----Original Message-----
From: occi-wg-bounces at ogf.org [mailto:occi-wg-bounces at ogf.org] On Behalf Of Ralf Nyren
Sent: Thursday, January 19, 2012 11:16 AM
To: florian.feldhaus at tu-dortmund.de
Cc: occi-wg at ogf.org
Subject: Re: [occi-wg] Preliminary JSON rendering draft, discussion material


Nice summary Florian! Just one comment on the pagination issue, see below.

On Thu, 19 Jan 2012 10:53:04 +0000, <florian.feldhaus at tu-dortmund.de>
wrote:
>>The pagination of GET requests may also prove to be problematic, as 
>>resources may be deleted between successive GET requests. As mentioned 
>>above, I would prefer to have the OCCI server return ALL 
>>OCCI-Locations for a GET request and then let the client do additional 
>>GET requests for each resource.
> 
> We couldn't touch this subject properly in the call. From my point of 
> view, paginating requests is not a good idea, as we break the
non-stateful
> REST concept. We might consider the HTTP header field range to achieve 
> this behaviour. In general, I would prefer not to have pagination due 
> to the problem that it may be possible to add or remove entities from 
> the list between two consecutive requests with pagination.

I still believe we need pagination, client needs a way to avoid getting drowned in large collection responses.

Pagination is not a problem if the server does not guarantee that "page 2"
is based on the exact same collection as "page 1".

We simply say that in requesting collection items 10-20 you get those item based on the collection at the time of the request.

Example:
 - Client request items 1-10
 - A new item is added as "number 2" in the collection (based on the sorting rules chosen by the server implementation)
 - Client requests items 11-20. The client will see item "10" again but as number 11 in the list this time.

This should be easy enough to implement on the server side and this kind of pagination is better than none at all.

What do you think?

/Ralf
_______________________________________________
occi-wg mailing list
occi-wg at ogf.org
https://www.ogf.org/mailman/listinfo/occi-wg
-------------------------------------------------------------
Intel Ireland Limited (Branch)
Collinstown Industrial Park, Leixlip, County Kildare, Ireland
Registered Number: E902934

This e-mail and any attachments may contain confidential material for
the sole use of the intended recipient(s). Any review or distribution
by others is strictly prohibited. If you are not the intended
recipient, please contact the sender and delete all copies.