[oslc-core] oslc:totalSize Clarification

[Steve K Speicher]

> From: Dave <snoopdave at gmail.com>
> To: oslc-core <oslc-core at open-services.net>
> Date: 12/01/2010 12:40 PM
> Subject: [oslc-core] oslc:totalSize Clarification
> Sent by: oslc-core-bounces at open-services.net
> 
> I will write up the various paging-related issues we've been
> discussing, but I'd like to get this one on the table first.
> 
> Currently, we define a property of oslc:ResponseInfo named
> oslc:totalSize, which has occurrence of zero-or-one. We define this
> as: "Total number of results across all pages, its value should be
> non-negative" and thus are not clear about what we are counting.
> 
> The consensus in the work-groups is that we meant to say something
> like "total number of top-level resources returned across all pages"
> or "total number of member property values returned across all pages"
> and refer to the query spec for the definition of member property.
> But, in today's meeting we forgot about the fact that oslc:totalSize
> can be returned for not just query resource but also in "plain old"
> resources and in such a plain old resource, seems to me, the only
> thing oslc:totalSize could mean is total count of triples.
> 

I think the usage is similar if we think about the representation response 
that is being paged. The subject of the triples are the same, then it is 
really the same.

> Perhaps, what we need to do is to cover both of these cases, something
> like this:
> 
> oslc:totalSize - Total number of results across all pages, its value
> should be non-negative. In the context of a query resource, this value
> is the total number of member property values that match the query. In
> the context of other resources, the value is the total number of
> property values (i.e. RDF triples) of the resource.
> 
> Ideas?

I went looking for what SPARQL SELECT count() says, since I would assume 
it is what would be used to implement this.  Though this is a common 
extension to SPARQL and not in the specification, so you have to look at 
places like Jena ARQ [1].  Though this definition matches what we mean, it 
is still a bit unclear.

Having said that, I can't come up with anything better than what you have 
at the moment.  My only concern is "member property values that match the 
query", which to most people would be "rows".

[1] http://jena.sourceforge.net/ARQ/group-by.html

- Steve