Re: SPARQL 1.1 Federation Extensions

Dear William,

Currently, the Working Group has no plans to extend the federation 
extension to cover SPARQL update. There are several challenges with 
federated update that lead the group to conclude that the area is not 
yet mature enough for standardization.

The main problem of using the federation extension with update (and 
other extensions) is that you always rely in the remote server 
capabilities like security issues. Such security issues may involve 
security certificates or HTTP access and authorization. If HTTP access 
is used, credentials have to be sent and the SERVICE operator currently 
does not support that.

Another issue is the purpose of updating multiple updated endpoints. 
Then the operation may as well be executed as a set of separate 
operations. SPARQL has no concept of transactions, meaning that there 
can't be any guarantee of integrity across endpoints no matter what we 
do. It could be argued that the WHERE clause could be resolved into a 
single image that is used for consistent updates across stores, which 
may make integrity more likely, but it still can't be guaranteed.

We would be grateful if you would acknowledge that your comment has been 
answered by sending a reply to this mailing list.

Carlos, on behalf of the SPARQL-WG



On 14/03/2011 12:11, william greenly wrote:
> Are there any plans to extend federation extensions to cover SPARQL 
> Update.
>
> For nearly every example in the SPARQL Update WD, I can see a way to 
> incorporate federation extensions e.g:
>
> PREFIX dc: <http://purl.org/dc/elements/1.1/>
> INSERT DATA {
>  SERVICE <http://example1/sparql> {
>   GRAPH <http://example1/bookStore> {
> <http://example/book3>  dc:title  "Fundamentals of Compiler Design"
>   }
>   GRAPH <http://example1/bookstore2> {
> <http://example/book3>  dc:title  "Fundamentals of Compiler Design"
>   }
>   GRAPH <http://example1/bookstore3> {
> <http://example/book3>  dc:title  "Fundamentals of Compiler Design"
>   }
>  }
>  SERVICE <http://example2/sparql> {
>   GRAPH <http://example2/shop> {
> <http://example/book3>  dc:title  "Fundamentals of Compiler Design"
>   }
>   GRAPH <http://example2/shop2> {
> <http://example/book3>  dc:title  "Fundamentals of Compiler Design"
>   }
>  }
> }
>
> I am sure the benefits would be huge.
>
> Many Thanks,
>
> William Greenly
> Volkswagen UK Technical Lead