Re: SPARQL Federation Extensions draft


This is great - I think we ought to include something in SPARQL 1.1 even 
if it's just the most basic SERVICE form because of time.  It it the 
semantic *web* ....


On 27/03/2010 3:36 AM, Eric Prud'hommeaux wrote:
> take a look, help out, ...
> --
> -ericP

Specific comments:

"4.1 Definition of SERVICE"

The evaluation of service uses the SPARQL algebra union operator.

Elements of a group are usually join'ed together, not union'ed.

Algebra example:

  Service(?s :p2 ?v2)
  Service(<srvc> BGP(?s :p2 ?v2))

"with a query Q and no default or named graphs."

I think that means no FROM or FROM NAMED - correct?


This area is less clear to me - it's very useful to have something here 
but I'm not quite sure this is the right mechanism.

It's another form of assignment.

Is it the same as (the excessively verbose):

SELECT ("Alice" AS ?given)
        ("Anderson" AS ?family)
        (?mbox AS <>)
SELECT ("Bob" AS ?given)
        ("Robertson" AS ?family)
        (?mbox AS <>)
} UION { ... }

Probably better not to allow bNodes to be passed over the network.

Suggest s/UNBOUND/_/ or something a liitle less heavy. "-"
The definition of BINDING has UNDEF

* BINDING and Update:
This seems to overlap with INSERT DATA etc
It is unrelated to federated query.

The substutute operator might help in the definition:

Result are then a union of substitute for each binding row.  This is 
similar to the bind-join proposed by the IBM Garlic project.  It allows 
for the bINDINGs to be streamed in parallel with results coming back.

(this way the results of sending one BINDING at a time and sending all 
BINDINGS at once are the same).

** MIME Type

Doesn't the query often go in ?query= which isn't MIME typed.


Received on Monday, 29 March 2010 14:54:54 UTC