[Cubicweb] Multisource in CW

Sylvain Thénault sylvain.thenault at logilab.fr
Wed May 23 10:50:42 CEST 2012

On 23 mai 10:43, Olivier CAYROL wrote:
> Le 23/05/2012 10:24, Sylvain Thénault a écrit :
> >I'm not sure to get your point here.
> >
> >Here are my points :
> [...]
> As far as I know, the first idea behind the implementation of Vincent is
> to be able to connect or unconnect external CW bases without breaking
> the main base. I don't know if it's actually working with his first
> naive implementations but here is what we would want to do (Vincent,
> correct me if I'm wrong):
> In the main base, we select "Any X WHERE X contains_reference Y". Y is
> just a dbpedia URI. If we have set up an external base with dbpedia
> content, we would like to get some complementary data about Y, such as
> "Any L,D WHERE  Y label L, Y depiction D". So, what we would like to
> have is a query that always gives us X but can give us L and D if an
> external dbpedia CW base is available.
> I don't know if the standard source abstraction mechanism allows this
> kind of behaviour (the query continues in an external CW base only if
> this base is set up, else the query stops and returns the results it has
> found in the main base).

Eg. you expect to get the URI but None for attributes if the ext. database
isn't connected? IMO if the database isn't connected we shouldn't have
anything at all for this record, else it would imply to much defensive
programming on the ui side.

What I feel is that we've already have the foundation to make it works as
you wish without reinventing a lot of stuff already in. Working on a query
planner and way to deal with disconnected sources sounds like a good path
to follow (at least I've not seen any show-stopper in what I've read yet).
Sylvain Thénault, LOGILAB, Paris ( - Toulouse (
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