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Ian Dunlop

Aug 18, 2017, 10:09:00 AM8/18/17
to linked-data-api-discuss

Is there a way to get ELDA to produce a CONSTRUCT query? eg the W3C example:

PREFIX foaf:    <>
PREFIX vcard:   <>
CONSTRUCT   { <> vcard:FN ?name }
WHERE       { ?x foaf:name ?name }

I noticed that ELDA can use properties where you could get something like:
CONSTRUCT   { ?item vcard:FN ?name }

but I want to be able to fully define the triple patterns.

The back story is that I have inherited an old puelia app and want to see whether I could move the config to ELDA. Most of the queries use CONSTRUCT where the api:template defines the CONSTRUCT and the api:where the WHERE clause. What I'm not clear on is whether this is functionality that some 3rd party added into puelia or if it was the standard code that could do it.

Info and/or examples would be much appreciated.



Rob Atkinson

Aug 20, 2017, 9:52:49 PM8/20/17
to linked-data-api-discuss

Tried this some time ago see:

the email discussion basically informed me ELDA's purity depended somehow on not returning anything not in the triple store.  I still dont really get that.

Possibly many of your constructs can be rewritten manually as property chains - but note this wont handle any inbound references to the objects - easy to include in CONSTRUCT, or any manipulation to derive content.

Anyway for me the solution is largely through entailment of the graphs i need in the triple-store, using RDF4J and SPIN for example.

The other big ticket item is to be able to deconstruct variables in the request - for example extracting a namespace from a URI and running a query using that as a filter.

At this stage I'm waiting for a lightweight replacement that handles views, flexible constructors, and probably ignores optional properties aspect of queries.

Puelia seems to be unmaintained, and I dont really want to add PHP to my stack - which is mainly Django and Tomcat apps. (

Anybody got other implementations, or other APIs they think meet the goals of content-negotiation over multiple views?

For interest, the general issue of "negotiation by profile" - which reasonably closely equates to choice of _view in LDA - is live topic of the W3C Data Exchange WG (

Rob Atkinson

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