SPARQL End Point Self Description
I was at the ISWC 2006 conference a week back. One of the items discussed there, at least informally, was the topic of SPARQL end point discovery. I have below put together a summary of points that were discussed and of my own views on their possible resolution.
This is intended as a start for conversation and as a summary of ideas.
Self-description of end points may serve at least the following purposes:
We will look at each one in turn.
The end point should give a ballpark cardinality for the following combinations of G, S, P, O.
Based on our experience, these are the most interesting questions but for completeness, the entry point might offer an API allowing specifying a constant or wildcard for each of the four parts of a quad. If the information is not readily available, "unknown" could be returned, together with the count of triples in the whole end point or the graph, if the graph is specified. Even if the end point does not support real time sampling of data for cardinality estimates, it would at least have an idea of the count of triples per graph, which is still far better than nothing.
Given the full SPARQL request, the end point could return the following data, without executing the query itself.
All these elements would be optional.
This somewhat overlaps with the optimization questions but it may still be the case that it is more efficient to support a special interface for the optimization related questions.
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Author: Orri Erling
Published: 11/21/2006 14:30 GMT
04/16/2008 16:53 GMT
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