Re: RDF Queries?

From: <franklin.reynolds@nokia.com>
> Is the query service intended to be similar to SQL?

No, there is no query language as such.   Each method in the query interface
is a canned query, parameterized by the method arguments.

>
> Are the functions get_child_values() and get_descendent_values()
> the primary methods for traversing a graph?
>

More or less.  Single-valued properties are traversed by get_values(),
many-valued properties are traversed by get_child_values().  The word
"child" is perhaps missused, since we are not traversing a tree.

The get_extent_values() method traverses whatever the inverse property of
rdf:type is.

The get_descendent_values() method is a short form for repeated
get_child_values() invokations.

The interface is a compromise between simplicity and efficiency.  In
particular, we kept the fixed cost of each call in mind (e.g network
latency).  It must be possible for an application to obtain a reasonable
amount of information in each operation.  Thus each method returns values
for many properties and, usually, many resources.

I hope that helps,
Arnold.

---
Arnold deVos
Langdale Consultants
adv@langdale.com.au

Received on Thursday, 7 October 1999 19:46:09 UTC