Documentation for JSON / binary query result format extensions for edge properties

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1

Hi there,

In the Stardog documentation it is mentioned that Stardog supports SELECT query results involving edge properties:

SPARQL SELECT query results with edge properties can be sent over in the XML, binary, and JSON format (content types application/sparql-results+xml , application/x-binary-rdf-results-table , and application/sparql-results+json , respectively).

Is there any documentation available or do you have any examples of how you extended these syntax formats to deal with edge property bindings?

2

Hi Jeen,

We don't have documentation about these details but let me briefly describe them here with some examples.

For XML and JSON, we introduced an additional statement value type with required s, p, o fields and an optional g field. Binding a variable x to a statement would look like this in JSON:

{
        "p": {
          "type": "uri",
          "value": "http://api.stardog.com/date"
        },
        "s": {
          "type": "statement",
          "s": {
            "type": "uri",
            "value": "http://api.stardog.com/Alice"
          },
          "p": {
            "type": "uri",
            "value": "http://api.stardog.com/knows"
          },
          "o": {
            "type": "uri",
            "value": "http://api.stardog.com/Bob"
          }
        },

and like this in XML:

<binding name='x'>
    <statement>
        <s>
            <uri>http://api.stardog.com/Alice</uri>
        </s>
        <p>
            <uri>http://api.stardog.com/knows</uri>
        </p>
        <o>
            <uri>http://api.stardog.com/Bob</uri>
        </o>
    </statement>
</binding>

For the binary results, there is an additional STATEMENT_RECORD_MARKER = 10 to indicate the RDF value is a statement. SPO components are serialized without any markers between them followed by either a DEFAULT_GRAPH_RECORD_MARKER = 1 or NAMED_GRAPH_RECORD_MARKER = 2(latter is followed by an RDF resource).

Best,
Evren

4

Thanks so much Evren, exactly what I needed!

5

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