Container Index

The container includes an index file, queries.ttl, which is a Turtle graph that describes each stored SPARQL query entry using terms from SPARQL 1.1, SHACL, and Service Description.

SPARQL query file serialization (.rq)

Each SPARQL query entry includes a serialization of the SPARQL algebra for the query, stored in a file named {hash}.rq.

• MUST be named to match the source query entry's {hash}.
• MUST declare media type application/sparql-query.

          PREFIX : <https://example.org/ontology/>
          SELECT ?s ?score WHERE { ?s :score ?score } ORDER BY DESC(?score) LIMIT 10
        

Results file serialization

Each SPARQL query entry includes a serialization of the results for the query, stored in a file named {hash}.* (where "*" is the descriptive extension of the file-type respresented).

• MUST be named to match the source query's {hash}.
• MUST use either SPARQL Results JSON (application/sparql-results+json) or SPARQL Results XML (application/sparql-results+xml) serialization formats.

Example - queries.ttl

          @prefix rdfs: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
          @prefix prov: <http://www.w3.org/ns/prov#> .
          @prefix qvmc: <https://vocab.example/qvmc#> .
          @prefix dc: <http://purl.org/dc/terms/> .
          @prefix sh: <http://www.w3.org/ns/shacl#> .
          @prefix tq: <http://www.w3.org/2001/sw/DataAccess/tests/test-query#> .
          @prefix tm: <http://www.w3.org/2001/sw/DataAccess/tests/test-manifest#> .
          @prefix sd: <http://www.w3.org/ns/sparql-service-description#> .
          @prefix se: <https://purl.expasy.org/sparql-examples/ontology#> .
          @base <https://data.example.org/example/> .

          <#index> a qvmc:Index ;
          dc:title "SPARQL Query Materialization Container Example" ;
          dc:modified "2025-09-25T09:00:00Z"^^xsd:dateTime .

          <#aBc1d2Ef3g> a tq:QueryForm, tq:QuerySelect, sh:SPARQLExecutable ;
            dc:title "Top 10 by score" ;
            dc:description "Returns 10 entities with the highest :score." ;
            tq:query <aBc1d2Ef3g.rq> ;
            tm:result <aBc1d2Ef3g.srj> ;
            sh:select "SELECT ?s ?score WHERE { ?s :score ?score } ORDER BY DESC(?score) LIMIT 10" ;
            sd:endpoint <#5926e69f-c619-4029-b516-21affc0598e0> ;
            dc:created "2025-09-24T16:12:03Z"^^xsd:dateTime ;
            qvmc:status "current" ;
            prov:wasGeneratedBy [
              a prov:Activity ;
              prov:used <aBc1d2Ef3g.rq>, <#5926e69f-c619-4029-b516-21affc0598e0> ;
              prov:modified "2025-09-24T16:12:03Z"^^xsd:dateTime
            ] .

          <#5926e69f-c619-4029-b516-21affc0598e0> rdfs:first <https://sparql.example.org/sparql/> ;
            rdfs:rest rdfs:nil .
        

Security & privacy considerations

• The discussed container and resource structure is designed to be configured with any additional access controls at a user's discretion.
• Consider cache-control headers for implementations where access controls are used and stored data should not be cached by intermediaries.
• Endpoints and dataset IRIs in the index may reveal infrastructure; redact if necessary.

HTTP interactions

Security and Privacy Note: If access controls are implemented, the following operations are permitted only if authorization is successful:

• Implementations MUST expose the container as an ldp:BasicContainer with GET and POST/PUT access rights on all resources for at least one authorized user.
• Implementations MAY support authenticated GET and POST/PUT methods to other authenticated users and/or the public.

Updating the index

Implementations MUST update queries.ttl atomically when new members are added, deleted, or modified. The following describes the requirements for each action:

• Add: When a new query entry is added, create a new tq:QueryForm node with a new unique subject IRI <#${name}>. Both results and query serialization files SHOULD be named <#${name}.rq> and <#${name}.*> respectively after the <#${name}> of the tq:QueryForm node. Set sd:endpoint to an RDF list of one or more source URIs that the query targets. Set dc:created to the creation timestamp.
...
• Modify: For an existing query entry, if the dataset changes or a new execution of the same SPARQL query over the same sources gives different results, update the qvmc:status of the relevant tq:QueryForm node to stale. IMPORTANT if the results of the query change, users SHOULD create a new query entry instead of modifying the existing one to preserve provenance. In this case, the pre-existing entry's qvmc:status MUST be set to stale and the triple qvmc:linkedQuery <#${updated-entry-name}> MUST be added. Whenever a field within an entry is updated, users MUST update prov:wasGeneratedBy with a new timestamp via dc:modified.
• Delete: When a query entry is deleted, remove the corresponding tq:QueryForm node and all references to its associated files (.rq, .srj, .srx) from queries.ttl. Optionally, remove the files themselves from the container.

          PATCH /views/queries.ttl HTTP/1.1
          Content-Type: application/sparql-update

          DELETE { <#aBc1d2Ef3g> dct:modified ?t ; qvmc:status ?s }
          INSERT { <#aBc1d2Ef3g> dct:modified "2025-09-25T10:01:22Z"^^xsd:dateTime ; qvmc:status "current" }
          WHERE { OPTIONAL { <#aBc1d2Ef3g> dct:modified ?t ; qvmc:status ?s } }