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RSP-QL Example Queries

Background data

The following data exists at the URI http://temp-data.org#:

@prefix prov: <http://www.w3.org/ns/prov#> .
@prefix dbp: <http://dbpedia.org/resource/> .
@prefix dbo: <http://dbpedia.org/ontology/> .
@prefix loc: <http://example.org/local/vocabulary/> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

dbp:Berlin a dbo:City .
dbp:London a dbo:City .

# more to come...

Streaming data

The following stream is available as http://sensor-stream.org/

@prefix prov: <http://www.w3.org/ns/prov#> .
@prefix dbp: <http://dbpedia.org/resource/> .
@prefix loc: <http://example.org/local/vocabulary/> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

_:b0  prov:generatedAtTime "2018-01-01T01:00:00Z"^^xsd:dateTimeStamp .
_:b0 {
    dbp:Berlin loc:hasPointTempC "12.5"^^xsd:decimal .
}

_:b1  prov:generatedAtTime "2018-01-01T01:01:00Z"^^xsd:dateTimeStamp .
_:b1 {
    dbp:Berlin loc:hasPointTempC "12.5"^^xsd:decimal .
}
	
_:b2  prov:generatedAtTime "2018-01-01T01:02:00Z"^^xsd:dateTimeStamp .
_:b2 {
    dbp:Berlin loc:hasPointTempC "12.0"^^xsd:decimal .
}
	
_:b3  prov:generatedAtTime "2018-01-01T01:03:00Z"^^xsd:dateTimeStamp .
_:b3 {
    dbp:London loc:hasPointTempC "11.5"^^xsd:decimal .
}
	
_:b4  prov:generatedAtTime "2018-01-01T01:04:00Z"^^xsd:dateTimeStamp .
_:b4 {
    dbp:Berlin loc:hasPointTempC "11.0"^^xsd:decimal .
}
	
_:b5  prov:generatedAtTime "2018-01-01T01:05:00Z"^^xsd:dateTimeStamp .
_:b5 {
    dbp:London loc:hasPointTempC "10.5"^^xsd:decimal .
}
	
_:b6  prov:generatedAtTime "2018-01-01T01:06:00Z"^^xsd:dateTimeStamp .
_:b6 {
    dbp:Berlin loc:hasPointTempC "10.0"^^xsd:decimal .
}
	
_:b7  prov:generatedAtTime "2018-01-01T01:08:00Z"^^xsd:dateTimeStamp .
_:b7 {
    dbp:Berlin loc:hasPointTempC "9.0"^^xsd:decimal .
}
	
_:b8  prov:generatedAtTime "2018-01-01T01:10:00Z"^^xsd:dateTimeStamp .
_:b8 {
    dbp:Berlin loc:hasPointTempC "8.5"^^xsd:decimal .
}

Queries

Query 1

Generate a stream including all events reporting temperatures below 10 C.

PREFIX prov: <http://www.w3.org/ns/prov#>
PREFIX dbp: <http://dbpedia.org/resource/>
PREFIX loc: <http://example.org/local/vocabulary/>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>

REGISTER ISTREAM <stream-below-10-degrees> AS
CONSTRUCT {
    _:b prov:generatedAtTime ?time .
    GRAPH _:b {
        ?city loc:hasPointTempC ?temp .
    }
}
FROM NAMED WINDOW <w> ON <http://sensor-stream.org/> [RANGE PT10S STEP PT1S]
WHERE {
   WINDOW <w> {
      ?city loc:hasPointTempC ?temp .
   }
   FILTER(?temp < 10)
   BIND(NOW() AS ?time)
}

Expected result

Timestamp Results
2018-01-01T01:00:06Z no result
2018-01-01T01:00:07Z no result
2018-01-01T01:00:08Z _:b1 prov:generatedAtTime "2018-01-01T01:08:00Z"^^xsd:dateTimeStamp . _:b1 { dbp:Berlin loc:hasPointTempC "9.0"^^xsd:decimal }
2018-01-01T01:00:09Z no result
2018-01-01T01:00:10Z _:b2 prov:generatedAtTime "2018-01-01T10:10:00Z"^^xsd:dateTimeStamp . _:b2 { dbp:Berlin loc:hasPointTempC "8.5"^^xsd:decimal }
2018-01-01T01:00:11Z no result

Discussion

Robin: Can we somehow access the generation time reported in the original events? Since all streamed graphs are placed in the same default graph this does not seem feasible. Instead it would have to be included within each individual event.

Robin: What will be the reports at 2018-01-01T01:00:09Z through 2018-01-01T01:00:11Z? Istream has been defined as ( informally) "everything that was not in present in the previous evaluation", which should mean that the observation at 2018-01-01T01:08:00Z will appear again in 2018-01-01T01:10:00Z. Is this the correct interpretation? Otherwise, do we need to revisit the meaning of Istream?

Query 2

Generate a stream reporting only the most recent temperature reading (highest timestamp) for each city.

PREFIX prov: <http://www.w3.org/ns/prov#>
PREFIX dbp: <http://dbpedia.org/resource/>
PREFIX loc: <http://example.org/local/vocabulary/>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>

REGISTER RSTREAM <most-recent-per-city> AS
CONSTRUCT {
    _:b prov:generatedAtTime ?time .
    GRAPH _:b {
        ?city loc:hasPointTempC ?temp .
    }
}
FROM NAMED WINDOW <w> ON <http://sensor-stream.org/> [RANGE PT10S STEP PT10S] # tumbling window
WHERE {
   WINDOW <w> {
      ?city loc:hasPointTempC ?temp .
   }
   # ????????????????
}

Expected result

Timestamp Results
2018-01-01T01:00:00Z _:b0 prov:generatedAtTime "2018-01-01T01:00:00Z"^^xsd:dateTimeStamp . _:b0 { dbp:Berlin loc:hasPointTempC "12.5"^^xsd:decimal }
2018-01-01T01:00:01Z _:b1 prov:generatedAtTime "2018-01-01T01:01:00Z"^^xsd:dateTimeStamp . _:b1 { dbp:Berlin loc:hasPointTempC "12.5"^^xsd:decimal }
2018-01-01T01:00:02Z _:b2 prov:generatedAtTime "2018-01-01T01:02:00Z"^^xsd:dateTimeStamp . _:b2 { dbp:Berlin loc:hasPointTempC "12.0"^^xsd:decimal }
2018-01-01T01:00:03Z _:b2 prov:generatedAtTime "2018-01-01T01:02:00Z"^^xsd:dateTimeStamp . _:b2 { dbp:Berlin loc:hasPointTempC "12.0"^^xsd:decimal } . _:b3 prov:generatedAtTime "2018-01-01T01:03:00Z"^^xsd:dateTimeStamp . _:b3 { dbp:London loc:hasPointTempC "11.5"^^xsd:decimal }
2018-01-01T01:00:04Z _:b3 prov:generatedAtTime "2018-01-01T01:03:00Z"^^xsd:dateTimeStamp . _:b3 { dbp:London loc:hasPointTempC "11.5"^^xsd:decimal } _:b4 . prov:generatedAtTime "2018-01-01T01:04:00Z"^^xsd:dateTimeStamp . _:b4 { dbp:Berlin loc:hasPointTempC "11.0"^^xsd:decimal }
2018-01-01T01:00:05Z _:b4 prov:generatedAtTime "2018-01-01T01:04:00Z"^^xsd:dateTimeStamp . _:b4 { dbp:Berlin loc:hasPointTempC "11.0"^^xsd:decimal } . _:b5 prov:generatedAtTime "2018-01-01T01:05:00Z"^^xsd:dateTimeStamp . _:b5 { dbp:London loc:hasPointTempC "10.5"^^xsd:decimal }
2018-01-01T01:00:06Z _:b5 prov:generatedAtTime "2018-01-01T01:05:00Z"^^xsd:dateTimeStamp . _:b5 { dbp:London loc:hasPointTempC "10.5"^^xsd:decimal } . _:b6 prov:generatedAtTime "2018-01-01T01:06:00Z"^^xsd:dateTimeStamp . _:b6 { dbp:Berlin loc:hasPointTempC "10.0"^^xsd:decimal }
2018-01-01T01:00:07Z _:b5 prov:generatedAtTime "2018-01-01T01:05:00Z"^^xsd:dateTimeStamp . _:b5 { dbp:London loc:hasPointTempC "10.5"^^xsd:decimal } . _:b7 prov:generatedAtTime "2018-01-01T01:08:00Z"^^xsd:dateTimeStamp . _:b7 { dbp:Berlin loc:hasPointTempC "9.0"^^xsd:decimal }
2018-01-01T01:00:08Z _:b5 prov:generatedAtTime "2018-01-01T01:05:00Z"^^xsd:dateTimeStamp . _:b5 { dbp:London loc:hasPointTempC "10.5"^^xsd:decimal } . _:b7 prov:generatedAtTime "2018-01-01T01:08:00Z"^^xsd:dateTimeStamp . _:b7 { dbp:Berlin loc:hasPointTempC "9.0"^^xsd:decimal }
2018-01-01T01:00:09Z _:b5 prov:generatedAtTime "2018-01-01T01:05:00Z"^^xsd:dateTimeStamp . _:b5 { dbp:London loc:hasPointTempC "10.5"^^xsd:decimal } . _:b7 prov:generatedAtTime "2018-01-01T01:08:00Z"^^xsd:dateTimeStamp . _:b7 { dbp:Berlin loc:hasPointTempC "9.0"^^xsd:decimal }
2018-01-01T01:00:10Z _:b5 prov:generatedAtTime "2018-01-01T01:05:00Z"^^xsd:dateTimeStamp . _:b5 { dbp:London loc:hasPointTempC "10.5"^^xsd:decimal } . _:b8 prov:generatedAtTime "2018-01-01T01:10:00Z"^^xsd:dateTimeStamp . _:b8 { dbp:Berlin loc:hasPointTempC "8.5"^^xsd:decimal }
2018-01-01T01:00:11Z _:b5 prov:generatedAtTime "2018-01-01T01:05:00Z"^^xsd:dateTimeStamp . _:b5 { dbp:London loc:hasPointTempC "10.5"^^xsd:decimal } . _:b8 prov:generatedAtTime "2018-01-01T01:10:00Z"^^xsd:dateTimeStamp . _:b8 { dbp:Berlin loc:hasPointTempC "8.5"^^xsd:decimal }

Discussion

Robin: Without accessing the timestamp associated with the incoming events I don't see how this can be done, without CEP operators that is.