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second version of the example of RSP-QL query
I removed all the CEP features present in the previous version and I integrated (most of) the comments to previous version.
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| This query continuously look for bars where people are falling in love like Paolo and Francesca in Dante's Divine Comedy because of a book by Gallehault. | ||
| This query continuously look for bars where people are falling in love like [http://en.wikipedia.org/wiki/Francesca_da_Rimini#In_Inferno Paolo and Francesca in Dante's Divine Comedy] because of a book by [http://en.wikipedia.org/wiki/Galehaut Gallehault]. | ||
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| The query checks : | ||
| * over the default graph containing the points of interest (POIs) of http://somesocialnetwork.org/ that the POI is a bar. | ||
| * over the entire stream from http://someinvasivesensornetwork.org, that pairs of people entered in the poi in different moments within 4 hours. | ||
| * over the same stream, with a long lasting time window of 1 hour, that pairs of those people have been staying close by for at least 30 minutes. Note: that this may require some resoning being the property isCloseBy symmetric. | ||
| * over the same stream but with a short time window of 10 minutes, that the same pairs exit together. | ||
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| over the default graph containing the points of interest (POIs) of http://somesocialnetwork.org/ that the POI is a bar. | ||
| over the entire stream from http://someinvasivesensornetwork.org, that pairs of people entered in the poi in different moments within 4 hours. | ||
| over the same stream, with a long lasting time window of 1 hour, that pairs of those people have been staying close by for at least 30 minutes. Note: that this may require some resoning being the property isCloseBy symmetric. | ||
| over the same stream but with a short time window of 10 minutes, that the same pairs exit together. | ||
| As output, for each bar, it streams out an RDF graph with the list of pairs and the total number of pairs that felt in love. | ||
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| As output, for each bar, it streams out an RDF graph with the list of pairs and the total number of pairs that felt in love. | ||
| Note that this example query covers features of C-SPARQL, CQELS, and SPARQL-Stream as well as new features missing in all RSP languages: | ||
| * From C-SPARQL it takes the REGISTER clause, the FROM STREAM clause as dataset clause, the AT clause to access the timestamp (in C-SPARQL, AT is implemented with the timestamp() function) and the aggregates (which are computed in parallel without shrinking the result set, but extending it). | ||
| * From CQELS it takes the idea of the STREAM keyword in the WHERE clause, herein defined as WINDOW. | ||
| * From SPARQL-Stream it takes the ISTREAM clasue, that ask the RSP engine to use the R2S operator, and the notion of windows in the past. | ||
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| Note that this example query covers features of C-SPARQL, CQELS, SPARQL-Stream, EP-SPARQL as well as new features missing in all RSP languages: | ||
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| From C-SPARQL it takes the REGISTER clause, the FROM STREAM clause as dataset clause, the AT clause to access the timestamp (in C-SPARQL, AT is implemented with the timestamp() function) and the aggregates (which are computed in parallel without shrinking the result set, but extending it). | ||
| # so what is the AT time function doing? where is that timestamp coming from? | ||
| From CQELS it takes the idea of the STREAM keyword in the WHERE clause. | ||
| From SPARQL-Stream it takes the ISTREAM clasue that ask the RSP engine to use the R2S operator. | ||
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| From EP-SPARQL, it takes the SEQ and the WITH DURATION clauses (in EP-SPARQL, WITHIN DURATION is implemented with the getDuration() function). | ||
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| -->if we introduces new keyword SEQ for expressing order constraint, why don't we introduce keywords for 13 Allen's interval operator? for instance, BEFORE/MEETS/OVERLAPS/STARTS/DURING/FINISHES/EQUAL + inverse version of them (practically, it's the same effort for parsing) | ||
| Differently from a previous version of this query, it no longer covers features of EP-SPARQL such as SEQ or the getDuration() function. This reflects the decision to layer the complex event processing language on a continuous querying one. | ||
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| The new features are: | ||
| * the usage of an IRI to identify the query (and its stream of results) | ||
| * the optional UNDER ENTAILMENT REGIME clause | ||
| * the FROM NAMED WINDOW ON STREAM <<stream iri>> <<window>> AS << window name>> clause in the dataset declaration | ||
| * the WINDOW keyword in the WHERE clause | ||
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| the usage of an IRI to identify the query (and its stream of results) | ||
| the optional UNDER ENTAILMENT REGIME clause | ||
| the FROM NAMED STREAM <<stream iri>> <<window>> AS << window name>> clause in the dataset declaration | ||
| the WINDOW keyword in the WHERE clause | ||
| --> is there any shorter way to express this? for instance, just STREAM keyword inside WHERE? | ||
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| # this looks a bit different than sparql in terms of order of query blocks, would it harm to make it something like: | ||
| # PREFIX ... | ||
| # CONSTRUCT ISTREAM { ...etc | ||
| # FROM .... | ||
| # WHERE { ... | ||
| # AS :GallehaultWasTheBar | ||
| # UNDER ENTAILMENT xxx... | ||
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| PREFIX e: <http://somevocabulary.org/> | ||
| PREFIX s: <http://someinvasivesensornetwork.org/streams#> | ||
| PREFIX g: <http://somesocialnetwork.org/graphs#> | ||
| PREFIX : <http://acrasycompany.org/rsp#> | ||
| REGISTER STREAM :GallehaultWasTheBar | ||
| UNDER ENTAILMENT REGIME <http://www.w3.org/ns/entailment/RIF> | ||
| AS | ||
| FROM NAMED STREAM s:1 | ||
| FROM NAMED STREAM s:1 [RANGE PT1H STEP PT5M] AS :longWindow #it is strange to reference to :longWindow as NAMED STREAM here and WINDOW later... and can create confusion on users. Wouldn't be better to use the same keyword in both cases? | ||
| FROM NAMED STREAM s:1 [RANGE PT10M STEP PT5M] AS :shortWindow | ||
| FROM NAMED GRAPH g:SocialGraph | ||
| FROM GRAPH g:POIs | ||
| CONSTRUCT ISTREAM { | ||
| ?poi rdf:type :Gallehault ; | ||
| :count ?howmanycouples ; | ||
| :for (?somebody ?someoneelse) # I cannot understand this one clearly | ||
| } | ||
| WHERE { | ||
| ?poi rdf:type e:bar . | ||
| STREAM s:1 { | ||
| { ?somebody e:enters ?poi } | ||
| SEQ | ||
| { ?someoneelse ex:enters ?poi } WITHIN PT4H | ||
| } | ||
| # is this equivalent to : ? | ||
| # STREAM s:1 [RANGE PT1H STEP PT5M] { | ||
| WINDOW :longWindow { | ||
| { ?somebody e:isCloseTo ?someoneelse | ||
| MINUS { ?somebody e:isCloseTo ?yetanotherone . FILTER (?yetanotherone != ?someoneelse) } | ||
| } WITH DURATION ?longtime | ||
| FILTER (?longtime>"PT30M"^^xsd:duration) | ||
| <tt> | ||
| PREFIX e: <http://somevocabulary.org/> | ||
| PREFIX s: <http://someinvasivesensornetwork.org/streams#> | ||
| PREFIX g: <http://somesocialnetwork.org/graphs#> | ||
| PREFIX : <http://acrasycompany.org/rsp> | ||
| REGISTER STREAM :GallehaultWasTheBar | ||
| UNDER ENTAILMENT REGIME <http://www.w3.org/ns/entailment/RIF> | ||
| AS | ||
| FROM NAMED WINDOW ON STREAM s:1 [RANGE PT4H STEP PT1H] AS :veryLongWindow | ||
| FROM NAMED WINDOW ON STREAM s:1 [FROM NOW-PT35M TO NOW-PT5M STEP PT5M] AS :longWindow | ||
| FROM NAMED WINDOW ON STREAM s:1 [RANGE PT10M STEP PT5M] AS :shortWindow | ||
| FROM NAMED GRAPH g:SocialGraph | ||
| FROM GRAPH g:POIs | ||
| CONSTRUCT ISTREAM { | ||
| ?poi rdf:type :Gallehault ; | ||
| :count ?howmanycouples ; | ||
| :for (?somebody ?someoneelse) | ||
| } | ||
| WHERE { | ||
| ?poi rdf:type e:bar . | ||
| WINDOW :veryLongWindow { | ||
| ?somebody e:enters ?poi | ||
| ?someoneelse e:enters ?poi | ||
| } | ||
| WINDOW :longWindow { | ||
| ?somebody e:isCloseTo ?someoneelse | ||
| MINUS { ?somebody e:isCloseTo ?yetanotherone . FILTER (?yetanotherone != ?someoneelse) } | ||
| } | ||
| WINDOW :shortWindow { | ||
| { ?somebody e:exits ?bar} BEGIN AT ?t1 | ||
| { ?someoneelse e:exits ?bar } BEGIN AT ?t2 | ||
| FILTER (abs(?t2-?t1)<"PT1M"^^xsd:duration ) | ||
| } | ||
| GRAPH g:1 { | ||
| FILTER NOT EXIST { ?somebody e:knows ?someoneelse } | ||
| } | ||
| FILTER (?somebody != ?someoneelse) | ||
| } | ||
| # not sure if we need both WITHIN and WITH DURATION+FILTER | ||
| WINDOW :shortWindow { | ||
| { ?somebody e:exits ?bar} AT ?t1 | ||
| { ?someoneelse e:exits ?bar } AT ?t2 | ||
| FILTER (abs(?t2-?t1)<"PT1M"^^xsd:duration ) | ||
| AGGREGATE { | ||
| GROUP BY ?bar | ||
| COUNT(?somebody) AS ?howmanycouples | ||
| } | ||
| GRAPH g:1 { | ||
| FILTER NOT EXIST { ?somebody e:knows ?someoneelse } | ||
| } | ||
| FILTER (?somebody != ?someoneelse) | ||
| } | ||
| AGGREGATE { | ||
| GROUP BY ?bar | ||
| COUNT(?somebody) AS ?howmanycouples | ||
| } | ||
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| #are we creating a different type of aggregate syntax? i.e. not the one from SPARQL1.1? ok, for the construct you need something else, but could it be done with a subquery right? | ||
| </tt> |