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Java - SPARQL query rewriting through parsing
Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 23, 2019 at 23:30 UTC (7:30pm US/Eastern)
Data science time! April 2019 and salary with experience
The Ask Question Wizard is Live!Is Java “pass-by-reference” or “pass-by-value”?How do I read / convert an InputStream into a String in Java?When to use LinkedList over ArrayList in Java?How do I generate random integers within a specific range in Java?How do I parse a string to a float or int in Python?Iterate through a HashMapHow to parse JSON in JavaHow do you parse and process HTML/XML in PHP?Parse JSON in JavaScript?Creating a memory leak with Java
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I am trying to use Jena or some other Java library to achieve some coding challenge (in this case a rewriting through post-order traversal). I am not asking a methodology to translate SPARQL to SQL query. I already have that.
I am currently trying to translate a given SPARQL query into an some other SQL query.
So far, I've used Jena parser, that given a SPARQL query, returns an ARQ tree representation, that can be traversed in post-order. This is exactly what I want to do.
The only problem is that the Walker, just walks through the tree. What I would like to do, is something like this (suppose I am going through a MINUS) :
String visit(OpMinus minus)
String l_res = minus.getLeft().visit();
String r_res = minus.getRight().visit();
/*
... do some stuff with the result ...
*/
String res = l_res + "MINUS (" + r_res + ")";
return res;
Jena's visitor however returns void, making this impossible. Is there another way of doing it, instead of copying the Walker and the Visitor code, in order to make it work the way I want ? Thank you.
I am not looking for a SPARQL-to-SQL direct translator, because I need to work with the tree elements.
java parsing jena
edited Mar 22 at 21:54
TallTed
6,88521528
asked Mar 22 at 14:59
Valerio ColittaValerio Colitta
265
|
show 2 more comments
I am trying to use Jena or some other Java library to achieve some coding challenge (in this case a rewriting through post-order traversal). I am not asking a methodology to translate SPARQL to SQL query. I already have that.
I am currently trying to translate a given SPARQL query into an some other SQL query.
So far, I've used Jena parser, that given a SPARQL query, returns an ARQ tree representation, that can be traversed in post-order. This is exactly what I want to do.
The only problem is that the Walker, just walks through the tree. What I would like to do, is something like this (suppose I am going through a MINUS) :
String visit(OpMinus minus)
String l_res = minus.getLeft().visit();
String r_res = minus.getRight().visit();
/*
... do some stuff with the result ...
*/
String res = l_res + "MINUS (" + r_res + ")";
return res;
Jena's visitor however returns void, making this impossible. Is there another way of doing it, instead of copying the Walker and the Visitor code, in order to make it work the way I want ? Thank you.
I am not looking for a SPARQL-to-SQL direct translator, because I need to work with the tree elements.
java parsing jena
edited Mar 22 at 21:54
TallTed
6,88521528
asked Mar 22 at 14:59
Valerio ColittaValerio Colitta
265
A walker does not return anything, butTransformerand theTransformclasses do.
– AKSW
Mar 22 at 17:35
Your question suggests a generalized translation, but that is not possible, because SPARQL and SQL have significant differences. Virtuoso performs such translations in different ways for different jobs. Translating "a given" (do you mean "any given" or "a specific"?) SPARQL query to "an equivalent" SQL query depends on the SQL schema(s), SQL dialects, SQL engines, and RDF ontology/ies in use, among other variables. So perhaps your question could be modified to include some mention of your target SQL backend(s), and more about your specific SPARQL query/ies?
– TallTed
Mar 22 at 21:04
@TallTed Yes, of course I am trying to translate only a fragment of sparql into some generic SQL dialect. This however was not the main purpose of the question. I am not trying to find a method to translate a given sparql query, but given this method I already have, I am trying to be able to do it via Jena or some other library without rewriting everything.
– Valerio Colitta
Mar 22 at 21:13
@AKSW This is an idea, I could investigate, even though it wouldn't be really a clean solution. Thank you though
– Valerio Colitta
Mar 22 at 21:14
So, your question isn't about SPARQL nor SQL nor translating between them, but about some specific Java and Jena (or other Java library) programming challenge... Please edit the title and the body to make this clearer! The larger context of your immediate question is good to include, but that context should not appear to be the main focus.
– TallTed
Mar 22 at 21:27
|
show 2 more comments
I am trying to use Jena or some other Java library to achieve some coding challenge (in this case a rewriting through post-order traversal). I am not asking a methodology to translate SPARQL to SQL query. I already have that.
I am currently trying to translate a given SPARQL query into an some other SQL query.
So far, I've used Jena parser, that given a SPARQL query, returns an ARQ tree representation, that can be traversed in post-order. This is exactly what I want to do.
The only problem is that the Walker, just walks through the tree. What I would like to do, is something like this (suppose I am going through a MINUS) :
String visit(OpMinus minus)
String l_res = minus.getLeft().visit();
String r_res = minus.getRight().visit();
/*
... do some stuff with the result ...
*/
String res = l_res + "MINUS (" + r_res + ")";
return res;
Jena's visitor however returns void, making this impossible. Is there another way of doing it, instead of copying the Walker and the Visitor code, in order to make it work the way I want ? Thank you.
I am not looking for a SPARQL-to-SQL direct translator, because I need to work with the tree elements.
java parsing jena
edited Mar 22 at 21:54
TallTed
6,88521528
asked Mar 22 at 14:59
Valerio ColittaValerio Colitta
265
I am trying to use Jena or some other Java library to achieve some coding challenge (in this case a rewriting through post-order traversal). I am not asking a methodology to translate SPARQL to SQL query. I already have that.
I am currently trying to translate a given SPARQL query into an some other SQL query.
So far, I've used Jena parser, that given a SPARQL query, returns an ARQ tree representation, that can be traversed in post-order. This is exactly what I want to do.
The only problem is that the Walker, just walks through the tree. What I would like to do, is something like this (suppose I am going through a MINUS) :
String visit(OpMinus minus)
String l_res = minus.getLeft().visit();
String r_res = minus.getRight().visit();
/*
... do some stuff with the result ...
*/
String res = l_res + "MINUS (" + r_res + ")";
return res;
Jena's visitor however returns void, making this impossible. Is there another way of doing it, instead of copying the Walker and the Visitor code, in order to make it work the way I want ? Thank you.
I am not looking for a SPARQL-to-SQL direct translator, because I need to work with the tree elements.
java parsing jena
java parsing jena
edited Mar 22 at 21:54
TallTed
6,88521528
asked Mar 22 at 14:59
Valerio ColittaValerio Colitta
265
edited Mar 22 at 21:54
TallTed
6,88521528
asked Mar 22 at 14:59
Valerio ColittaValerio Colitta
265
edited Mar 22 at 21:54
TallTed
6,88521528
edited Mar 22 at 21:54
TallTed
6,88521528
edited Mar 22 at 21:54
TallTed
6,88521528
6,88521528
asked Mar 22 at 14:59
Valerio ColittaValerio Colitta
265
asked Mar 22 at 14:59
Valerio ColittaValerio Colitta
265
asked Mar 22 at 14:59
Valerio ColittaValerio Colitta
265
265
A walker does not return anything, butTransformerand theTransformclasses do.
– AKSW
Mar 22 at 17:35
Your question suggests a generalized translation, but that is not possible, because SPARQL and SQL have significant differences. Virtuoso performs such translations in different ways for different jobs. Translating "a given" (do you mean "any given" or "a specific"?) SPARQL query to "an equivalent" SQL query depends on the SQL schema(s), SQL dialects, SQL engines, and RDF ontology/ies in use, among other variables. So perhaps your question could be modified to include some mention of your target SQL backend(s), and more about your specific SPARQL query/ies?
– TallTed
Mar 22 at 21:04
@TallTed Yes, of course I am trying to translate only a fragment of sparql into some generic SQL dialect. This however was not the main purpose of the question. I am not trying to find a method to translate a given sparql query, but given this method I already have, I am trying to be able to do it via Jena or some other library without rewriting everything.
– Valerio Colitta
Mar 22 at 21:13
@AKSW This is an idea, I could investigate, even though it wouldn't be really a clean solution. Thank you though
– Valerio Colitta
Mar 22 at 21:14
So, your question isn't about SPARQL nor SQL nor translating between them, but about some specific Java and Jena (or other Java library) programming challenge... Please edit the title and the body to make this clearer! The larger context of your immediate question is good to include, but that context should not appear to be the main focus.
– TallTed
Mar 22 at 21:27
|
show 2 more comments
A walker does not return anything, butTransformerand theTransformclasses do.
– AKSW
Mar 22 at 17:35
Your question suggests a generalized translation, but that is not possible, because SPARQL and SQL have significant differences. Virtuoso performs such translations in different ways for different jobs. Translating "a given" (do you mean "any given" or "a specific"?) SPARQL query to "an equivalent" SQL query depends on the SQL schema(s), SQL dialects, SQL engines, and RDF ontology/ies in use, among other variables. So perhaps your question could be modified to include some mention of your target SQL backend(s), and more about your specific SPARQL query/ies?
– TallTed
Mar 22 at 21:04
@TallTed Yes, of course I am trying to translate only a fragment of sparql into some generic SQL dialect. This however was not the main purpose of the question. I am not trying to find a method to translate a given sparql query, but given this method I already have, I am trying to be able to do it via Jena or some other library without rewriting everything.
– Valerio Colitta
Mar 22 at 21:13
@AKSW This is an idea, I could investigate, even though it wouldn't be really a clean solution. Thank you though
– Valerio Colitta
Mar 22 at 21:14
So, your question isn't about SPARQL nor SQL nor translating between them, but about some specific Java and Jena (or other Java library) programming challenge... Please edit the title and the body to make this clearer! The larger context of your immediate question is good to include, but that context should not appear to be the main focus.
– TallTed
Mar 22 at 21:27
A walker does not return anything, but
Transformer and the Transform classes do.– AKSW
Mar 22 at 17:35
A walker does not return anything, but
Transformer and the Transform classes do.– AKSW
Mar 22 at 17:35
Your question suggests a generalized translation, but that is not possible, because SPARQL and SQL have significant differences. Virtuoso performs such translations in different ways for different jobs. Translating "a given" (do you mean "any given" or "a specific"?) SPARQL query to "an equivalent" SQL query depends on the SQL schema(s), SQL dialects, SQL engines, and RDF ontology/ies in use, among other variables. So perhaps your question could be modified to include some mention of your target SQL backend(s), and more about your specific SPARQL query/ies?
– TallTed
Mar 22 at 21:04
Your question suggests a generalized translation, but that is not possible, because SPARQL and SQL have significant differences. Virtuoso performs such translations in different ways for different jobs. Translating "a given" (do you mean "any given" or "a specific"?) SPARQL query to "an equivalent" SQL query depends on the SQL schema(s), SQL dialects, SQL engines, and RDF ontology/ies in use, among other variables. So perhaps your question could be modified to include some mention of your target SQL backend(s), and more about your specific SPARQL query/ies?
– TallTed
Mar 22 at 21:04
@TallTed Yes, of course I am trying to translate only a fragment of sparql into some generic SQL dialect. This however was not the main purpose of the question. I am not trying to find a method to translate a given sparql query, but given this method I already have, I am trying to be able to do it via Jena or some other library without rewriting everything.
– Valerio Colitta
Mar 22 at 21:13
@TallTed Yes, of course I am trying to translate only a fragment of sparql into some generic SQL dialect. This however was not the main purpose of the question. I am not trying to find a method to translate a given sparql query, but given this method I already have, I am trying to be able to do it via Jena or some other library without rewriting everything.
– Valerio Colitta
Mar 22 at 21:13
@AKSW This is an idea, I could investigate, even though it wouldn't be really a clean solution. Thank you though
– Valerio Colitta
Mar 22 at 21:14
@AKSW This is an idea, I could investigate, even though it wouldn't be really a clean solution. Thank you though
– Valerio Colitta
Mar 22 at 21:14
So, your question isn't about SPARQL nor SQL nor translating between them, but about some specific Java and Jena (or other Java library) programming challenge... Please edit the title and the body to make this clearer! The larger context of your immediate question is good to include, but that context should not appear to be the main focus.
– TallTed
Mar 22 at 21:27
So, your question isn't about SPARQL nor SQL nor translating between them, but about some specific Java and Jena (or other Java library) programming challenge... Please edit the title and the body to make this clearer! The larger context of your immediate question is good to include, but that context should not appear to be the main focus.
– TallTed
Mar 22 at 21:27
|
show 2 more comments
1 Answer
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active
oldest
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I eventually solved the problem by implementing my own Walker (since anything I am looking for is implemented in Jena) that traverses the tree in post-order and returns Strings
answered Mar 23 at 21:08
Valerio ColittaValerio Colitta
265
add a comment |
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I eventually solved the problem by implementing my own Walker (since anything I am looking for is implemented in Jena) that traverses the tree in post-order and returns Strings
answered Mar 23 at 21:08
Valerio ColittaValerio Colitta
265
add a comment |
I eventually solved the problem by implementing my own Walker (since anything I am looking for is implemented in Jena) that traverses the tree in post-order and returns Strings
answered Mar 23 at 21:08
Valerio ColittaValerio Colitta
265
add a comment |
I eventually solved the problem by implementing my own Walker (since anything I am looking for is implemented in Jena) that traverses the tree in post-order and returns Strings
answered Mar 23 at 21:08
Valerio ColittaValerio Colitta
265
I eventually solved the problem by implementing my own Walker (since anything I am looking for is implemented in Jena) that traverses the tree in post-order and returns Strings
answered Mar 23 at 21:08
Valerio ColittaValerio Colitta
265
answered Mar 23 at 21:08
Valerio ColittaValerio Colitta
265
answered Mar 23 at 21:08
Valerio ColittaValerio Colitta
265
answered Mar 23 at 21:08
Valerio ColittaValerio Colitta
265
265
add a comment |
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A walker does not return anything, but
Transformerand theTransformclasses do.– AKSW
Mar 22 at 17:35
Your question suggests a generalized translation, but that is not possible, because SPARQL and SQL have significant differences. Virtuoso performs such translations in different ways for different jobs. Translating "a given" (do you mean "any given" or "a specific"?) SPARQL query to "an equivalent" SQL query depends on the SQL schema(s), SQL dialects, SQL engines, and RDF ontology/ies in use, among other variables. So perhaps your question could be modified to include some mention of your target SQL backend(s), and more about your specific SPARQL query/ies?
– TallTed
Mar 22 at 21:04
@TallTed Yes, of course I am trying to translate only a fragment of sparql into some generic SQL dialect. This however was not the main purpose of the question. I am not trying to find a method to translate a given sparql query, but given this method I already have, I am trying to be able to do it via Jena or some other library without rewriting everything.
– Valerio Colitta
Mar 22 at 21:13
@AKSW This is an idea, I could investigate, even though it wouldn't be really a clean solution. Thank you though
– Valerio Colitta
Mar 22 at 21:14
So, your question isn't about SPARQL nor SQL nor translating between them, but about some specific Java and Jena (or other Java library) programming challenge... Please edit the title and the body to make this clearer! The larger context of your immediate question is good to include, but that context should not appear to be the main focus.
– TallTed
Mar 22 at 21:27