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https://github.com/chrdebru/r2rml


https://github.com/chrdebru/r2rml

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README 

        
# R2RML-F: an R2RML Implementation



## Building and using the code



Note: precompiled packages can be found [here](https://github.com/chrdebru/r2rml-distributions).



To build the project and copy its dependencies, execute



```bash

$ mvn clean

$ mvn package

$ mvn dependency:copy-dependencies

```



Note: in order to support connection to Oracle databases, we rely on a library that is not available from the Maven repository. If you have that library not installed manually, run `mvn clean` before `mvn package` and it will install the library locally prior to packaging. 



You can also avail of a compiled from that resides in the `dist` directory.



The run the R2RML processor, execute the following command:



```bash

$ java -jar r2rml.jar config.properties

```

A fat jar is also provided with the [Apache Maven Shade Plugin](https://maven.apache.org/plugins/maven-shade-plugin/). It does not depend on the `dependency` folder and can be executed as follows:



```bash

$ java -jar r2rml-fat.jar config.properties

```



Where `config.properties` is a properties file containing:



- `connectionURL`, a JDBC connection URL to a database (required)

- `user`, username for the user connecting to the database

- `password`, password for the user connecting to the database

- `mappingFile`, the R2RML mapping file (required)

- `outputFile`, the output file (required)

- `format`, format of the output files (default "TURTLE")

- `filePerGraph`, flag to write the different graphs in separate files (default "false")

- `baseIRI`, used in resolving relative IRIs produced by the R2RML mapping

- `CSVFiles`, a list of paths to CSV files that are separated by semicolons

- `prefixFile`, an RDF file from which name space prefixes will be reused.



When named graphs are used in the R2RML mapping, one should use serialization that support graphs such as N-QUADS and TRIG. The use of other serializations formats (such as TURTLE) results in all triples of all graphs being written away to that file. When setting the flag `filePerGraph` to `true` for serialization formats that do not support graphs, however, the value for `outputFile` will be used to create a directory in which a file will be created for each graph in the RDF dataset.



Note that you cannot use both `CSVFiles` and `connectionURL` at the same time. For each CSV file, the name of the table will be the base name of that file.



## Example



The directory `example` contains an example of a mapping and configuration file. The example assumes the MySQL database to be called `r2rml`, be running on `localhost` and accessible to the user `foo` with password `bar`. The configuration file looks as follows:



```properties

connectionURL = jdbc:mysql://localhost/r2rml

user = foo

password = bar

mappingFile = mapping.ttl

outputFile = output.ttl

format = TURTLE

```



The output, after passing the properties file as an argument to the R2RML processor, should look as follows:



```turtle



        a                              ;

          "SMITH" .

```



## Run with command line arguments



R2RML can be run with command line arguments similar to the configuration properties. 



```bash

$ java -jar r2rml.jar --connectionURL jdbc:mysql://localhost/r2rml \

  --user foo --password bar \

  --mappingFile mapping.ttl \

  --outputFile output.ttl \

  --format TURTLE

```



## Function with R2RML-F



This implementation of R2RML re-implemented the ideas presented in [1], allowing one to declare and use functions in ECMAScript as (Function Valued) TermMaps in the mapping. R2RML-F extends R2RML's vocabulary with predicates for declaring functions, function calls and parameter bindings. These are declared in the namespace [rrf](http://kdeg.scss.tcd.ie/ns/rrf/index.html).



```turtle

@prefix rr:  .

@prefix ex:  .

@prefix rrf: 



<#TriplesMap1>

    rr:logicalTable [ rr:tableName "EMP" ];

    rr:subjectMap [

        rr:template "http://data.example.com/employee/{EMPNO}";

        rr:class ex:Employee;

    ];

    rr:predicateObjectMap [

        rr:predicate ex:name;

        rr:objectMap [ rr:column "ENAME" ];

    ];

    rr:predicateObjectMap [

        rr:predicate ex:test;

        rr:objectMap [

	        rrf:functionCall [

	 			rrf:function <#Concat> ;

	 			rrf:parameterBindings (

	 				[ rr:column "ENAME" ]

	 				[ rr:column "EMPNO" ]

	 			) ;

	 		] ; 

	 	]

    ]    

    .

    

<#Concat>

	rrf:functionName "concat" ;

	rrf:functionBody """

		function concat(var1, var2) {

		return var1 + " " + var2 ;

	}

	""" ;

.

```



## License

This implementation of R2RML is written by [Christophe Debruyne](http://www.christophedebruyne.be/) and released under the [MIT license](http://opensource.org/licenses/MIT).



## References



[1]  C. Debruyne and D. O'Sullivan. R2RML-F: Towards Sharing and Executing Domain Logic in R2RML Mappings. In Proceedings of the Workshop on Linked Data on the Web, LDOW 2016, co-located with the 25th International World Wide Web Conference (WWW 2016), Montreal, Canada, April 12th, 2016, 2016