GeoTriples

Publishing geospatial data as Linked Geospatial Data. GeoTriples generates and processes extended R2RML and RML mappings that transform geospatial data from many input formats into RDF. GeoTriples allows the transformation of geospatial data stored in raw files (shapefiles, CSV, KML, XML, GML and GeoJSON) and spatially-enabled RDBMS (PostGIS and MonetDB) into RDF graphs using well-known vocabularies like GeoSPARQL and stSPARQL, but without being tightly coupled to a specific vocabulary.

Quickstart

Use GeoTriples binaries (Unix)

Assuming Java 8 is installed:

Download GeoTriples binaries from here

• Unzip the downloaded file geotriples-<version>-bin.zip
• Change directory to geotriples-<version>-bin
• Under the bin directory you can find the available starter script for GeoTriples

Generate Mapping files:

bin/geotriples-all generate_mapping -o <output_file (.ttl)> -b <URI base> <input file>

Transform file into RDF

bin/geotriples-all dump_rdf -o <output_file> -b http://example.com (-sh <shp file>) <path_to_the_mapping_file (.ttl)>

See more at Wiki pages

Execution by source

Clone this repository and install the source code by using

mvn package 

Generate Mapping files:

java -cp <geotriples-core/ dependencies jar> eu.linkedeodata.geotriples.GeoTriplesCMD generate_mapping -o <output file(.ttl)> -b <URI base> <input file>

• -o output_file the name of the produced mapping file (RML/R2RML)
• -b URI_base the base URI that will describe the entities
• use the option -rml to force the generation of an RML file

Transform file into RDF

java -cp <geotriples-core/ dependencies jar> eu.linkedeodata.geotriples.GeoTriplesCMD dump_rdf -o <output file> -b <URI base> (-sh <shp file>) (-rml) <(produced) mapping file (.ttl)>

• -o output_file the path of the produced file
• -b URI_base the base URI that will describe the entities
• -sh shp_file if the input is a shapefile specify the .shp path using this flag
• use the -rml option if the input mapping file is expected to be an RML file, required for CSV files

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GeoTriples-Spark

GeoTriples-Spark is an extended version of GeoTriples capable of transforming big geospatial data into RDF graphs. To enable the transformation of big geospatial data, we extended GeoTriples to run on top of Apache Spark and Hadoop or Hops (a new distribution of Apache Hadoop developed by KTH, RISE SICS, and Logical Clocks AB). GeoTriples-Spark can run in a standalone machine or in a Hadoop based cluster, but it is more efficient when it runs on Hops as it is a write-intensive application. GeoTriples-Sparks supports the transformation of CSV, GeoJSON and Shapefiles. You can examine the performance of GeoTriples-Spark in ISWC-experiments

Requirements

• Java 8
• Maven 3
• Apache Spark 2.4.0 or greater
• Apache Hadoop 2.7.0 or Hops

Build

mvn package

Execute

spark-submit --class eu.linkedeodata.geotriples.GeoTriplesCMD <geotriples-core/ dependencies jar> spark -i <in_file> -o <out_folder> <rml>

• -i input_file: path to input dataset. You can enter multiple files, separated by ","

• -o out_folder: path to the folder where the results will be stored. In case the folder exists, a new folder inside it will be created.

• The rml indicates to the RML mapping file, produced by the generate_mapping procedure of GeoTriples.

Additional flags

• -m mode: set the transformation mode. It can be either partition or row (default mode). In the partition mode the RDF triples are written to the target file after the transformation of the whole partition. In the row mode, each record is transformed into RDF triples which are directly written to the target files. For small datasets the partition mode is faster, but we advise to use the row mode as it is more memory friendly.

• -r partitions: re-partition the input dataset. WARNING re-partitionig triggers data shuffling and therefore it can negative effects in the performance.

• -sh folder_path: Load multiple ESRI shapefiles, that exist in the folder_path (each one must be stored in a separate folder). For example the structure of the folder must look like:

    folder_path/shapefile1/shapefile1.(shp, dbf, shx, etc)
    folder_path/shapefile2/shapefile2.(shp, dbf, shx, etc)
    ...
  

  For each Shapefile, a different RDF dataset will be created. Furthermore, the RML mapping file must support all the input datasets.

• -times n: Load the input dataset "n" times.

• help: Print instrcuctions