meacial001 / neosemantics

Experiments bridging the RDF and LPG worlds.

neosemantics

Installation

You can either download a prebuilt jar from the releases area or build it from the source. If you prefer to build, check the note below.

1. Copy the the jar(s) in the <NEO_HOME>/plugins directory of your Neo4j instance. If present, remember to remove APOC from this folder as it is already bundled with neosemantics.
2. Add the following line to your <NEO_HOME>/conf/neo4j.conf

dbms.unmanaged_extension_classes=semantics.extension=/rdf

3. Restart the server.
4. Check that the installation went well by running call dbms.procedures(). The list of procedures should include the ones documented below. You can check that the extension is mounted by running :GET /rdf/ping

Note on build

When you run

mvn clean package

This will produce two jars :

1. A neosemantics-[...].jar This jar bundles all the dependencies and also apoc. So if apoc is already in your plugins directory, remember to remove it to avoid conflicts.
2. An original-neosemantics-[...].jar This jar is just the neosemantics bit. So go this way if you want to keep the third party jars separate. In this case you will have to add APOC and all third party dependencies (look at the pom.xml).

What's in this repository

This repository contains a set of stored procedures and extensions to both produce and consume RDF from Neo4j.

Stored Procedures

Stored Proc Name	params	Description and example usage
semantics.importRDF	URL of the dataset serialization format(*) map with zero or more params (see table below)	Imports into Neo4j all the triples in the data set according to [the mapping defined in this post] (https://jesusbarrasa.wordpress.com/2016/06/07/importing-rdf-data-into-neo4j/). Note that before running the import procedure an index needs to be created on property uri of Resource nodes. Just run CREATE INDEX ON :Resource(uri) on your Neo4j DB. Examples: CALL semantics.importRDF("file:///.../myfile.ttl","Turtle", { shortenUrls: false, typesToLabels: true, commitSize: 9000 }) CALL semantics.importRDF("http:///.../donnees.rdf","RDF/XML", { languageFilter: 'fr', commitSize: 5000 , nodeCacheSize: 250000})
semantics.previewRDF	URL of the dataset serialization format(*) map with zero or more params (see table below)	Parses some RDF and produces a preview in Neo4j browser. Same parameters as data import except for periodic commit, since there is no data written to the DB. Notice that this is adequate for a preliminary visual analysis of a SMALL dataset. Think how many nodes you want rendered in your browser. Examples: CALL semantics.previewRDF("https://.../clapton.n3","Turtle", {})
semantics.previewRDFSnippet	An RDF snippet serialization format(*) map with zero or more params (see table below)	Identical to previewRDF but takes an RDF snippet instead of the url of the dataset. Again, adequate for a preliminary visual analysis of a SMALL dataset. Think how many nodes you want rendered in your browser :) Examples: CALL semantics.previewRDFSnippet('[{"@id": "http://indiv#9132", "@type": ... }]', "JSON-LD", { languageFilter: 'en'})
semantics.liteOntoImport	URL of the dataset serialization(*)	Imports the basic elements of an OWL or RDFS ontology, i.e. Classes, Properties, Domains, Ranges. Extended description here Example: CALL semantics.liteOntoImport("http://.../myonto.trig","TriG")

(*) Valid formats: Turtle, N-Triples, JSON-LD, TriG, RDF/XML

Param	values(default)	Description
shortenUrls	boolean (true)	when set to true, full urls are shortened using generated prefixes for both property names, relationship names and labels
typesToLabels	boolean (true)	when set to true, rdf:type statements are imported as node labels in Neo4j
languageFilter	['en','fr','es',...]	when set, only literal properties with this language tag (or untagged ones) are imported
commitSize	integer (25000)	commit a partial transaction every n triples
nodeCacheSize	integer (10000)	keep n nodes in cache to minimize reads from DB

Extensions

Extension	params	Description and example usage
/rdf/describe/id	nodeid:the id of a node excludeContext:(optional) if present output will not include connected nodes, just selected one.	Produces an RDF serialization of the selected node. The format will be determined by the accept parameter in the header. Default is JSON-LD Example: :GET /rdf/describe/id?nodeid=0&excludeContext
/rdf/describe/uri	nodeuri:the uri of a node excludeContext:(optional) if present output will not include connected nodes, just selected one.	Produces an RDF serialization of the selected node. It works on a model either imported from an RDF dataset via semantics.importRDF or built in a way that nodes are labeled as :Resource and have an uri. This property is the one used by this extension to lookup a node. Example: :GET /rdf/describe/uri?nodeuri=http://dataset.com#id_1234
/rdf/cypher	Takes a cypher query in the payload	Produces an RDF serialization of the nodes and relationships returned by the query. Example: :POST /rdf/cypher "MATCH (a:Type1)-[r:REL]-(b) RETURN a, r, b"
/rdf/cypheronrdf	Takes a cypher query in the payload	Produces an RDF serialization of the nodes and relationships returned by the query. It works on a model either imported from an RDF dataset via semantics.importRDF or built in a way that nodes are labeled as :Resource and have an uri. Example: :POST /rdf/cypheronrdf "MATCH (a:Resource {uri:'http://dataset/indiv#153'})-[r]-(b) RETURN a, r, b"