FROST : RDF Triple Store with a SPARQL Query Engine

Version

　 1.1.0

Abstract

　 FROST is a fast in-memory RDF database system that compactly stores RDF triples.

　 Download

Example

RDF Data

<http://example.com/Woman> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <http://example.com/Human> .
<http://example.com/Man> <http://www.w3.org/2000/01/rdf-schema#subClassOf> <http://example.com/Human> .
<http://example.com/Alice> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://example.com/Woman> .
<http://example.com/Alice> <http://example/Properties#name> "Alice" .
<http://example.com/Alice> <http://example/Properties#age> "20" .
<http://example.com/Bob> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://example.com/Man> .
<http://example.com/Bob> <http://example/Properties#name> "Bob" .
<http://example.com/Bob> <http://example/Properties#knows> <http://example.com/Alice> .
<http://example.com/Bob> <http://example/Properties#age> "21" .

Query1

#Query to search the name of the known female of Bob
PREFIX ex: <http://example.com/>
PREFIX prop: <http://example/Properties#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT * WHERE{ex:Bob prop:knows ?x .?x rdf:type ex:Woman .?x prop:name ?y .}
C:FROST>frost --data sample.nt --query query1.rq
----------------------------------------
| x                          | y       |
========================================
| <http://example.com/Alice> | "Alice" |
----------------------------------------

Query2

#Query to search the resources of distance 2 from Bob
PREFIX ex: <http://example.com/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT ?o1 ?o2 WHERE{ex:Bob ?p1 ?o1 .?o1 ?p ?o2 .}
C:FROST>frost --data sample.nt --query query2.rq
-----------------------------------------------------------
| o1                         | o2                         |
===========================================================
| <http://example.com/Alice> | "Alice"                    |
| <http://example.com/Alice> | <http://example.com/Woman> |
| <http://example.com/Man>   | <http://example.com/Human> |
-----------------------------------------------------------

Query3

#Query to search the type of Bob
PREFIX ex: <http://example.com/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT * WHERE{ex:Bob rdf:type ?x .}
C:FROST>frost --data sample.nt --query query3.rq
----------------------------
| x                        |
============================
| <http://example.com/Man> |
----------------------------

You can select the inference mode with the following option.
C:FROST>frost --data sample.nt --query query3.rq -inf
------------------------------
| x                          |
==============================
| <http://example.com/Man>   |
| <http://example.com/Human> |
------------------------------

Query4

PREFIX ex: <http://example.com/>
PREFIX prop: <http://example/Properties#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT * WHERE{?person rdf:type ex:Human .?person prop:name ?name .
                       ?person prop:age ?age .FILTER(?age >= 20 && REGEX(?name,"l"))}
C:FROST>frost --data sample.nt --query query4.rq -inf
-----------------------------------------------
| person                     | name    | age  |
===============================================
| <http://example.com/Alice> | "Alice" | "20" |
-----------------------------------------------

System Requirement

Java 7 or later.

Usage

java -jar frost.jar --data <data_name> --query <query_name> [-options]
<data_name>N-Triples file
<query_name>Query file

You can use a batch file as follows.
frost --data <data_name> --query <query_name> [-options]

Options

-version Print version
-help Print help
--result csv Output with csv(faster than default format)
-inf Inference mode
-once
-comp More compress mode
--ld num Divide load (num split)

Index data is generated in folder(temporarydata) under current directory after FROST executed.
You delete the index data and execute FROST if you change inference mode or not.

Query

FROST supports a restricted query syntax of SPARQL.
You can see some examples of SELECT queries in the zipped file.

Syntax

Query ::= Prologue SelectQuery
Prologue ::= PrefixDecl*
PrefixDecl ::= 'PREFIX' PNAME_NS IRI_REF
SelectQuery ::= 'SELECT' ( Var+ | '*' ) WhereClause SolutionModifier
WhereClause ::= 'WHERE'? GroupGraphPattern
SolutionModifier ::= LimitOffsetClauses*
GroupGraphPattern ::= '{' TripleBlock? ('.' TripleBlock? )* '}'
TripleBlock ::= VarOrTerm ' ' VarOrTerm ' ' VarOrTerm


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