SPARQL to SQL Project

This project aims to create a Java Spring parser that can convert SPARQL queries into SQL queries. The project is part of the BD team's research efforts within the LIRIS and VCity project. The aim of this POC is to query a set of city version and extract associated knowledge.

Getting started

Installation

This project uses Java 17 JDK + Maven and a dockerized (make sure that Docker is installed too) PostgreSQL 15 database. If you don't have Java 17 installed by default, I recommend that you install SDKMAN! and use this tool to set Java 17 as current session version.

SDKMAN! is a tool for managing parallel versions of multiple Software Development Kits on most Unix based systems.

Once you have SDKMAN! installed, run:

sdk install java 17.0.7-amzn
sdk use java 17.0.7-amzn

Make sure you have Maven installed. If you don't have Maven installed, run: sudo apt install maven.

Maven dependencies

This project uses:

• the jena-arq 4.8.0 library for parsing SPARQL statements in Java,
• the springdoc-openapi-starter-webmvc-ui 2.1.0 library to parse the Swagger API annotations and displays the swagger-ui,
• a Dockerized PostgreSQL 15 database, so the postgresql driver is installed too.

Start the application

Dockerized database + Java Spring

# at the root of the project
# starts the database declared inside the docker-compose.yml file
docker compose up -d

# wait until the PostgreSQL database is up
# starts the Java Spring application locally (http://localhost:8080/)
mvn spring-boot:run 

Implementation

Entity–Relationship model

erDiagram
    VersionedQuad |{--|| ResourceOrLiteral: extends
    VersionedQuad |{--|| NamedGraph: extends
    VersionedQuad |{--|| Commit: extends
    VersionedQuad {
        int id_subject PK, FK
        int id_property PK, FK
        int id_object PK, FK
        int id_named_graph FK
        bitstring validity
    }
    NamedGraph {
        int id_named_graph PK, FK
        int name
    }
    ResourceOrLiteral {
        int id_resource_or_literal PK, FK
        Text name
        string type "Not null if literal"
    }
    Commit {
        int id_commit PK, FK
        Varchar(255) message
        timestamptz date_commit
    }

Flowcharts

Query the relational database with a SPARQL query

flowchart LR
    CS[Computer Scientist] --> |Sends the SPARQL query to the endpoint| SE
    SE --> |Sends the quads to the Computer Scientist| CS 
    subgraph Server
        SE --> |Sends the SPARQL query for translation| ARQ[Jena ARQ]
        ARQ --> |Sends the SQL translated query to JDBC| JDBC[Java Database Connectivity]
        JDBC --> |The filtered quads| ARQ
        ARQ --> |The filtered quads| SE
        
    end
    subgraph Database
        JDBC --> |Sends the SQL query to the database| DB[PostgreSQL]
        DB --> |Sends the result of the SQL query| JDBC
    end

Store RDF quads inside a relational database

flowchart LR
    CS[Computer Scientist] --> |Sends the files to the import endpoint| SE
    subgraph Server
        SE --> |Sends files to import| RIOT[Jena RIOT]
        RIOT --> |Send the quads for insertion| JDBC[Java Database Connectivity]        
    end
    subgraph Database
        JDBC --> |Sends the SQL query to the database| DB[PostgreSQL]
    end

Testing

The API description is available on the swagger-ui at runtime.

# make sure your database is up

# starts the tests
mvn spring-boot:run test