virtuoso-connector v1.0.3

🔗 virtuoso-connector

Package that allows you to create a direct connection to the Virtuoso database and run queries on it. Connection can be used to execute both SQL and SPARQL queries, or even internal database stored procedures.

ℹ Background

Since there is no native Virtuoso driver for NodeJS, the only option is to use Java bindings, which enables communication between a JDBC driver and a NodeJS application.

The @naxmefy/jdbc package provides support for communication with the JDBC driver, which is appropriate because Virtuoso provides a JDBC driver and thus they can be used together. The only disadvantage of this approach is that the process needs to start JVM and whenever it crashes, it crashes the whole application. To prevent the crash of the whole application, the DatabaseConnection manages a pool of child processes (forks) (DatabaseConnectionChild) which are responsible for the queries execution.

Selection of the child process is made by Round Robin load balancing mechanism. Delegation of the execution is done in the form of sending messages through the IPC channel, with a unified interface defined in types.ts file. Once the query inside the message is being resolved by the child process, it sends a new message with the response back to the service. In case of a crash of the JVM, for instance, due to the broken connection with the database or segmentation fault, the child will be terminated and deleted from the pool. Because the child processes are detached from the parent, they do not crash the application, but only themselves.

⭐️ Features

• connection pool,
• support of SPARQL query builder syntax (@tpluscode/rdf-string, @tpluscode/sparql-builder),
• support for executing stored procedures or even SQL

🚀 Installation

yarn add virtuoso-connector

npm install virtuoso-connector

Note: Install peer dependencies if needed

🤘🏻 Usage

import { DatabaseConnection } from 'virtuoso-connector'

const db = new DatabaseConnection({
  url: 'jdbc:virtuoso://127.0.0.1:1111/CHARSET=UTF-8',
  username: 'dba',
  password: 'dba',
  driverPath: '/usr/local/vos/lib/jdbc-4.2/virtjdbc4_2.jar',
  lazy: false,
  maxQueryTimeout: 360, // optional (in seconds), 0 = unlimited
  poolSize: 2 // max active connections
})

const results = await db.query(`
  SELECT ?s ?p ?o 
  WHERE { ?s ?p ?o }
  LIMIT 10
`)

results.forEach(result => {
  console.info(result.s, result.p, result.o)
})

// Destroy connection
db.destroy()

// Example preview of results (with LIMIT 1)
[{
  s: NamedNode {
    termType: 'NamedNode',
    value: 'http://www.openlinksw.com/virtrdf-data-formats#default-iid'
  },
  p: NamedNode {
    termType: 'NamedNode', 
    value: 'http://www.w3.org/1999/02/22-rdf-syntax-ns#type'
  },
  o: NamedNode {
    termType: 'NamedNode',
    value: 'http://www.openlinksw.com/schemas/virtrdf#QuadMapFormat'
  } 
}]