SPARQL router 0.4.0

The NodeJS/Express application that powers queery.link to serve canned SPARQL queries to the world.

master (demo)	develop (demo)

Description

SPARQL is the query language to retrieve data from RDF triple stores. I often had the issue that fellow developers or data fanatics asked for data that was in a triple store, but they don't know SPARQL.

This server application solves the issue:

1. You write the query and gives it a name (e.g. biggest-asian-cities)
2. You save it under /tables, /graphs or /update, depending on the query type (SELECT, CONSTRUCT, DESCRIBE, SPARQL Update)
3. You give the URL to your fellow developer, picking the right format for their usage:
   • http:/yourhost/api/tables/biggest-asian-cities.csv for manipulations as a spreadsheet
   • http:/yourhost/api/tables/biggest-asian-cities.json as input for a Web app
   • http:/yourhost/api/tables/biggest-asian-cities.xml if they are into XML
4. They get fresh updated results from the store every time they hit the URL!

Features

• Exposes SPARQL queries as simple URLs, with choice of result format
• A canned query is a simple file located in /public/api/tables, /public/api/graphs or /public/api/ask depending on the query type (SELECT, CONSTRUCT, DESCRIBE, SPARQL Update)
• Beside using FTP and SSH, you can POST a new canned query to /api/tables/{query-name}, /api/graphs/{query-name} or /api/ask/{query-name}
• For more query reuse, possibility to populate variable values in the query by passing parameters
• Supports content negotiation (via the Accept HTTP header)
• Possibility to GET or POST a SPARQL query on /api/sparql and get the results, without saving it

A screenshot of the tests as overview of the features.

Configuration and detailed usage documentation

Upcoming features

Known issues

Demo

• Master/stable: https://queery.link
• Develop/test: https://sparql-router.herokuapp.com

Requirements

• NodeJS (4.x, 5.x, 6.x) and NPM must be installed. They are also available in most Linux package managers as nodejs and npm.
• An RDF triple store that supports SPARQL 1.1 and JSON-LD output.

Installation

git clone https://github.com/ColinMaudry/sparql-router.git --depth=1
cd sparql-router
npm install --production

SPARQL router is also available as an NPM package.

Configuration

On the wiki.

Once it's configured, you must initialize the system queries and test queries:

npm run initialize

Test

I haven't found a proper way to mock a triple store for testing purposes. I consequently use a remote triple store. That means the tests only work if the machine has Internet access.

The configuration used for the tests is stored in config/test.json.

First, make sure, you have all the dev dependencies installed:

npm install

Tests rely on mocha and supertest for the API, and on nightwatch for the frontend.

API

To run the API tests:

npm test

Overview of the API tests.

Frontend

To run the frontend tests:

# Make sure the dev dependencies are installed
npm install

# Start the server in development mode with the test configuration
NODE_ENV=test npm run dev

# Run the frontend tests
npm run test-ui

Start it

Using config/default.json configuration file:

npm start

Using config/myconfig.json configuration file:

NODE_ENV=myconfig npm start

Start in debug mode:

DEBUG=functions,routes npm start

Resilient deployment

If you want the app to restart automatically after fatal errors, I suggest you use forever.

When forever is installed globally, run the following command in the sparql-router folder:

forever bin/www

Use it

See this wiki page for detailed instructions: Using SPARQL router

The API documentation can be found here (development version). If you're running the app, at /api.

Actions that require authentication

The actions that are not read-only on the canned queries or the data require basic authentication.

• HTTP PUT to create or update a query
• HTTP DELETE to delete a query

Similar software

If SPARQL router doesn't match your requirements, you can have a look at these solutions:

• The Datatank (PHP5) "The DataTank is open source software, which you can use to transform any dataset into an HTTP API."
• BASIL (Java) " BASIL is designed as middleware system that mediates between SPARQL endpoints and applications. With BASIL you can build Web APIs on top of SPARQL endpoints."

Contact

• Email: colin@maudry.com
• Twitter: @cmaudry / @queerylink

Change log

0.4.0

• User interface using Vue.js 1 and Bootstrap 3 (see https://queery.link)
  • @OpenTriply's YASQE as the editor (http://yasqe.yasgui.org/)
  • Table query results
  • Single page application (= very fast transitions)
• Possibility to delete a query
• Requesting .rq or application/sparql-query returns the query text instead of the query results

0.3.0

• An arbitrary endpoint can be passed with canned queries (upon creation or update) and with passthrough queries
• Metadata (name, author) can be passed with canned queries (new and updates) and with passthrough queries. Creation and modification dates are added automatically
• The system endpoint stores the canned queries metadata
• The default endpoint is the endpoint that is used if no endpoint is provided by the client
• Added support for ASK queries on /api/ask
• Started work on UI, using VueJS (just wireframes for now)
• Updated the API documentation accordingly

0.2.2

• Added extra info upon app startup (used config, endpoint, app URL, etc.)
• App authentication can be disabled in configuration
• README mentions the Datatank and BASIL alternatives
• Added an npm start command for commodity

0.2.1

• Improved installation instructions
• Added pictures to explain how this thing works
• Improved information about the demo

0.2.0

• Support for SPARQL Update queries (requires authentication)
• Possibility to populate query variable values via URL parameters! (#10)
• Queries created and updated via HTTP POST are tested before creation/update
• Possibility to setup user:password for the configured endpoint (Basic authentication)
• The URL of the query is returned when creating or updating a query
• Tested on Fuseki 2.x, Dydra, Stardog 4.0.5, OpenLink Virtuoso (LOD cache)
• More useful error messages
• Applied NodeJS security best practices (with helmet)

0.1.0

• Enabled canned queries
• Extension (.csv, .xml, etc.) defines the format returned by the endpoint
• Passthrough queries via /sparql
• Create new canned queries by HTTP POST, SSH or FTP
• Basic auth for POST and DELETE
• API doc written in Swagger
• Support for HTTPS endpoints
• CORS support

License

MIT license

If you use it, I'd really appreciate a public statements such as a tweet!