Setting up a SPARQL endpoint
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The SPARQL protocol allows clients to send SPARQL queries to Web servers over HTTP, and query results to be sent back to the client. Comunica SPARQL can be used to set up a SPARQL endpoint on top of any number of sources you want.
1. Installation
Since Comunica runs on Node.js, make sure you have Node.js installed on your machine.
Next, we can install Comunica SPARQL on our machine:
$ npm install -g @comunica/query-sparql
2. SPARQL endpoint over one source
After installing Comunica SPARQL, you will be given access to several commands including comunica-sparql-http,
which allows you to start a SPARQL endpoint from the command line.
This command requires one or more URLs to be provided as sources to query over.
For example, the following command starts a SPARQL endpoint over DBpedia:
$ comunica-sparql-http https://fragments.dbpedia.org/2016-04/en
By default, the endpoint will be exposed on port 3000.
Your endpoint will now be live on http://localhost:3000/sparql.
Any client that understands the SPARQL protocol will now be able to send queries to this URL,
such as fetch-sparql-endpoint, or even Comunica itself.
http://localhost:3000/ will automatically redirect to http://localhost:3000/sparql.
You can easily test query execution over your endpoint using a tool such as curl.
The SPARQL protocol allows sending queries via HTTP GET by passing a URL-encoded SPARQL query via the ?query= parameter:
$ curl -v "http://localhost:3000/sparql?query=CONSTRUCT%20WHERE%20%7B%3Fs%20%3Fp%20%3Fo.%7DLIMIT%20100"
3. SPARQL endpoint over multiple sources
One key feature of Comunica is its ability to query over multiple sources. For this, you can just supply any number of URLs as arguments.
$ comunica-sparql-http https://fragments.dbpedia.org/2016-04/en \ https://www.rubensworks.net/ \ https://ruben.verborgh.org/profile/
4. SPARQL endpoint over local files
First install Comunica SPARQL for files:
$ npm install -g @comunica/query-sparql-file
Then start the SPARQL server:
$ comunica-sparql-file-http path/to/my/file.ttl
5. Changing the port
Using the -p option, the port can be changed:
$ comunica-sparql-http https://fragments.dbpedia.org/2016-04/en \ -p 3001
6. Increasing the number of worker threads
Using the -w option, the number of parallel worker threads can be set:
$ comunica-sparql-http https://fragments.dbpedia.org/2016-04/en \ -w 4
Setting this to the number of available CPU cores tends to give the best performance.
7. Adding a context
Using the -c option, you can add a context (JSON string or file):
$ comunica-sparql-http -c config.json
config.json could look like this:
{ "sources": [ "https://fragments.dbpedia.org/2016-04/en" ], "lenient": true }
8. Emitting VoID metadata
Using --emitVoid you can make your endpoint include a VoID description in its service description:
$ comunica-sparql-http -c config.json --emitVoid
The metadata can be found in the service description at http://localhost:3000/sparql.
You can also add Dublin Core Metadata Terms (general metadata) using a dcterms field in the context:
{ "sources": [ "https://www.rubensworks.net/", "https://ruben.verborgh.org/profile/" ], "dcterms": { "title": "My Comunica SPARQL Endpoint", "description": "This is a SPARQL endpoint powered by Comunica", "creator": "https://rubensworks.net/#me", "created": "2025-08-07" } }
The service description with VoID included for the above context will look like this:
</sparql> a <http://www.w3.org/ns/sparql-service-description#Service>; <http://www.w3.org/ns/sparql-service-description#endpoint> </sparql>; <http://www.w3.org/ns/sparql-service-description#url> </sparql>; <http://www.w3.org/ns/sparql-service-description#feature> <http://www.w3.org/ns/sparql-service-description#BasicFederatedQuery>; <http://www.w3.org/ns/sparql-service-description#supportedLanguage> <http://www.w3.org/ns/sparql-service-description#SPARQL10Query>, <http://www.w3.org/ns/sparql-service-description#SPARQL11Query>; <http://www.w3.org/ns/sparql-service-description#resultFormat> <https://comunica.linkeddatafragments.org/#results_stats>, <http://www.w3.org/ns/formats/SPARQL_Results_JSON>, <http://www.w3.org/ns/formats/Shaclc>, <http://www.w3.org/ns/formats/ShaclcExtended>, <http://www.w3.org/ns/formats/JSON-LD>, <http://www.w3.org/ns/formats/N-Quads>, <http://www.w3.org/ns/formats/N-Triples>, <http://www.w3.org/ns/formats/TriG>, <http://www.w3.org/ns/formats/N3>, <http://www.w3.org/ns/formats/Turtle>, <https://comunica.linkeddatafragments.org/#results_tree>, <https://comunica.linkeddatafragments.org/#results_table>, <http://www.w3.org/ns/formats/SPARQL_Results_XML>, <http://www.w3.org/ns/formats/SPARQL_Results_TSV>, <http://www.w3.org/ns/formats/SPARQL_Results_CSV>, <https://comunica.linkeddatafragments.org/#results_simple>, <https://comunica.linkeddatafragments.org/#results_JSON>; <http://www.w3.org/ns/sparql-service-description#defaultDataset> _:defaultDataset. _:defaultDataset a <http://www.w3.org/ns/sparql-service-description#Dataset>, <http://rdfs.org/ns/void#Dataset>; <http://rdfs.org/ns/void#sparqlEndpoint> </sparql>; <http://rdfs.org/ns/void#vocabulary> <http://purl.org/dc/terms/>; <http://purl.org/dc/terms/title> "My Comunica SPARQL Endpoint"; <http://purl.org/dc/terms/description> "This is a SPARQL endpoint powered by Comunica"; <http://purl.org/dc/terms/creator> <https://rubensworks.net/#me>; <http://purl.org/dc/terms/created> "2025-08-07"^^<http://www.w3.org/2001/XMLSchema#date>; <http://www.w3.org/ns/sparql-service-description#defaultGraph> _:defaultGraph. _:defaultGraph a <http://www.w3.org/ns/sparql-service-description#Graph>; <http://rdfs.org/ns/void#classes> 19. _:defaultDataset <http://rdfs.org/ns/void#classPartition> _:classPartition0. _:classPartition0 a <http://rdfs.org/ns/void#ClassPartition>; <http://rdfs.org/ns/void#class> <http://xmlns.com/foaf/0.1/Person>; <http://rdfs.org/ns/void#entities> 438. _:defaultDataset <http://rdfs.org/ns/void#classPartition> _:classPartition1. _:classPartition1 a <http://rdfs.org/ns/void#ClassPartition>; <http://rdfs.org/ns/void#class> <http://xmlns.com/foaf/0.1/Document>; <http://rdfs.org/ns/void#entities> 1. ... _:defaultDataset <http://rdfs.org/ns/void#classPartition> _:classPartition18. _:classPartition18 a <http://rdfs.org/ns/void#ClassPartition>; <http://rdfs.org/ns/void#class> <http://www.w3.org/2002/07/owl#AllDifferent>; <http://rdfs.org/ns/void#entities> 1. _:defaultDataset <http://rdfs.org/ns/void#propertyPartition> _:propertyPartition0. _:propertyPartition0 a <http://rdfs.org/ns/void#PropertyPartition>; <http://rdfs.org/ns/void#property> <http://xmlns.com/foaf/0.1/primaryTopic>; <http://rdfs.org/ns/void#triples> 8. _:defaultDataset <http://rdfs.org/ns/void#propertyPartition> _:propertyPartition1. _:propertyPartition1 a <http://rdfs.org/ns/void#PropertyPartition>; <http://rdfs.org/ns/void#property> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>; <http://rdfs.org/ns/void#triples> 901. ... _:defaultDataset <http://rdfs.org/ns/void#propertyPartition> _:propertyPartition9. _:propertyPartition9 a <http://rdfs.org/ns/void#PropertyPartition>; <http://rdfs.org/ns/void#property> <http://xmlns.com/foaf/0.1/name>; <http://rdfs.org/ns/void#triples> 80. _:defaultGraph <http://rdfs.org/ns/void#triples> 11542; <http://rdfs.org/ns/void#entities> 5701; <http://rdfs.org/ns/void#distinctSubjects> 3714; <http://rdfs.org/ns/void#properties> 79; <http://rdfs.org/ns/void#distinctObjects> 5646. _:defaultDataset <http://rdfs.org/ns/void#propertyPartition> _:propertyPartition10. _:propertyPartition10 a <http://rdfs.org/ns/void#PropertyPartition>; <http://rdfs.org/ns/void#property> <http://ogp.me/ns#site_name>; <http://rdfs.org/ns/void#triples> 1. ... _:defaultDataset <http://rdfs.org/ns/void#propertyPartition> _:propertyPartition78. _:propertyPartition78 a <http://rdfs.org/ns/void#PropertyPartition>; <http://rdfs.org/ns/void#property> <http://www.w3.org/2002/07/owl#distinctMembers>; <http://rdfs.org/ns/void#triples> 1.
9. Learn more
This guide only discussed the basic functionality of comunica-sparql-http.
You can learn more options by invoking the help command:
$ comunica-sparql-http --help comunica-sparql-http exposes a SPARQL endpoint Recommended options: -p, --port HTTP port to run on [number] [default: 3000] -w, --workers Number of worker threads [number] [default: 1] -t, --timeout Query execution timeout in seconds [number] [default: 60] -u, --update Enable update queries (otherwise, only read queries are enabled) [boolean] Options: -c, --context Use the given JSON context string or file (e.g., config.json) [string] --to Destination for update queries [string] -b, --baseIRI base IRI for the query (e.g., http://example.org/) [string] --fileBaseIRI base IRI for the file (e.g., http://example.org/), useful when using comunica-sparql-file [string] -d, --dateTime Sets a datetime for querying Memento-enabled archives [string] -l, --logLevel Sets the log level (e.g., debug, info, warn, ...) [string] [default: "warn"] --lenient If failing requests and parsing errors should be logged instead of causing a hard crash [boolean] -v, --version Prints version information [boolean] --showStackTrace Prints the full stacktrace when errors are thrown [boolean] --httpTimeout HTTP requests timeout in milliseconds [number] --httpBodyTimeout Makes the HTTP timeout take into account the response body stream read [boolean] --httpRetryCount The number of retries to perform on failed fetch requests [number] --httpRetryDelayFallback The fallback delay in milliseconds between fetch retries [number] --httpRetryDelayLimit The upper limit in milliseconds for the delay between fetch retries [number] --unionDefaultGraph If the default graph should also contain the union of all named graphs [boolean] -i, --invalidateCache Enable cache invalidation before each query execution [boolean] --distinctConstruct If the query engine should deduplicate resulting triples [boolean] --freshWorker Kills the worker after each query execution [boolean] --contextOverride If the query context can be overridden through POST requests [boolean] --emitVoid Generate VoID descriptions and include them in the service description [boolean] Examples: comunica-sparql-http https://fragments.dbpedia.org/2016-04/en comunica-sparql-http https://fragments.dbpedia.org/2016-04/en https://query.wikidata.org/sparql comunica-sparql-http hypermedia@https://fragments.dbpedia.org/2016-04/en sparql@https://query.wikidata.org/sparql