rdflib.js Documentation

"Smushing" is the process of merging identifiers that are stated to denote the same thing. By default, rdflib stores perform no smushing. You must opt-in when creating the graph.

To enable smushing for owl:sameAs, owl:InverseFunctionalProperty, and owl:FunctionalProperty, pass the feature names to the $rdf.graph() constructor:

const kb = $rdf.graph(['sameAs', 'InverseFunctionalProperty', 'FunctionalProperty'])

How Smushing Works

• Equivalence: When A owl:sameAs B is added, the store chooses one node as canonical and re-indexes all statements under it. Queries for either identifier will return the merged data.
• Internal Book-keeping: The store records the equivalence using the http://www.w3.org/2007/ont/link#uri namespace. It adds a statement: <canonical> <http://www.w3.org/2007/ont/link#uri> <obsoleted> .
• Discovery: You can use store.uris(term) and store.allAliases(node) to list identifiers. If a Fetcher is attached, equating nodes triggers a look-up of the newly-learned alias.
• Metadata: The Fetcher also uses the http://www.w3.org/2007/ont/link# namespace to record HTTP metadata (requests, responses, status codes) in a separate metadata graph. This can be cleared using store.removeMetadata(doc).

The UpdateManager selects an update method based on the server's response headers.

For Non-http(s) URIs

• N3PATCH: Used if the accept-patch header's mime-essence is text/n3.
• SPARQL PATCH: Used if the response contains accept-patch or ms-author-via headers.
• PUT: Used as the fallback method.

For Http(s) URIs

• N3PATCH: Used if the accept-patch header's mime-essence is text/n3.
• SPARQL PATCH: Used if:
  • accept-patch is application/sparql-update
  • accept-patch is application/sparql-update-single-match
  • ms-author-via contains the word SPARQL
• PUT: Used if the ms-author-via header contains the word DAV.

Important Implementation Notes

• N3-PATCH Support: Currently, rdflib does not support N3-PATCH updates, even though it is mentioned in specifications.
• PATCH vs PUT: When submitting a form, PATCH is used by default. However, PUT is used specifically when re-ordering elements in an ordered list.

By default, rdflib uses cross-fetch.fetch(), which does not carry authentication information. To access private data (e.g., Solid pods) or use custom fetch implementations (e.g., Dropbox, databases), you can override the global fetch method used by rdflib.

Steps to implement:

1. Load your authentication library.
2. Log in to your identity provider using that library.
3. Assign the library's fetch method to the global fetch variable:
   • In a Browser: Set window.solidFetch.
   • In Node.js/CLI: Set global.solidFetch.

Note on version compatibility:

• For rdflib version 2.2.9 and later: Use solidFetch.
• For rdflib prior to 2.2.9: Use solidFetcher.

// Node.js Example
const auth = new (require("solid-node-client").SolidNodeClient)();
await auth.login( credentials );
global.solidFetch = auth.fetch; 

const $rdf = global.$rdf = require('rdflib');
const kb = $rdf.graph();
const fetcher = $rdf.fetcher(kb);
await fetcher.load( 'https://some-private-url' );

To use authenticated Solid data in a browser environment, use a library like @inrupt/solid-client-authn-browser. You must handle the OIDC login redirect and then set window.solidFetcher (or window.solidFetch for newer versions) to the library's fetch method before performing rdflib operations.

<!-- Simplified Browser Implementation Pattern -->
<script src="https://cdn.jsdelivr.net/npm/@inrupt/solid-client-authn-browser@1.11.2/dist/solid-client-authn.bundle.js"></script>
<script src="https://cdn.jsdelivr.net/npm/rdflib@2.2.6/dist/rdflib.min.js"></script>

<script>
    const idp = "https://solidcommunity.net";
    const privateResource = "https://jeff-zucker.solidcommunity.net/private/";
    
    // Set the fetcher for rdflib
    window.solidFetcher = solidClientAuthentication.fetch;
    
    async function main() {
        const kb = $rdf.graph();
        const fetcher = $rdf.fetcher(kb);
        try {
          await fetcher.load(privateResource);
          alert("Private resource successfully loaded");
        } catch(e) { alert(e); }
    }

    // Handle login and redirect logic
    document.getElementById('login').onclick = () => {
        solidClientAuthentication.login({
            oidcIssuer: idp,
            redirectUrl: window.location.href,
            clientName: "rdflib test"
        });
    };

    async function handleRedirectAfterLogin() {
        const session = await solidClientAuthentication.handleIncomingRedirect();
        if (session.info.isLoggedIn) main();
    }
    handleRedirectAfterLogin();
</script>