LODE 2.0

Semantic artefact URL*

URL File

Resource URI (optional)

Select a format*

Language code (optional)

Show warnings

LODE 2.0 is an open source service that automatically extracts entities from semantic artefacts (OWL, RDF/RDFS, SKOS) and renders them, together with their textual definitions, as a human-readable HTML page designed for browsing and navigation through embedded links. Depending on the parameters specified, the generated page takes into account both ontological axioms and annotations; its stylesheets are based on the W3C CSSs for Recommendation documents. LODE 2.0 is the successor of LODE.

Endpoints

/extract — returns the HTML documentation page, or an RDF serialization when format is set.
/build — returns a ZIP with the complete static site: one HTML page per resource, Turtle/RDF-XML/N3 serializations and stylesheets, ready for any web server or GitHub Pages.

Note

/build is intended for interactive, one-off use. For automated workflows (CI/CD, GitHub Actions) install LODE locally and use the lode build command instead.

Implementation status

Only read_as=owl is currently enabled. RDF/RDFS (read_as=rdf) and SKOS (read_as=skos) are under development; requesting them returns an error.

Parameters

Parameter	Type	Required	Endpoint	Description	Example
`url`	string	Yes, mutually exclusive with `file`	`/extract`, `/build`	Full URL of the semantic artefact to process. Both semantic artefact URIs and direct links to RDF files (e.g. `.ttl`, `.rdf`, `.owl`) are accepted. Mutually exclusive with `file`.	`url=http://purl.org/spar/fabio.ttl`
`file`	file	Yes, mutually exclusive with `url`	`/extract`, `/build`	The semantic artefact file to upload and process. Accepted formats: `.rdf`, `.owl`, `.ttl`, `.n3`, `.nt`, `.xml`. Mutually exclusive with `url`.	`file={LOCAL_PATH}`
`read_as`	enum	No	`/extract`, `/build`	How to interpret the RDF graph. One of `owl`, `rdf`, `skos`. Only `owl` is currently enabled. Defaults to `owl`.	`read_as=owl`
`resource`	string (URI)	No	`/extract` only	URI of a specific resource to render. If omitted, the full artefact is documented.	`resource=http://purl.org/spar/fabio/ArchivalDocument`
`format`	enum	No	`/extract` only	Returns the RDF serialization instead of the HTML page. One of `ttl` (Turtle), `rdf` (RDF/XML), `n3` (N3). When combined with `resource`, only the axioms of that resource are serialized. If omitted, the `Accept` header is honoured (`text/turtle`, `application/rdf+xml`, `text/n3`); otherwise HTML is returned.	`format=ttl`
`lang`	string	No	`/extract`, `/build`	Preferred language code for annotations (e.g. `en`, `it`, `fr`). Defaults to `en`.	`lang=en`
`warnings`	boolean	No	`/extract`, `/build`	When set to `true`, the documentation page also lists structural warnings raised during parsing (e.g. malformed restrictions, OWL 2 DL violations). Defaults to `false`.	`warnings=true`
`imported`	boolean	No	`/extract`, `/build`	OWL only. When set to `true`, the axioms contained in the ontologies directly imported by the target artefact are included. If both `imported` and `closure` are specified, only `imported` is used.	`imported=true`
`closure`	boolean	No	`/extract`, `/build`	OWL only. When set to `true`, the transitive closure of all imported ontologies is included. If both `imported` and `closure` are specified, only `imported` is used.	`closure=true`
`cache`	boolean	No	`/extract`, `/build`	URL source only. When `true` (default), the processed URL is served from a 4-hour server-side cache when available. Set to `false` to discard the cached copy and re-fetch the URL; the fresh result then replaces the cache.	`cache=false`

Examples

Live documentation

    https://lode.opencitations.net/extract?url=http://purl.org/spar/fabio.ttl&read_as=owl
    https://lode.opencitations.net/extract?url=http://purl.org/spar/fabio&read_as=owl
    https://lode.opencitations.net/extract?url=http://www.w3.org/2004/09/fresnel&read_as=owl&warnings=true
    https://lode.opencitations.net/extract?url=http://purl.org/spar/fabio&read_as=owl&imported=true&lang=en
    https://lode.opencitations.net/extract?url=http://purl.org/spar/fabio&read_as=owl&closure=true
    https://lode.opencitations.net/extract?url=http://purl.org/spar/fabio&read_as=owl&resource=http://purl.org/spar/fabio/Abstract&lang=it
    https://lode.opencitations.net/extract?url=http://purl.org/spar/fabio&read_as=owl&cache=false

RDF content negotiation (`format`)

    https://lode.opencitations.net/extract?url=http://purl.org/spar/fabio&read_as=owl&format=ttl
    https://lode.opencitations.net/extract?url=http://purl.org/spar/fabio&read_as=owl&format=rdf
    https://lode.opencitations.net/extract?url=http://purl.org/spar/fabio&read_as=owl&format=n3&resource=http://purl.org/spar/fabio/Abstract

Static documentation (ZIP)

    https://lode.opencitations.net/build?url=http://purl.org/spar/fabio&read_as=owl
    https://lode.opencitations.net/build?url=http://purl.org/spar/fabio&read_as=owl&lang=en
    https://lode.opencitations.net/build?url=http://purl.org/spar/fabio&read_as=owl&imported=true
    https://lode.opencitations.net/build?url=http://purl.org/spar/fabio&read_as=owl&closure=true&warnings=true

Content negotiation

LODE can be combined with content negotiation to serve this human-readable version to browsers and the raw artefact to ontology editors such as Protégé, following the Best Practice Recipes for Publishing RDF Vocabularies. An exemplar implementation of such content negotiation is given in the Best Practice Recipes for Publishing RDF Vocabularies by using the .htaccess file:

Example .htaccess

    AddType application/rdf+xml .rdf

    # Rewrite engine setup
    RewriteEngine On

    # Rewrite rule to serve HTML content
    RewriteCond %{HTTP_ACCEPT} !application/rdf\+xml.*(text/html|application/xhtml\+xml)
    RewriteCond %{HTTP_ACCEPT} text/html [OR]
    RewriteCond %{HTTP_ACCEPT} application/xhtml\+xml [OR]
    RewriteCond %{HTTP_USER_AGENT} ^Mozilla/.*
    RewriteRule ^ontology\$ https://w3id.org/lode/http://www.mydomain.com/ontology [R=303,L]

    # Rewrite rule to serve RDF/XML content if requested
    RewriteCond %{HTTP_ACCEPT} application/rdf\+xml
    RewriteRule ^ontology\$ ontology.owl [R=303]

    # Choose the default response
    RewriteRule ^ontology\$ ontology.owl [R=303]

Reporting bugs

LODE 2.0 is developed in the open. Open an issue at github.com/opencitations/lode/issues.