> ## Documentation Index
> Fetch the complete documentation index at: https://dms.dzaleka.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Linked Data Export
> Export DMS records as JSON-LD to publish heritage metadata on the semantic web and integrate with library catalogues and linked open data portals.
JSON-LD (JSON for Linked Data) is a W3C standard that adds semantic meaning to JSON by associating each field with a globally recognised vocabulary term. Exporting your DMS records as JSON-LD makes them machine-readable by search engines, library catalogue systems, and linked open data portals — without changing how they look to a human reader.
## Why it matters
A plain DMS JSON record uses field names like `creator` and `title`. A JSON-LD export maps those same fields to precise URIs from established vocabularies:
* `creator` → `http://purl.org/dc/elements/1.1/creator`
* `title` → `http://purl.org/dc/elements/1.1/title`
* `name` (on a creator) → `http://xmlns.com/foaf/0.1/name`
This means any application that understands those vocabularies can consume your metadata without custom parsing.
## Exporting a single record
```bash theme={null}
dms export records/story_b3e7c8a1.json
```
By default the output file is placed next to the input with a `.jsonld` extension:
```
records/story_b3e7c8a1.jsonld
```
Use `--output` to choose a different path:
```bash theme={null}
dms export records/story_b3e7c8a1.json --output exports/story.jsonld
```
## Exporting an entire collection
Pass `--dir` to export every `.json` file in a directory as a single JSON-LD `@graph` document:
```bash theme={null}
dms export --dir records/
```
This writes a `collection.jsonld` file into the directory. Each record becomes a node in the `@graph` array, sharing a single top-level `@context` block:
```bash theme={null}
dms export --dir records/ --output exports/all-records.jsonld
```
## Vocabulary mappings
DMS maps its fields to six linked data vocabularies defined in `schema/dms.jsonld`:
The core bibliographic vocabulary. Used for the fundamental descriptive fields:
| DMS field | Mapped to |
| ----------------- | ---------------------- |
| `id` | `dc:identifier` |
| `title` | `dc:title` |
| `description` | `dc:description` |
| `type` | `dc:type` |
| `language` | `dc:language` |
| `format` | `dc:format` |
| `subject` | `dc:subject` |
| `rights` | `dc:rights` |
| `source` | `dc:source` |
| `date.created` | `dcterms:created` |
| `date.event_date` | `dcterms:date` |
| `rights.license` | `dcterms:license` |
| `rights.holder` | `dcterms:rightsHolder` |
| `location` | `dcterms:spatial` |
Used to describe people involved in creating or contributing to a record:
| DMS field | Mapped to |
| ----------------- | -------------------- |
| `creator[].name` | `foaf:name` |
| each creator node | `@type: foaf:Person` |
Role mappings to FOAF include `author` → `foaf:maker`.
Provides document-type classifications and roles specific to bibliographic resources:
| DMS type | BIBO mapping |
| --------------------------- | -------------------------- |
| `story`, `document`, `poem` | `bibo:Document` |
| `audio` | `bibo:AudioDocument` |
| `video` | `bibo:AudioVisualDocument` |
| `event` | `bibo:Event` |
Creator roles include `interviewer` → `bibo:interviewer`, `editor` → `bibo:editor`, `translator` → `bibo:translator`.
| DMS field | Mapped to |
| ------------------- | ----------------- |
| `source.collection` | `bibo:Collection` |
Provides rich type mappings recognised by Google, Bing, and major catalogues:
| DMS type | Schema.org @type |
| ---------- | ------------------------ |
| `story` | `schema:Article` |
| `photo` | `schema:Photograph` |
| `document` | `schema:DigitalDocument` |
| `audio` | `schema:AudioObject` |
| `video` | `schema:VideoObject` |
| `event` | `schema:Event` |
| `map` | `schema:Map` |
| `artwork` | `schema:VisualArtwork` |
| `site` | `schema:Place` |
| `poem` | `schema:CreativeWork` |
Additional field mappings: `creator[].affiliation` → `schema:affiliation`, `coverage.start_date` → `schema:startDate`, `coverage.end_date` → `schema:endDate`.
Used for geographic coordinates on the `location` object:
| DMS field | Mapped to |
| -------------------- | ---------- |
| `location.latitude` | `geo:lat` |
| `location.longitude` | `geo:long` |
The SKOS namespace is included in the context for future use in classifying subject tags as concept scheme entries, enabling interoperability with controlled vocabulary systems and thesauri.
## Example JSON-LD output
The following shows what the `examples/story.json` record looks like after export. The `@context` block is sourced directly from `schema/dms.jsonld`:
```json story_b3e7c8a1.jsonld theme={null}
{
"@context": {
"dms": "https://github.com/Dzaleka-Connect/Dzaleka-Metadata-Standard/schema#",
"dc": "http://purl.org/dc/elements/1.1/",
"dcterms": "http://purl.org/dc/terms/",
"schema": "https://schema.org/",
"foaf": "http://xmlns.com/foaf/0.1/",
"bibo": "http://purl.org/ontology/bibo/",
"xsd": "http://www.w3.org/2001/XMLSchema#",
"geo": "http://www.w3.org/2003/01/geo/wgs84_pos#",
"skos": "http://www.w3.org/2004/02/skos/core#"
},
"@type": ["dms:HeritageRecord", "schema:Article"],
"@id": "urn:dms:b3e7c8a1-4d5f-6e7a-8b9c-0d1e2f3a4b5c",
"dc:identifier": "b3e7c8a1-4d5f-6e7a-8b9c-0d1e2f3a4b5c",
"title": "Journey to Dzaleka: A Story of Hope",
"type": "story",
"description": "An oral history account of a Congolese family's journey from Bukavu to Dzaleka Refugee Camp in 2015.",
"language": "en",
"creator": [
{
"@type": "foaf:Person",
"name": "Marie Consolée",
"role": "narrator"
},
{
"@type": "foaf:Person",
"name": "Jean-Baptiste Mushimiyimana",
"role": "interviewer",
"affiliation": "Dzaleka Digital Heritage Project"
}
],
"date": {
"created": "2024-03-15",
"event_date": "2015-08-22"
},
"subject": ["oral history", "displacement", "Congo", "journey", "resilience", "community", "arrival"],
"location": {
"@type": "schema:Place",
"name": "Dzaleka Refugee Camp",
"area": "Community Center",
"latitude": -13.7833,
"longitude": 33.9833
},
"format": "text/plain",
"rights": {
"license": "CC-BY-NC-4.0",
"access_level": "public",
"holder": "Marie Consolée"
},
"schema_version": "1.0.0"
}
```
Key differences from the plain JSON record:
* `@context` declares all vocabulary prefix bindings
* `@type` is set to both `dms:HeritageRecord` and the appropriate Schema.org type (`schema:Article` for a story)
* `@id` is a `urn:dms:` URI derived from the record's UUID
* `id` is preserved as `dc:identifier`
* Each creator gets `"@type": "foaf:Person"`
* The `location` object gets `"@type": "schema:Place"`
## Use cases
Dublin Core and BIBO mappings make DMS records directly importable into library management systems such as DSpace, Omeka, and Koha.
Publish a `collection.jsonld` graph document to a SPARQL endpoint or a static open data portal for query by the wider research community.
Schema.org `@type` values allow Google Knowledge Graph and Bing to index heritage records as structured data, improving discoverability.
Shared vocabulary URIs mean DMS records can be joined with datasets from other institutions that use Dublin Core or FOAF without custom data-mapping work.