100. Live Layers (OGC API - Features)¶

Technical notes on the live layers that BIMS publishes for GIS clients. For how to publish a layer, see the administrator guide.

100.1 Endpoints¶

A layer published from the BIMS filter (see the user guide) follows OGC API - Features Part 1 (Core), with GeoJSON output. All paths are below /ogc/layers/<token>/:

Path	Returns
`/`	Landing page with links to the other documents
`/api`	OpenAPI definition
`/conformance`	Conformance classes (core, oas30, geojson)
`/collections`	The list of collections (one, with id `records`) and its spatial extent
`/collections/records`	The `records` collection
`/collections/records/items?limit=1000&offset=0`	The features, as `application/geo+json`
`/collections/records/items/<uuid>`	A single record

The items endpoint accepts limit (default 1000, maximum 5000), offset, and bbox. The response contains numberMatched, numberReturned and next/prev links. Example, abbreviated:

{
  "type": "FeatureCollection",
  "numberMatched": 978,
  "numberReturned": 1,
  "links": [
    {"rel": "self", "href": ".../collections/records/items?limit=1&offset=0"},
    {"rel": "next", "href": ".../collections/records/items?limit=1&offset=1"}
  ],
  "features": [
    {
      "type": "Feature",
      "id": "b73a9163-12a7-4849-85fa-9a9aea60344a",
      "geometry": {"type": "Point", "coordinates": [22.916667, -32.25]},
      "properties": {"Site code": "L1BREI-00001", "Sampling date": "1978-02-15", "Kingdom": "Plantae"}
    }
  ]
}

The management API used by the dialog is /api/ogc-layers/ (list, create, preview/, rename, rotate-token/, delete). It requires a logged-in user.

100.2 Limits and protection of the server¶

Live layers read from the shared BIMS database, so they are limited on purpose. The defaults below can be changed by the system administrator with environment variables (see core/settings/ogc.py).

Setting	Default	Meaning
`OGC_LAYERS_ENABLED`	on	Switches every layer URL off when set to false (answers 503)
`OGC_LAYER_MAX_RECORDS`	100000	Largest layer allowed
`OGC_LAYER_DEFAULT_PAGE_SIZE` / `OGC_LAYER_MAX_PAGE_SIZE`	1000 / 5000	Records per page
`OGC_MAX_LAYERS_PER_OWNER`	20	Active layers one user may have
`OGC_LAYER_STATEMENT_TIMEOUT`	20 s	A layer query is cancelled after this time
`OGC_LAYER_MAX_CONCURRENT_EVALUATIONS`	4	Layers evaluated at the same time, per tenant
`OGC_RATE_LIMIT_IP` / `_LAYER` / `_OWNER`	600 / 1200 / 2400 per minute	Rate limits. A client over the limit receives 429 with `Retry-After`
`OGC_LAYER_MAX_FAILURES`	5	A layer is switched off after this many timeouts in a row
`OGC_HTTP_CACHE_MAX_AGE`	60 s	How long a client may reuse a response

A busy server answers 503 with Retry-After; clients normally retry on their own. A revoked, deleted or unknown token answers 404.