Layers

Every table with a geometry column is a layer that can be rendered through WMS. The Layer API controls how a layer is drawn: its rendering properties, and its classes, which in turn contain styles and labels:

Layer (schema.table.geometry_column)
├── properties          Rendering and tile-cache settings
└── classes[]           Thematic groups of features
    ├── styles[]        How matching features are drawn
    └── labels[]        How matching features are labelled

A layer is identified by the key schema.table.geometry_column, e.g. rockhall.venues.the_geom. The configuration is translated to a MapServer mapfile on the server, so most properties map directly to MapServer parameters.

Get layers

Web App

HTTP

All layers

GET https://api.centia.io/api/v4/layers HTTP/1.1
Accept: application/json; charset=utf-8
Authorization: Bearer abc123

A specific layer

GET https://api.centia.io/api/v4/layers/rockhall.venues.the_geom HTTP/1.1
Accept: application/json; charset=utf-8
Authorization: Bearer abc123

Configure a layer

POST /api/v4/layers configures a layer declaratively in one atomic request: it sets the properties and replaces the entire classes array with the one you send. This is the recommended way to apply a complete styling in one go — for incremental changes, use the classes, styles and labels sub-resources instead.

Web App

HTTP

Configure a layer with one class, style and label

POST https://api.centia.io/api/v4/layers HTTP/1.1
Content-Type: application/json
Authorization: Bearer abc123

{
    "name": "rockhall.venues.the_geom",
    "properties": {
        "theme_column": "genre",
        "opacity": "80",
        "maxscaledenom": "500000"
    },
    "classes": [
        {
            "name": "Rock venues",
            "expression": "rock",
            "styles": [
                {
                    "symbol": "circle",
                    "color": "#FF0000",
                    "outlinecolor": "#FFFFFF",
                    "size": "10"
                }
            ],
            "labels": [
                {
                    "on": true,
                    "text": "[name]",
                    "size": "11",
                    "position": "auto"
                }
            ]
        }
    ]
}

Ids are preserved — if you send them back

Classes, styles and labels each carry a fixed, server-assigned id. POST /api/v4/layers accepts and round-trips these ids: include them in the payload to keep existing entries stable. Entries sent without an id are treated as new and get a fresh id.

Update layer properties

PATCH merges the keys you send into the layer's properties, leaving everything else — including classes — untouched:

Change opacity only

PATCH https://api.centia.io/api/v4/layers/rockhall.venues.the_geom HTTP/1.1
Content-Type: application/json
Authorization: Bearer abc123

{
    "properties": {
        "opacity": "50"
    }
}

Layer properties

All values are stored as strings — an empty string means unset — except where noted. The most commonly used properties:

Property	Description
theme_column	Column evaluated against each class's expression (MapServer CLASSITEM). Empty means classes match on logical expressions only.
geotype	Geometry type override: Default, POINT, LINE or POLYGON. Default derives it from the geometry column.
opacity	Layer opacity, 0–100.
minscaledenom / maxscaledenom	Scale range in which the layer is drawn (min = most zoomed-in bound, max = most zoomed-out bound).
symbolscaledenom	Scale at which symbols and text render at their true size; they scale as the map diverges from it.
label_column	Column exposed to label text/expressions (MapServer LABELITEM).
label_min_scale / label_max_scale	Scale range in which labels are drawn.
label_no_clip	Boolean. Avoids label jitter and duplicate labels across tiled requests.
polyline_no_clip	Boolean. Avoids discontinuities in dashed/symbolized lines across tiled requests.
cluster	Point-clustering distance in pixels. Empty disables clustering.
offsite	RGB pixel value MapServer should treat as background for raster layers.
bands	Raster band selection, comma-separated (1 band = greyscale, 3 = RGB, 4 = RGBA).
format	Tile image format: PNG (default), jpeg_low, jpeg_medium or jpeg_high.
cache	Tile cache backend: disk, sqlite, s3 or memcache.
ttl	Tile time-to-live in seconds (HTTP Expires/Cache-Control). Minimum 30.
auto_expire	Age in seconds after which a cached tile is refreshed on next access. Overrides ttl for that purpose.
meta_size	Metatile size (columns/rows per WMS request when building the tile cache). Default 3.
meta_buffer	Buffer in pixels around each metatile, cropped off to prevent edge artifacts.
layers	Comma-separated schema-qualified layer names rendered into the same cached tile.
lock	Boolean. Locks the tile cache so it cannot be cleared.

Delete a layer configuration

DELETE https://api.centia.io/api/v4/layers/rockhall.venues.the_geom HTTP/1.1
Authorization: Bearer abc123