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DHI.Services.GeoServer for GIS — Internal Developer Guide (WFS → FeatureCollection)

Audience: devs using DHI.Services.GIS with GeoServer as a vector/feature source. For placeholders/auth/time/CRS details, see GeoServer Core.

What this provider does

  • Calls GeoServer WFS (or any endpoint returning GeoJSON) using your templated query.
  • Parses GeoJSON via NTS and converts to DHI.Spatial geometries.
  • Returns a FeatureCollection<string> (features + schema/attributes).
  • Sets feature CRS if the GeoJSON root has crs.properties.name.

Designed for WFS GetFeature. If pointed at WMS (images), it won’t work.

Capabilities & limitations

Operation Support Notes
Get(id) ✓ Main entry. Uses the templated URL.
Get(id, associations, outSpatialReference) ✓ Delegates to Get(id). Params currently ignored.
Get(id, filter, …) ✓ Delegates to Get(id). filter currently ignored.
GetAll() ✗ Not implemented.
GetEnvelope / GetFootprint ✗ Not implemented.
GetIds() ✓ Lists layer names via GeoServer REST /rest/layers.
Auth ✓ Optional Basic Auth; prefer HTTPS.
Geometry ✓ 3D/Measured types are flattened to 2D (see Core).
Client ✓ Instance HttpClient (you may inject); no global header sharing.

Building the HTTP request (query template)

Typical WFS (GeoJSON) template:

[group]/ows?service=WFS&version=1.1.0&request=GetFeature
&typeName=[group]:[layer]
&srsName=[crs]
&bbox=[boundingbox]
&outputFormat=application/json

If the ID carries Time, the provider appends &time=yyyy-MM-ddThh:mm:ss.fffZ (12-hour, see Core).

If your template includes [width]/[height], your ID must include Size=....

ID grammar (what you pass as {id})

Parsed by GeoServerFeatureCollectionId (semicolon-separated key=value):

  • Group=<workspace> (string)
  • Layer=<layerName> (string)
  • Crs=<EPSG:XXXX> (string) — default EPSG:3857
  • BoundingBox=<xmin,ymin,xmax,ymax> (double; culture-invariant .)
  • Size=<width,height> (ints; only if your template uses [width]/[height])
  • Time=<timestamp> ParseExact with formats: "s", "u", or "O" (e.g., 2021-09-20T00:00:00Z)

Examples

Group=demo;Layer=roads;Crs=EPSG:4326;BoundingBox=12,55,13,56
Group=hydro;Layer=gauges;Crs=EPSG:3857;BoundingBox=1320000,7400000,1340000,7420000;Time=2021-09-20T00:00:00Z
Group=land;Layer=buildings;Size=1024,768;Crs=EPSG:3857;BoundingBox=12.0,55.0,13.0,56.0

Behavior: unknown keys are ignored (only documented keys affect substitution).

Wiring

A) Connections (Web API hosts)

"geoserver": {
  "$type": "DHI.Services.GIS.WebApi.GisServiceConnection, DHI.Services.GIS.WebApi",
  "ConnectionString": "BaseUrl=http://localhost:8080/geoserver/;Query=[group]/ows?service=WFS&version=1.1.0&request=GetFeature&typeName=[group]:[layer]&srsName=[crs]&bbox=[boundingbox]&outputFormat=application/json;UserName=user;Password=pass",
  "RepositoryType": "DHI.Services.Provider.GeoServer.FeatureCollectionRepository, DHI.Services.Provider.GeoServer",
  "Name": "GeoServer WFS",
  "Id": "geoserver"
}

B) Programmatic

var query =
  "[group]/ows?service=WFS&version=1.1.0&request=GetFeature" +
  "&typeName=[group]:[layer]" +
  "&srsName=[crs]" +
  "&bbox=[boundingbox]" +
  "&outputFormat=application/json";

ServiceLocator.Register(
  new GisService(
    new DHI.Services.Provider.GeoServer.FeatureCollectionRepository(
      baseUrl: "https://my.geoserver.company/geoserver/",
      query: query,
      userName: "user",
      password: "pass")),
  "geoserver");

Examples

Fetch features for a viewport (EPSG:4326)

string id =
  "Size=800,400;" +
  "Crs=EPSG:4326;" +
  $"BoundingBox={xmin},{ymin},{xmax},{ymax};" +
  "Layer=states;Group=topp";

var repo = new FeatureCollectionRepository(
  "BaseUrl=http://localhost/geoserver/;" +
  "Query=wfs?service=WFS&version=1.0.0&request=GetFeature&typeName=[group]:[layer]&outputFormat=application/json&srsName=[crs]&bbox=[boundingbox];" +
  "UserName=admin;Password=geoserver");

var maybe = repo.Get(id);
return maybe.HasValue ? Ok(maybe.Value) : NotFound();

List layer ids via REST

var repo = Services.Get<GisService<string>>("geoserver").Repository;
foreach (var name in repo.GetIds()) Console.WriteLine(name);

Performance tips

  • Always pass a tight BoundingBox for server-side clipping.
  • Use GeoServer layer/view config (or extend your template with CQL) to reduce attributes/feature counts.
  • Consider pagination (maxFeatures/count) in templates for large responses.

Troubleshooting

  • HTTP 200 but empty → confirm endpoint is WFS with outputFormat=application/json.
  • CRS missing → your server emitted RFC-7946 GeoJSON (no crs); interpret in requested Crs.
  • Layer 404 → verify Group/Layer spelling and credentials.
  • Time weirdness → provider sends hh (12-hour). If you need HH, use your own [time] placeholder or adjust code.

Design notes (under the hood)

  • FeatureCollectionRepository builds the query by replacing placeholders; if Time is set, appends &time=… (see Core).
  • Before NTS parsing: json.Replace("MULTILINESTRING Z","MULTILINESTRING").
  • After conversion: if GeoJSON root has crs.properties.name, assign to each feature Geometry.CRS.
  • GetIds() hits /rest/layers and extracts name.