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Tiled WMS

wms11 tile9 tilelayer3

Example of a tiled WMS layer.

WMS can be used as a Tile layer, as shown here, or as an Image layer, as shown in the Single Image WMS example example. Tiles can be cached, so the browser will not re-fetch data for areas that were viewed already. But there may be problems with repeated labels for WMS servers that are not aware of tiles, in which case single image WMS will produce better cartography.

main.js
import 'ol/ol.css';
import Map from 'ol/Map';
import OSM from 'ol/source/OSM';
import TileLayer from 'ol/layer/Tile';
import TileWMS from 'ol/source/TileWMS';
import View from 'ol/View';

const layers = [
  new TileLayer({
    source: new OSM(),
  }),
  new TileLayer({
    extent: [-13884991, 2870341, -7455066, 6338219],
    source: new TileWMS({
      url: 'https://ahocevar.com/geoserver/wms',
      params: {'LAYERS': 'topp:states', 'TILED': true},
      serverType: 'geoserver',
      // Countries have transparency, so do not fade tiles:
      transition: 0,
    }),
  }),
];
const map = new Map({
  layers: layers,
  target: 'map',
  view: new View({
    center: [-10997148, 4569099],
    zoom: 4,
  }),
});
index.html
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Tiled WMS</title>
    <!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
    <script src="https://unpkg.com/elm-pep"></script>
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="https://cdn.polyfill.io/v3/polyfill.min.js?features=fetch,requestAnimationFrame,Element.prototype.classList,URL,TextDecoder,Number.isInteger"></script>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <script src="main.js"></script>
  </body>
</html>
package.json
{
  "name": "wms-tiled",
  "dependencies": {
    "ol": "6.9.0"
  },
  "devDependencies": {
    "parcel": "^2.0.0-beta.1"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --public-url . index.html"
  }
}