Tiled WMS

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.

<!DOCTYPE html>
<html>
  <head>
    <title>Tiled WMS</title>
    <link rel="stylesheet" href="https://openlayers.org/en/v5.1.2/css/ol.css" type="text/css">
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>

  </head>
  <body>
    <div id="map" class="map"></div>
    <script>
      import Map from 'ol/Map.js';
      import View from 'ol/View.js';
      import TileLayer from 'ol/layer/Tile.js';
      import OSM from 'ol/source/OSM.js';
      import TileWMS from 'ol/source/TileWMS.js';


      var 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
          })
        })
      ];
      var map = new Map({
        layers: layers,
        target: 'map',
        view: new View({
          center: [-10997148, 4569099],
          zoom: 4
        })
      });
    </script>
  </body>
</html>