OpenLayers are not rendering MapServer layer

Question

I have a MapServer layer, Roads in this instance, and I've set its STATUS to ON. I want to render this as a WMS service using OpenLayers. So I've set all the Metadata Section in the LAYER section in the MAP file. Then in OpenLayers I have the following snippet:

 var params = {
              LAYERS: 'Roads',
              FORMAT: 'image/png',
              VERSION: '1.1.1',
       }

       var source = new ol.source.ImageWMS({
            url: 'http://localhost/cgi-bin/mapserv?map=/home/user/mapdata/fifth.map&layer=Roads',
          params: params
       });

       var layer = new ol.layer.Image({
            source: source     
       });

       var center = ol.proj.transform([21.768006, 39.556202], 'EPSG:4326', 'EPSG:3857');

       var view = new ol.View({
              center: center,
              zoom: 15
       });


       var map = new ol.Map({
            target: 'map',
            view: view,
            renderer: 'dom'
       });

       map.addLayer(layer);

However, the layer is never rendered, although in the url I pass the layer=Roads parameter. If I set the STATUS to default in the map file everything works well but in this occasion, not. Any idea?

Answer 1

The parameters should be: var params = { 'LAYERS': 'Roads', 'FORMAT': 'image/png', 'VERSION': '1.1.1', }

Answer 2

Put all the projection you need in the web section of your mapfile

WEB
    METADATA
        'wms_enable_request'  '*'
        # Allow WMS service to serve multiple projections
        # Only EPSG, AUTO2, CRS codes are supported as part of WMS 1.3.0
        'wms_srs' 'EPSG:4326 EPSG:3857 EPSG:54009'
    END
END

Source from Mapserver doc