raster - Is QGIS Server working like this?

On CentOS 7 I have QGIS Server and QGIS Desktop installed. In QGIS Desktop I created a project with raster and vector data and saved it in a ".qgs" file. Then I copied the file in "/var/www/html/cgi-bin/" and also copied the files "qgis_mapserv.fcgi" and "wms_metadata.xml" into this directory.

In my html-file I created a raster layer:

        var layer = new ol.layer.Image({
            source: new ol.source.ImageWMS(({
            url: 'http://localhost/cgi-bin/qgis_mapserv.fcgi',
            params: {'LAYERS': 'RasterLayerName'},
            serverType: 'qgis',
            crossOrigin: null
            }))
        });

That worked once. In an other project it didn't work. And I couldn't add a vector layer.

Is this the way to refer to QGIS layers with OpenLayers?

Answer

It really works with a reference to qgis_mapserv.fcgi:

    var layer = new ol.layer.Tile({
    type: 'base',
    visible: true,
    source: new ol.source.TileWMS({
        url: 'http://localhost/cgi-bin/qgis_mapserv.fcgi',
        params: {'LAYERS': 'RasterLayerName', 'TILED': true},
    })

});

Then add the layer to your map.