Le portail francophone de la géomatique

// create a group layer (with several layers in the "layers" param)
            // to show how the LayerParamLoader works
            new OpenLayers.Layer.WMS("Tasmania (Group Layer)",
                "http://demo.opengeo.org/geoserver/wms", {
                    layers: [
                        "topp:tasmania_state_boundaries",
                        "topp:tasmania_water_bodies",
                        "topp:tasmania_cities",
                        "topp:tasmania_roads"
                    ],
                    transparent: true,
                    format: "image/gif"
                }, {
                    isBaseLayer: false,
                    buffer: 0,
                    // exclude this layer from layer container nodes
                    displayInLayerSwitcher: false,
                    visibility: false
                }
            )

{
        nodeType: "gx_layer",
        layer: "Tasmania (Group Layer)",
        isLeaf: false,
        // create subnodes for the layers in the LAYERS param. If we assign
        // a loader to a LayerNode and do not provide a loader class, a
        // LayerParamLoader will be assumed.
        loader: {
            param: "LAYERS"
        }
    }