var fromProjection = new OpenLayers.Projection("EPSG:4326");
        var toProjection = new OpenLayers.Projection("EPSG:3857");

        var map = new OpenLayers.Map("map");

        var vectorFormat = new OpenLayers.Format.GeoJSON();
        var vectorProtocol = new OpenLayers.Protocol.HTTP({
            url: "http://localhost:9000/getcoords",
            format: vectorFormat,
            params: {
                "city":"PARIS",
                "city_code":3
            }
        });
        var refresh = new OpenLayers.Strategy.Refresh({ force: true, active: true });
        var vectorStrategies = [new OpenLayers.Strategy.Fixed(), refresh];

        var osm = new OpenLayers.Layer.OSM();

        var vectors = new OpenLayers.Layer.Vector({
            protocol: vectorProtocol,
            strategies: vectorStrategies,
            format: vectorFormat
        });

        map.addLayers([osm, vectors]);
        map.setCenter(new OpenLayers.LonLat(2.3983034, 47.078038).transform(fromProjection, toProjection), 6);