var map;
	var ajaxRequest;
	var plotlist;
	var plotlayers=[];

	function initmap(){
		// set up the AJAX stuff
		ajaxRequest=GetXmlHttpObject();
		if (ajaxRequest==null) {
			alert ("This browser does not support HTTP Request");
			return;
		}

		// set up the map
		map = new L.Map('map');

		var osmUrl='http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png';
		var osmAttrib='Map data &copy; <a href="http://openstreetmap.org">OpenStreetMap</a> contributors';
		var osm = new L.TileLayer(osmUrl, {minZoom: 8, maxZoom: 12, attribution: osmAttrib});		

		map.setView(new L.LatLng(51.3, 0.7),9);
		map.addLayer(osm);
		askForPlots();
		map.on('moveend', onMapMove);
	}

	function askForPlots() {
		// request the marker info with AJAX for the current bounds
		var bounds=map.getBounds();
		var minll=bounds.getSouthWest();
		var maxll=bounds.getNorthEast();
		var msg='leaflet/findbybbox.cgi?format=leaflet&bbox='+minll.lng+','+minll.lat+','+maxll.lng+','+maxll.lat;
		ajaxRequest.onreadystatechange = stateChanged; 
		ajaxRequest.open('GET', msg, true);
		ajaxRequest.send(null); 
	}

	function onMapMove(e) { askForPlots(); }

	function GetXmlHttpObject() {
		if (window.XMLHttpRequest) { return new XMLHttpRequest(); }
		if (window.ActiveXObject)  { return new ActiveXObject("Microsoft.XMLHTTP"); }
		return null;
	}

	function stateChanged() {
		// if AJAX returned a list of markers, add them to the map
		if (ajaxRequest.readyState==4) {
			//use the info here that was returned
			if (ajaxRequest.status==200) {
				plotlist=eval("(" + ajaxRequest.responseText + ")");
				removeMarkers();
				for (i=0;i<plotlist.length;i++) {
					var plotll = new L.LatLng(plotlist[i].lat,plotlist[i].lon, true);
					var plotmark = new L.Marker(plotll);
					plotmark.data=plotlist[i];
					map.addLayer(plotmark);
					plotmark.bindPopup("<h3>"+plotlist[i].name+"</h3>"+plotlist[i].details);
					plotlayers.push(plotmark);
				}
			}
		}
	}

	function removeMarkers() {
		for (i=0;i<plotlayers.length;i++) {
			map.removeLayer(plotlayers[i]);
		}
		plotlayers=[];
	}