function doMap()
{
    var map = new GMap2(document.getElementById("map"));
    map.addControl(new GLargeMapControl());
    map.addControl(new GMapTypeControl());
    map.setCenter(new GLatLng(0, 0), 1);

    GDownloadUrl("geo.php", function(data, responseCode) 
      {            
         var xml = GXml.parse(data);
         var photos = xml.documentElement.getElementsByTagName("photo");
         
         var s = "";
         var n = Math.min(photos.length, 5);
         for (var i = 0; i < n; i++) 
         {
            s += photos[i].getAttribute("id") + ", ";
         }
         
         alert("Ids received:\n\n" + s);
      });
}