4. OpenSocial JavaScript API is good
<script type="text/javascript">
function init() {
var req = opensocial.newDataRequest();
req.add(req.newFetchPersonRequest(
opensocial.IdSpec.PersonId.VIEWER), "viewer");
req.send(function(data) {
var viewer = data.get("viewer").getData();
var id = viewer.getId();
var name = viewer.getDisplayName();
var thumbnailUrl = viewer.getField(
opensocial.Person.Field.THUMBNAIL_URL);
});
}
gadgets.util.registerOnLoadHandler(init); 4
</script>