void onUpdateProgress(String progressId, String zoneId, int taskId) {
addCallback(progressId, zoneId, taskId);
}
void addCallback(final String progressId, final String zoneId, final int taskId) {
ajaxRenderer.addCallback(new JavaScriptCallback() {
public void run(JavaScriptSupport jss) {
float progress = taskManager.getProgress(taskId);
Link link = resources.createEventLink("updateProgress", progressId, zoneId, taskId);
JSONObject args = new JSONObject();
args.put("url", link.toString());