if ( filename != null ) {
synchronized ( subscribers ) {
try {
FileOutputStream outputStream = new FileOutputStream(filename);
XMLOutputStreamWriter writer = new XMLOutputStreamWriter(outputStream);
writer.writeXMLDeclaration();
writer.writeStartTag(XMLWriter.createStartTag(E_SUBSCRIPTIONS));
for ( Iterator i = subscribers.iterator(); i.hasNext(); ) {
Subscriber subscriber = (Subscriber)i.next();
writer.writeStartTag(XMLWriter.createStartTag(E_SUBSCRIPTION, new String[][] {
{ A_ID, String.valueOf(subscriber.getId()) } }));