}
public int addPersistentSearch(SearchOp op) throws IOException {
LdapMessage request = new LdapMessage(
LdapASN1Constant.OP_SEARCH_REQUEST, op.getRequest(),
new Control[] { new PersistentSearchControl() });
Integer messageID = Integer.valueOf(request.getMessageId());
// set lock to null, indicate this is persistent search
requests.put(messageID, new Element(null, new LdapMessage(op