private void writeHeader() throws IOException { out.write(Server.HEADER.array()); out.write(Server.CURRENT_VERSION); DataOutputBuffer buf = new DataOutputBuffer(); ObjectWritable.writeObject(buf, remoteId.getTicket(), UserGroupInformation.class, conf); int bufLen = buf.getLength(); out.writeInt(bufLen); out.write(buf.getData(), 0, bufLen); }