question: static void writeReqFrame ( ByteBuffer bb , int methodId , long seq , int length ) throws IOException { int oldPos = bb . position ( ) ; boolean success = false ; try { bb . order ( ByteOrder . LITTLE_ENDIAN ) ; bb . putInt ( HRPC_MAGIC ) ; bb . putInt ( methodId ) ; bb . putLong ( seq ) ; bb . putInt ( length ) ; success = true ; } finally { if ( ! success ) { bb . position ( oldPos ) ; } } }
target:  Write the fixed-length request frame which starts packed RPC messages.