question: public void reply ( Z21Reply msg ) { if ( msg . isXPressNetTunnelMessage ( ) ) { XNetReply reply = msg . getXNetReply ( ) ; log . debug ( "Z21 Reply {} forwarded to XPressNet implementation as {}" , msg , reply ) ; for ( int i = 0 ; i < reply . getNumDataElements ( ) ; i ++ ) { try { outpipe . writeByte ( reply . getElement ( i ) ) ; } catch ( java . io . IOException ioe ) { log . error ( "Error writing XPressNet Reply to XPressNet input stream." ) ; } } } }
target:  Member function that will be invoked by a z21Interface implementation to forward a z21 message from the layout.