Msj. #33701  Tipo:B  Stat:$  Para:YAPP    @WW       Exp.:FC1MSL
Fecha  : 09-Oct-92 00:42
Titulo : Yapp protocol.
Path: !EA7GFG!EA7DSS!EA7CNM!EB7BUH!EA5URD!EA5GKR!EB5HLN!EA5VDR!EA5BU!EA6CE!
      !EA6URP!EA3RDG!EA3ET!F2XC!F6KDJ!TK0KP!FF6KIF!ON1KEZ!ON1KGX!ON7RC!LX0PAC!
      !DB0GE!HB9EAS!HB9OS!HB9AJ!HB9PD!HB9PD!HB9IAP!
From: FC1MSL@HB9IAP.SROM.CHE.EU
To  : YAPP@WW

*** REDIF ***


YAPP(tm) protocol for Packet Radio binary file transfer
(c) 1986, Jeff Jacobsen - WA7MBL
Revision 1.1   06/23/86

----------------------------------------------------------

YAPP PACKET TYPES

Size of packet data ranges from 2-258 bytes.
len = length of following bytes (not including len)

RR Rcv_Rdy      ACK  01
RF Rcv_File     ACK  02
AF Ack_EOF      ACK  03   [1.1]
AT Ack_EOT      ACK  04   [1.1]
SI Send_Init    ENQ  01
HD Send_Hdr     SOH  len  (Filename)  NUL  (File Size in ASCII)  NUL  (Opt)
DT Send_Data    STX  len  (Data)    {if len=0 then data length = 256}
EF Send_EOF     ETX  01
ET Send_EOT     EOT  01
NR Not_Rdy      NAK  len  (Optional Reason in ASCII)
CN Cancel       CAN  len  (Optional Reason in ASCII)
CA Can_Ack      ACK  05

{Following are for use in Server mode}
RI Rcv_Init     ENQ   02   len   (Filespec requested - wildcard allowed)
TX Text         DLE   len  (ASCII text for display)  {to send text from server}

{Unimplement - Reserved for Server Commands}
UU Comands      ENQ   03
                ENQ   04
                ENQ   05
                ...
                ENQ   FF

STATE TABLES for SEND

State         Send Pkt        Upon                  Next State
S (Send)      SI              RR                    SH
                              RF                    SD
                              NR                    Start/Done
                              First few timeouts    S
                              RI                    S
                              Other/Timeout         Abort

SH (Hdr)      HD              RF                    SD
                              NR                    Start/Done
                              Other/Timeout         Abort

SD (Data)     DT              (Not EOF)             SD
                              (EOF)                 SE

SE (EOF)      EF              AF (More files)       SH
                              AF (No More Files)    ST
                              Other/Timeout         Abort

ST (EOT)      ET              AT                    Start/Done
                              Other/Timeout         Start/Done



STATE TABLES for RECEIVE

State      On    If           Do          Send Pkt       Next State

R (Rec)    SI (ready)                       RR              RH
           SI (opt)*       open file        RF              RD
           SI (not ready)                   NR              Start/Done
           NR                                               Start/Done
           Other/Timeout                                    Abort

(opt)*  If header info not desired it is ok to
        open file and indicate ready for file

RH (Hdr)   HD              open file        RF              RD
           HD (no room)                     NR              Start/Done
           SI                                               RH
           ET                               AT              Start/Done
           Other/Timeout                                    Abort

RD (Data)  DT              store data                       RD
           EF              close file       AF              RH
           Other/Timeout                                    Abort

OTHER STATE

Any State          On CN         Send CA                   Start/Done
except CW

CW (Can_Wait)      On CA                                   Start/Done
                   On CN         Send CA                   CW
                   Timeout       Display Err Msg           Start/Done

Abort                            Send CN                   CW



--------
Starting States

For 2 users not using Remote Server

    Sender goes to State S, Receiver to State R after manually
    exchanging file names.  Since File Name is known, Receiver
    may optionally send RF from state R and bypass file header.
    Sender should give Receiver ample time to get into Receive
    State.


For Remote Server Mode

  USER (Start)                                       Next State
  User wishing to Send                               S
  User wishing to Receive          Send RI           R
  Other Server Request             Send COMMAND      Start

  SERVER (Start)

  Gets SI                                            R
  Gets RI             (file fnd)                     S
                      (no file)    Send NR           Start

  Gets COMMAND                    (Do Command)       Start


---------------------------------------------------------
All states except Send Data should timeout if nothing is heard
for a period of time Tc (Crash timer).  Send Data isn't expecting
any input and if it should receive some it must be a Cancel, or
a TX (text) packet, otherwise Abort.


--------
Revision 1.1 - Added AF & AT to acknowledge End of File and
End of Transfer.  This allows an automated sender to know that
a file was received successfully.  It also helps get past a
problem in the TNC-2 code by requiring the sender to wait for the
Ack-EOT before switching from transparent mode back to converse
mode.



==================

Extract from HAPN card software package.
73's de Eric, FC1MSL @ HB9IAP.#SROM.CHE.EU .
[Fin Msj. #33701 de FC1MSL]