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yappxfer.doc
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1990-10-14
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176 lines
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 indiate 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, Recevier
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.