Communications

The ZY provides 2 TCP Server ports (5240 and 5241) to interface with other programs, such as the ZIY. The class TCPSocket is used to set up these TCP servers. TCPSocket uses the FTP Software PC/TCP SDK libraries to communicate with the PC/TCP kernel. When a program is connected to one of the server sockets, another program can connect to the second server socket and ``eavesdrop'' on the communications. This second program can also issue commands to the ZY. This second socket is very useful for troubleshooting, and also to issue commands to the ZY that the ZIY cannot yet issue (due to the ZIY implementation). Because of the ZY's ASCII command interface (see section 2.10), a Telnet program can be used to connect to the ZY on one of the two ports, and used to issue commands to the ZY and to display the return from the ZY. For example, the following is a short telnet session to ZY11 using the SunOS `telnet' utility on the host bunda:

  (41) rcreager on bunda% telnet zy11 5240
  Trying 192.33.116.32...
  Connected to zy11.
  Escape character is '^]'.
  HELLO This is ZY11 ver. 2.20
  CONNECT 1, 5240
  rds config.sys
  0       50932.65071409  RDS 0, parameter 'config.sys' not a numeric value
  rdf config.sys
  0       50932.65082081  RDF 1, >stacks=8,512
  0       50932.65082088  RDF 1, >lastdrive=b
  0       50932.65082095  RDF 1, >
  0       50932.65082101  RDF 1, >files=40
  0       50932.65082106  RDF 1, >buffers=20
  0       50932.65082113  RDF 1, >
  0       50932.65082119  RDF 1, >rem Network packet drivers
  0       50932.65082126  RDF 1, >device=a:\NDIS\protman.dos /I:a:\NDIS
  0       50932.65082133  RDF 1, >device=a:\NDIS\dis_pkt.gup
  0       50932.65082142  RDF 1, >device=a:\NDIS\at1700.dos
  bye
  0       50932.65128786  BYE 1, 5240, Closing Connection
  Connection closed by foreign host.
  (42) rcreager on bunda%
 

As can be seen, the ZY prefaces all command returns with the TID (set to 0, as none was provided by the user at the `telnet' prompt) and the time stamp for the command return. The ability to directly connect to the ZY using a telnet program is very useful for troubleshooting. There also exists a test terminal program for the ZY, T.EXE. This NT console program serves the same purpose as the telnet program, but is programmed specifically for the ZY. For example, command line switches on T.EXE can turn off the echoing of the TID and time stamps. T.EXE is also used to test experimental features such as the tracking feature, without having to modify the full blown ZIY program before the feature has been stabilized. The `telnet' or T.EXE programs are also very useful when connected to the second TCP port. This is especially true when troubleshooting the ZIY, as all communications from the ZY to the ZIY will be echoed on the `telnet' or T.EXE terminals as well.