The CZ package is a small set of FORTRAN callable routines used by FATMEN, PAW and other applications. It provides a simple means of starting a remote server and then exchanging character or binary data. The actual communication is performed by TCPAW, running over TCP/IP, or transparent DECnet task-to-task.
XZ is a small package built on top of CZ which permits remote I/O, such as OPEN, CLOSE, READ, WRITE etc. and remote file transfer.
TCPAW provides the network layer for many of the tools in the current CSPACK package is built. It consists of FORTRAN callable C routines, and is implemented on a variety of platforms, including VM/CMS, VAX/VMS, and Unix systems.
TCPAW uses the internet daemon (INETD) to start servers, except on VM/CMS, where REXEC is used.
SYSREQ is a facility developed at RAL for generalised inter-system communications. It allows commands to be sent to, and replies received from, services running in dedicated service machines under the VM/CMS. For example, all communication with the HEPVM Tape Management System (TMS), that was developed at the Rutherford Appleton Laboratory in the UK and is now running at several of the larger HEPVM sites, is via SYSREQ. At CERN, a facility has been developed to permit remote users use the facilities of SYSREQ, by forwarding the messages and replies over TCP/IP. This system is known as SYSREQ-TCP.
TELNETG is a modified version of the standard TELNET program that allows the input/output of a HIGZ based graphics session on a remote system to be displayed in a graphics window on the local workstation. TELNETG is available for Unix and VAX/VMS systems.
TAGIBM is a powerful 3270 terminal emulator similar to TELNETG but with full-screen emulation for IBM systems.
On all systems except VM/CMS and IBM MVS, the server for ZFTP, distributed PAW and the CZ/XZ FORTRAN routines is started using the internet daemon (INETD), except between VAX/VMS systems when the DECnet option is activated.
The inetd daemon is normally started when your system is rebooted. Once started, the inetd daemon listens for connections on certain Internet sockets specified in the /etc/inetd.conf file. When the inetd daemon receives a request on one of these sockets, it determines what service corresponds to that socket and then either handles the service request itself or invokes the appropriate server, such as ZSERV or PAWSERV.
A separate process exists for each concurrent connection to a given host.
As INETD is not available for VM/CMS, another solution has to be used. TCPAW uses the REXEC command to start servers on VM/CMS systems. The REXEC daemon autologs the machine of the specified user, having verified the username and password. This means that the machine in question must not be in use, i.e. logged on or disconnected. Once the machine is autologged, the ZSERV or PAWSERV program is started.
If you have problems connecting to a remote VM system, first check that the account is not in use. If you still have problems, ensure that your PROFILE EXEC does not contain any statements which cause it to run a command, e.g. EXEC MAIL, either unconditionally or in DISCONNECTED mode.