NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/vmsnet/networks/tcpip/ucx/246

Internet Message Format | 1993-01-04 | 2.9 KB

Path: sparky!uunet!munnari.oz.au!bruce.cs.monash.edu.au!merlin!iwsd01.itwol.bhp.com.au!wewila
From: [e-mail] (Alan Wilkie)
Newsgroups: vmsnet.networks.tcp-ip.ucx
Subject: Multithreading and subprocesses in UCX
Message-ID: <[e-mail]>
Date: 5 Jan 93 08:14:51 +1000
References: <[e-mail]>
Organization: BHP Information Technology
Lines: 45

In article <[e-mail]>, [e-mail] writes:
> Using UCX2.0 under VMS5.5-2.
>
> When writing TCP/IP servers, is there an elegant method of having VMS sub/det
> processes handle multiple server connections, a'la U**x fork/exec.
>
> Is multi-threading the server (QIOs and ASTs) the only method?  In which case
> how are Telnet (etc.) connections, that create network processes under a
> different UIC, handled?
>
> Questions, questions, and so little documentation.  The usual apolgies (FAQ,
> etc.)  With thanks in advance.  Mark Daniel.

I may be overlooking something in your question here, but it should be fairly
easy to create a sub/det process to handle a connection.  UCX creates a device
socket to listen on the designated port, and when you actually want to accept
a connection, it creates another device socket for each connection (hence
allowing multithreaded servers because you can have a QIO outstanding on
each device with an AST to handle completion).

There are a couple of options then for handling a connection.  If you have
a standalone process listening for the incoming connection, you just accept
the connection and spawn/create another process passing the device UCX gives
you as the input/output channel for the process.  I think this is how the
REXEC/TELNET/etc type servers do it.

Alternatively, you can let UCX handle the connection initiation for you.
If you create a service (UCX command "CREATE SERVCE xxxxx") you can specify
a (.COM) file to execute to accept the connection.  When the service is
enabled, UCX starts listening to the specified port and starts a new process
for each incoming connection.  The process executes the .COM file to run the
appropriate server software.  There is also a logical called SYS$NET defined
which is set to the name of the device UCX has created for the connection,
so you then access/read/write/deaccess that device.  This is all fairly
similar to transparent DECnet.

Hope this has helped,
--
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Alan Wilkie, Analyst/Programmer, Process & Engineering Section    / / /\
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