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Starting and Stopping the Web Server

Starting and stopping the web server involves the following steps:

Normal Production Usage

The PicLan-IP software runs on a collections of MV processes. One of these processes is the "supervisor" process and one or more processes are "thread" processes. None of these processes are designed to accept terminal input from the user. These processes do output informational messages to the terminal (if one is connected) and also output these messages to a MV data item that can be monitored to "watch" PicLan-IP activity. It is important to remember that the activity that can be monitored only included messages that PicLan-IP outputs intentionally. If a process aborts, exits to TCL, or generates some other unanticipated system message, then you will not see that message on the monitored output.

For this reason, if you are experiencing any trouble configuration the PicLan-Ip software, you should run the PicLan-IP processes on "normal" MV ports that have terminals (or network connections) on which you can see the actual terminal output.

Run the command PLIP-START to log the web supervisor process on. The web supervisor process will in turn log the web thread processes on. The PLIP-START verb automatically runs the PLIP-MONITOR program that will watch the activity of the PicLan processes as they begin. If you wish to run PLIP-START without starting the monitor, include the (M option on the PLIP-START verb.

If you with to stop the web processing, run the command PLIP-STOP. This command will signal the web supervisor process to log off and to signal the web thread processes to log off. Stopping the web may take 20 seconds (or longer) depending on what settings are used and whether any web thread processes are busy at the time. When the web is stopped, all active requests are closed without any error messages. Users will get "connection reset by peer" in this case. The PLIP-STOP verb will also start the PLIP-MONITOR command, but will exit back to TCL when the last helper process finishes.

Do not log the web processes off manually with the Pick LOGOFF verb. To do so will leave TCP connections stranded requiring you to manually kill them.

Monitoring the Web Processes

The web processes (both supervisor and thread) generate information messages to the screen and also write these messages into buffer area. This buffer area allows you to "peek into" the running web server's processes using the PLIP-MONITOR command. PLIP-MONITOR is actually automatically started when you run PLIP-START unless you include the (M option to supress this behaviour. The PLIP-MONITOR command will display all of the supervisor and thread ports activity with the port number at the left followed by the message at the right. The PLIP-MONITOR program can catch up with at most 8K of outbound data without discarding some of the output stream. Also, you can only run one PLIP-MONITOR program at any time.

It is important to remember that PLIP-MONITOR will only display messages that are "normal" and "intended" from the supervisor and thread processes. If a process aborts, exits to TCL, or otherwise malfunctions in a manner not logable by the process itself, then PLIP-MONITOR will not display such output.

Changing Web Configurations While Running

It is perfectly acceptable to change the PLIP.CTRL CONFIG item while the web server is running. The web process threads check this file every six seconds and will automatically reconfigure whenever it is changed.

Also, if you change web configurations that need to invalidate Web Server cache settings, you should execute CACHE-CLEAR to clear the cache files so that new content is reflected. This is only necessary when your change in contents is caused by a change in the web server's configuration file and not because you changed the content itself.

Killing TCP Connection Control Blocks

If you have incorrectly stopped a web server thread process, then you may need to manually kill the TCP connection control blocks with the PicLan PL-KILL verb.  Non-native hosts have a stripped-down version of PL-KILL and PL-STAT included in the PICLAN-IP account.

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