• The web execution environment is event driven
• The web execution environment is usually running on phantom processes where you cannot see the output or use the debugger

What Debugging Services PicLan-IP Provides by Default

A Page Fails to Compile

If an active server page fails to compile, the capture from the mv/BASIC compiler (and the PicLan-IP pre-processor) will be output to the browser. You should be able to find the error based on the compiler error message in most cases.

A Page Takes Too Long to Execute

If an active server page takes too long to execute, the supervisor process will time it out and generate a simple error message to the browser. This error message will include the current state of processing within the PicLan-IP server which may include the name of the machine generated subroutine that is executing.  If you wish you can look at the source code for this subroutine in the WWW.CTRL,PGBASIC file.

The amount of time that the supervisor will wait before deciding that a process is hung is controlled by the SUPERVISOR TIME=hh:mm:ss in the config record.

What you Should Do To Make Application Debugging Easier

Debug on a Separate System

It is always easier to debug application no a web server that is not running live users.  While this may not always be practical, you should consider setting up your development environment in this manner if at all possible.

Shorten the PicLan-IP Web Server's Timeout Values

If you do not like to wait the 2 minutes for the supervisor process to timeout a hung process, change the timeout values to:

SUPERVISOR POLL=00:00:05
SUPERVISOR TIMEOUT=00:00:30

These settings assume that you system is fast enough to compile and run any active page in under 30 seconds.  If you system is not this fast (or your applications are this complicated), then you may need to use longer values.

Only Run a Single Web Server Process

It can get much less confusing if you only configure the PicLan-IP Web Server for a single helper process.

Clear the Web Server's Cache Poll

Some source code changes may not trigger the web server to re-compile your code.  For example, if you change only the contents of an INCLUDEd item, then the web server will not know that the mv/BASIC code needs to be recompiled.  You can tell the web server to recompile all mv/BASIC active content by typing the command:

CLEAR-CACHE

Setup Instrumented Compiles

If you specify the letter R in the HTTP DIR=... option settings, the PicLanIP Web Server will include instrumentation code in the generated code.  This allows the Web Server to produce much more detailed information to the browser if an application hangs including displaying the source code for the errant module and the last line that was to execute.

Using the R option during application development is highly recommended. You should remove the R option (and run a CLEAR-CACHE command) when you decide to deploy your live application.  The R option adds a considerable amount of code to your generated application code.  It's inclusion can easily make your application double in size and lower it's run-time performance by a factor of 20.

Use Source Level Debugging

You can debug many application logic issues by using the PL_PRINT ... statement to output messages to the PLIP-MONITOR console.  Be sure to take the statements out when you deploy the application in a production environment.

What to do if it Still Does Not Work

• Make sure that no PicLan-IP processes are currently running.  You may need to LOGOFF the processes and/or boot the host environment.
• At TCL in the PICLAN-IP account execute:

PLW-MAIN (E)

This will run a single web server process in the foreground.  You can press the letter 'X' to exit back to TCL.