Wapp

procedure named "wapp-page-abcde" will be invoked to construct the reply.
If no such procedure exists, "wapp-default" is invoked instead.  The latter
technique is used for the hello-world example above.

The procedure generates a reply using one or more calls to the "wapp-subst"
command.  Each "wapp-subst" command appends new text to the reply, applying
various substitutions as it goes.  The only substitution in this example is
the \\n at the end of the line.

The "wapp-start" command starts up the application.

To run this application, copy the code above into a file named "main.tcl"
and then enter the following command:

>

     For debugging use only: open a listening TCP socket on _PORT_ and run
     an interactive TCL shell on connections to that port.  This allows for
     interactive debugging of a running instance of the Wapp server.  This
     command is a no-op for short-lived CGI programs, obviously.  Also, this
     command should only be used during debugging, as otherwise it introduces
     a severe security vulnerability into the application.

6.0 Limitations
---------------

Each Wapp process is single-threaded.
The fileevent command is used to allow accepting multiple simultaneous
HTTP requests.  However, as soon as a complete request is received, and
the "wapp-page-NAME" proc runs, all other processing is suspended until 
that proc completes.
Hence, a long-running "wapp-page-NAME" proc can cause the system to
become unresponsive.
If this is a problem, the Wapp application can be run in CGI mode.
In CGI mode, the overlying webserver will start a separate Wapp process
for each request, and there are no limits on the number of simultaneous
Wapp processes.

The POST data parser for Wapp currently only understands
application/x-www-form-urlencoded content.  Wapp does not (currently)
have a decoder for multipart/form-data content.  A multipart/form-data
decoder might be added in the future.  Or, individual applications can
implement their own multipart/form-data decoder using the raw POST data
held in the CONTENT entry of the ::wapp dict.


7.0 Design Rules
----------------

All global procs and variables used by Wapp begin with the four character
prefix "wapp".  Procs and variable intended for internal use begin with
the seven character prefix "wappInt".