5.2CGI stand-alone front-end

The WOPI CGI front-end, called falcgi is a stand-alone program (a binary executable for the target platform) which loads a Falcon script corresponding to its name.

The program is loaded by the web server, and data is passed to it through the common CGI application interface. As soon as the CGI program is ready, it searches for a falcon script bearing its same name (but having extension .fal, .ftd or .fam), loading and then executing it.

To write an application running under this front-end, it's necessary to configure your web server to run the CGI executable in response to the given request, renaming (or symbolic linking) the CGI program matching the name of the application.

Suppose there are two CGI applications that can be invoked under the /cgi-bin/ virtual location (it's content being found in the cgi/ directory), one to count the accesses performed on your site, and the other to perform some database query.

Then, you should copy the CGI WOPI application twice in your cgi/ directory, renaming it according to the task, or creating a symbolic link to perform a new task (and running a new script).

The directory structure of the above server may be:

   cgi/
      counter
      counter.fal
      query
      query.ftd
      query_element.fal
      utility/
         ...

Where counter and query are copies or symbolic link to falcgi executable, while counter.fal and query.ftd are the real CGI programs written in Falcon.

In considering what script to load, the falcgi program will discard its own extension, so that it can be used similarly also on systems requiring a certain file extension for execution. For example, the counter binary file in our example may be called also counter.exe, and it would still load and execute counter.fal.

Note: Be sure to read the Isomorphism of CGI based sites. documentation about specificities of the CGI model.

Configuration

The CGI front-end reads the following attributes from the main module:

• wopi_tempDir: Location where to store the temporary files. Defaults to /tmp on POSIX systems, and to C:TEMP on MS Windows systems.
• wopi_maxMemUpload: Maximum size for upload to be retained on memory instead being stored on disk.
• wopi_sessionTO: Session timeout (maximum live time for session cookies and data, in seconds).

Other than that, you have to activate the ability to execute CGI programs from within the web server you're currently using. Check the documentation of the web server for further information.