handler(req)

This handler uses instances of subclasses of Servlet to handle HTTP GET and POST requests. These instances are referred to as servlets in this documentation.

1. A developer creates a class that subclasses Servlet or, more probably, HTMLPage, which already subclasses Servlet and has many features for generating HTML.

2. Let's say we have a class named Foo that subclasses HTMLPage. This class must be saved in a file called Foo.mps. (mps stands for Mod Python Servlet).

   Generally, for any servlet named SERVLET, it must be a subclass of Servlet and saved in a file named SERVLET.mps.
3. Apache needs to be configured to call this handler for Foo.mps. Assuming /var/www/html is your DocumentRoot and also assuming Foo.mps is saved in directory /var/www/html/mps_test then Apache needs the following configuration:

     <Directory /var/www/html/mps_test>
       SetHandler mod_python
       PythonHandler mod_python.servlet
       PythonDebug on
     </Directory>
   

4. When the server receives a request for /mps_test/Foo it will look for a file named Foo.mps in /var/www/html/mps_test, compile the file, look for a class named Foo, insure it is a subclass of Servlet, create an instance of this class, let's call it servlet, and then call, in order:
   1. servlet.auth()
   2. servlet.prep()
   3. servlet.respond()
   4. servlet.wrapup()
   See the documentation for the above methods of Servlet for details about each stage of processing the request.
5. Instances of a class are cached, so if a request for /mps_test/Foo comes in another request, the instance will be found in the cache and reused.

See the documentation for Servlet and HTMLPage for further details about servlet processing and helpful features.